Deer damage to perennial shrubs, young trees, and ornamental annuals can cause a great deal of frustration and uncertainty among gardeners or home-owners. Our tolerance for these pests may be truly tested during the drier season, when they may all but take up residence in our irrigated gardens or landscapes. While numerous "deer-proofing" or deer repelling techniques are practiced in today’s landscaped settings, the most fundamental of all approaches is often ignored: the exploitation of plant species that have been repeatedly left unharmed within the infested area. The purpose of this project is to use the latter method to establish a deer tolerant plant setting within a deer infested coastal area, and to determine the results thereafter. Research will also be done, with the intent of compiling the following two lists: 1) Characteristics of unpalatable plants, and 2) Deer tolerant plant species.

I. Determination of experimental plant list

A. Observation within infested area

II. Establishment of project plant setting

	A. Locating a representative site
	B. Preparation of a suitable growing environment
	C. Plant installation

III. Observation 

A. Survey of deer population visiting site

	1. Frequency of visits
	2. Number of deer present

B. Recording any signs of deer browsing

	1. Within project plant setting
	2. Among surrounding flora

C. Noting deer preference to plant materials

  

IV. Research 

	A. Finding resources relating to deer problem
	B. List compiling

	1. Characteristics of unpalatable plants
	2. Deer tolerant plant species

a) Research in horticultural literature

b) Experimental trial

 

THIS REPORT CONTAINS RESEARCH DATA WHICH WAS COMPILED IN ORDER TO ESTABLISH A DEER TOLERANT PLANT SETTING. A BRIEF OVERVIEW OF OTHER DEER REPELLING TECHNIQUES IS ALSO INCLUDED, BUT DOES NOT FORM THE BASIS FOR THE REPORT IN ANY WAY. THE MAIN PURPOSE OF THE REPORT WAS TO ANALYZE THE CAUSES OF PLANT SUSCEPTIBILITY OR RESISTANCE TO DEER DAMAGE. THE PROJECT PLANT SETTING WAS INSTALLED WITHIN A DEER INFESTED COASTAL AREA IN THE FALL OF 1996. RESULTS WERE ASSESSED DURING THE FALL, AS WELL AS DURING WINTER AND SPRING OF 1997, AND INDICATED A DEFINITE DEGREE OF RESISTANCE AMONG THE EXPERIMENTAL PLANTS. PLANT MORPHOLOGY SEEMED TO BE PRIMARILY RESPONSIBLE FOR THE LACK OF INTEREST AMONG DEER IN THE AREA. THESE CHARACTERISTICS INCLUDED HAIRY LEAVES AND FLOWERS AS WELL AS ODIFEROUS FOLIAGE CONTAINING VOLATILE CHEMICALS. A LIST OF DEER TOLERANT PLANTS IS ALSO GIVEN AND THE MORPHOLOGICAL CHARACTERISTICS THAT PROBABLY MAKE THEM UNPALATABLE ARE INDICATED WHERE POSSIBLE. IN UTILIZING SUCH A LIST, ONE MUST REALIZE THAT WHAT DEER PASS UP ONE DAY MAY BE EATEN THE NEXT. YOUNGER PLANTS ARE MORE APT TO BE EATEN THAN OLDER ONES. DEER WILL ALSO MAKE THEIR PRESENCE KNOWN MORE DURING THE DRIER SEASON WHEN NATURAL DEER FORAGE BECOMES LIMITED. OBSERVING PLANTS THAT HAVE BEEN LEFT UNHARMED IN A SPECIFIC LOCALE AND CROSS REFERENCING THEM WITH DEER TOLERANT PLANT LISTS IS PROBABLY THE BEST WAY TO ESTABLISH A DEER TOLERANT SETTING IN A PROBLEM AREA.

The author would like to thank the Environmental Horticulture Science Department, California Polytechnic State University, San Luis Obispo, California, for donating all the plants used for the completion of this study.

MD

CHAPTER

	I..........................................................................	INTRODUCTION
	II.........................................................................	RESOURCE REVIEW
	III........................................................................	METHODS AND MATERIALS
	IV........................................................................	RESULTS
	V.........................................................................	DISCUSSION
	VI........................................................................	SUMMARY
	VII.......................................................................	RECOMMENDATIONS
		RESOURCES CITED
		BIBLIOGRAPHY

TABLE

1. Degree of deer damage to project plants during 40-day trial

 

LIST

 

	1. Characteristics of unpalatable plants
	2. Deer tolerant plant species

 

Figure

	1.	Deer damage to Juniper shrubs
	2.	Deer damage to Camellia
	3.	Deer crawling under fence
	4.	Deer damage to Xylosma
	5.	Deer inhabited coastal community
	6.	Site for project plant setting along deer path
	7.	Established project plant setting
	8.	Damage to project plants
	9.	Damage to surrounding plants during trial
	10.	Project plant setting in April, 1997
	11.	Deer in vicinity during trial
	12.	Plant morphology

Deer damage to perennial shrubs, young trees, and ornamental annuals can cause a great deal of frustration and uncertainty among gardeners and home-owners. A gardener’s tolerance for these pests may be truly tested during the drier season (summer to early fall), when they may all but take up residence in the irrigated garden or landscape.

The coastal region of San Luis Obispo County is home to an extensive deer population. Damage to ornamental annuals and perennials has been a common occurrence, especially within the suburban regions where landscaped gardens exist in close proximity to deer habitats (3).

There are several methods which utilize various techniques in controlling or eliminating deer damage to ornamental plants. The use of repellents to discourage deer from entering landscaped settings, or from further damaging susceptible plants, is often the resort of the gardener or grower. Excluding deer from the planted area is another method of control that usually depends on some sort of barrier which blocks the deers' possible entrance.

Fall of 1996 has proved to be a particularly bad season for deer damage in the San Luis Obispo area. At the author’s residence, located on the edge of Montana de Oro State Park in Los Osos, severe damage to well established perennials and annuals occurred, rendering areas of the landscape unattractive (fig.1 and 2). Some plants were left unharmed. Various deer repelling methods were used by the property owner with very little, if any, success.

While several "deer-proofing" or deer repelling techniques are practiced in today’s landscaped settings, the most fundamental, and conceivably the most effective of all approaches is often ignored: the exploitation of plant species that have repeatedly been left unharmed within the infested area.

The intent of this project is to use the latter method in establishing a deer tolerant plant setting, within a deer infested coastal area, and to analyze the results thereafter. The area that will be chosen for the study is the author’s residence, on the outskirts of Montana de Oro State Park in Los Osos. It is the author’s hope that an aesthetically pleasing plant setting can be established in spite of the fact that the region is inhabited by vast numbers of hungry deer. Key points of this project are the determination of an experimental plant list; the establishment of a project plant setting; and observations of deer populations, browsing, and plant preference. Research will also be done with the intent of compiling the following lists: 1) Characteristics of unpalatable plants, and 2) Deer tolerant plant species. In referring to the latter, it should be well understood that the list will be highly generalized since deer preference for plant material varies with region, as does the length of the dry season. For best results, the list should be cross-referenced with a list of plants observed to be ignored by deer or at least tolerant of minimal deer browsing. Interviews with nursery employees, horticulture professors, and home-owners, as well as research in related literature will act as resources for the study.

The California mule deer, Odocoileus hemionus californicus, is the most common species of deer that inhabit the coastal range of central California (12). For the purpose of this study, it should be made clear that these are the deer which one will encounter in the San Luis Obispo and coastal vicinity.

While some home-owners enjoy the sight of browsing deer, there are many that have quite the opposite view toward these potential garden pests. Damage caused by deer browsing on landscaped shrubs and trees becomes more common as plant settings are established in close proximity to deer habitation. As residential development occurs closer to deer territory, damage may appear throughout the year and appear less seasonal (5). In many of these situations deer are simply feeding in the same area as they were before the structures were built. The amount of damage may depend on a number of factors including weather conditions, availability of alternative foods, plant palatability, and seasonal factors (7).

California mule deer breed in December and January, and fawns are born in mid July (12). Natural deer browse is always limited during the fall season. This is due to the local climate and the absence of summer rain. Landscape plants are in a vulnerable position due to the sparse existence of natural deer forage. Young deer tend to be less cautious toward selecting a plant preference than older deer (8). This non-preference may further increase deer damage during the drier fall, as the young deer are led out by their parents in search of food.

The most reliable way to protect a garden against deer damage is exclusion-- constructing a fence or enclosing selected plants in wire cages (11). A fence that is built for this purpose must be high enough to prevent deer from leaping over, and solid enough to prevent crawling underneath-- for deer are great jumpers and crawlers (fig. 3). In most situations these latter methods will detract from the beauty of the landscape. Although this may be the case, operations such as nurseries, orchards, and large scale gardens may have no other alternative as a means of preventing deer damage.

The use of commercial deer repellents is often considered as a way to deter deer from entering a garden area or from sampling plant material (9). Some repellents emit a discouraging scent which drives the deer away while others act on the deer’s taste buds and digestive system. Repellents must be applied frequently and are best used for short term applications while recent plantings are becoming established. Unfortunately the first rain or water applied during irrigation usually nullifies their effectiveness (12). These remedies provide only temporary relief and require a good deal of vigilance on the gardener’s part. They also may detract from a garden’s natural image or the otherwise pleasant smell of plants and flowers. In a study on the relative effectiveness of repellents for reducing mule deer damage written up in the Journal of Wildlife Management, the authors conclude:

"The relative effectiveness of repellents for deterring deer feeding depends on

the hunger level of deer, the relative palatability of the species to be protected,

and the concentration of repellent on the treated vegetation. If deer are

moderately hungry, repellents probably will not deter browsing" (1; p-341).

Most deer repelling methods remain debatable because the control measures may be largely ineffective and questionable during the drier periods of the year in highly populated deer territory.

Probably the most fundamental approach at reducing or eliminating deer damage is to grow what deer won’t eat. Although there are several published lists of plants thought to be deer resistant, one must realize that depending on the time of year and the individual taste preferences of the deer in the area, deer may eat plants thought to be resistant (11). What deer pass up one year may prove to be irresistible the next year (13). Young plants are often preferred over mature ones. Recently established plants are subject to a deer’s curiosity. Also, what is overlooked in the spring may be eaten in the fall, when natural forage becomes limited (fig. 4). "Certain plants may not suffer deer damage in some gardens and landscapes, yet might be completely destroyed in others" (11; p-3).

Avoidance of deer damage through the use of tolerant plants offers the gardener or home-owner a long-term solution to the pest problem. There is no hassle in applying sprays or other repellents. Excluding the deer from the property with artificial barriers is not required since deer will find the plants to be unpalatable. Only plants known to be ignored by the local deer population should be used and this will require careful observation, specifically within and around the landscaped area (11). Some plants (for example, members of the rose family) are known to be particularly appealing to deer (6). These and others should not be considered where deer are a problem.

Using native plants as a means to reduce deer damage should not automatically be considered as a deterrent to deer browsing. Opinions vary on its true effectiveness. Some say that natives should be considered first in landscape planting (5). Others believe that natives may be more likely to get eaten in deer country than their exotic counterparts (6). In most areas, natural deer forage occurs most abundantly as native vegetation so it would seem pointless to plant these natives in a landscaped garden. Natives, however, are best adapted to the local climate and might stand up the best to deer browsing. This is probably the reason that most of the native flora flourishes within deer habitats. Deer also evolve along with the native flora and become accustomed to the local plant palette. For example, ceanothus is often said to be ignored by deer in some areas; but, in other areas deer actually may prefer this genus over others (6).

Several factors may be responsible for a deer’s non-preference for individual plant species. A good understanding of these factors will aid in the determination of a deer resistant plant list. Characteristics that tend to impart resistance to plant species include tomentose (hairy) leaves, sticky leaves or stems, and sharply serrated leaf margins (9). Besides these morphological characteristics, plant chemistry may be responsible for a deer’s non-preference. Certain plants produce toxins which make them unappealing to deer (3). In a study on the influence of sagebrush terpenoids on mule deer preference published in the Journal of Chemical Ecology, the authors summarized: 

"Our choice tests provide further evidence that a variety of allelochemicals,

located on the epidermal surface of sagebrush foliage, could be affecting

deer selection" (2; p-2062). 

Allelochemicals include defensive chemicals, which may produce negative responses in deer and act as feeding deterrents (10). Many highly aromatic plants also possess a natural safeguard against browsing damage. These volatile chemicals are directly responsible for a deer’s non-preference. "The more volatile oils a plant contains, the less it is favored by deer" (12).

Deer preference for individual plant species can be easily examined, especially during the fall when their intrusion into the landscape is most likely. In a study which was aimed at assessing the forage preferences of white tailed deer, the author wrote: 

"The deer were always selective when feeding. They sniffed about and ate

individual leaves or twigs. Deer appeared to detect differences among

individual leaves on the same plant by sniffing, licking or holding the leaves

in their mouths before accepting or rejecting them" (4; p-85).

Avoiding deer damage through the use of deer resistant plants is very economical and requires little labor and upkeep. Barriers may be costly, require much more labor for installation, and may be an eyesore around the garden. If a gate or entrance is accidentally left open, even for just one night, deer damage may occur extensively. Cages placed directly around the plants may be subject to misadjustment due to wind, rain, or foot traffic. Repellents require repeat applications and this may prove troublesome to a gardener or grower. Environmental factors such as sun, wind, or rain may also render certain repellents ineffective. Their foul smell may offend guests or visitors to the garden. The sight of some repellents, such as soap bars or human hair, may detract from the beauty of the garden.

In selecting a deer resistant plant list, one may observe the plants which have repeatedly been left unharmed within the landscape and cross-reference these with published deer tolerant plant lists. It is the intent of this study to establish a deer tolerant plant setting using the latter method and to determine the causes of plant susceptibility or resistance. The plants selected must be tolerant of coastal conditions such as wind, fog, and sandy soil since it is within this environment that the experiment will take place.

Determining an experimental plant list was necessary in order to establish the project plant setting. This included careful observation within the deer infested area. Specimen plants found to be repeatedly left unharmed were used for the experimental trial. The plants chosen were Mexican sage (Salvia leucantha), French lavender (Lavandula dentata), and Rosemary (Rosmarinus officinalis). Two specimen Rosemary plants, one French lavender shrub, and one Mexican sage bush were present on the property. All seemed to show resistance to deer browsing for one reason or another. All four of these well established perennials were located just off a known deer browsing route and were growing close against the existing structure.

Because the experiment was being carried out during the late fall, the project plants and the surrounding flora were most susceptible to deer browsing. Therefore, any plants that remained unharmed during the experiment could be judged as having a definite high degree of resistance within the area or specific locale.

In order to evaluate any damage which might occur, the project plants needed to be established in a favorable growing environment. This would maximize their growth potential, and make it possible to more efficiently rate or categorize the effects of any deer browsing. Heavy nitrogen fertilization will be avoided, since deer tend to prefer the resulting flushes of tender, new growth (12). It was also essential for the plants to be tolerant to coastal conditions including fog, salt air, and wind. The three species met this requirement.

On November 21, 1996 the faculty of the Environmental Horticulture Science Department at Cal Poly San Luis Obispo donated twenty-one plants to be used in the experiment. Seven of each species were selected, all in one gallon containers. The plants were all in good condition and well adjusted to the local environment. They were taken to the author’s house in Los Osos where they would be established in the project plant setting.

Locating a representative site for the project was essential in order to obtain results representative of the local deer population and plant susceptibility and resistance. The site chosen was on the west facing side of the author’s residence which borders vast acreage of a coastal scrub and sand dune community (fig. 5). The area is inhabited by an extensive mule deer population. The site was located directly on a known deer path which would put the experimental plants in a vulnerable position ( fig. 6).

On November 23, a suitable growing environment was prepared for the setting. This involved adding a small amount of top soil amendment to the sandy soil which is representative of the coastal area. This improved the water holding capacity and fertility characteristics of the growing medium. The plants were installed at 3 to 5 foot spacings and two tablespoons of Osmocote fertilizer were added to each hole. A layer of shredded cedar bark was placed on the soil surface around each trunk in order to reduce evaporation from the soil surface (fig. 7).

Observation will include surveying the deer population visiting the site. The frequency of visits will be considered as well as the number of deer present. Since deer damage has almost exclusively occurred during the nighttime hours it will be necessary to rake the sand nightly in order to confirm that deer are visiting the site. Their hooves leave a tell-tale sign of their nocturnal presence. Watering the raked sand will not be necessary due to the inflow of moisture off the coast during the night. Dew that condenses on the soil surface permits detailed footprints of deer that have browsed in the vicinity or passed by over night. Observations will be made each morning for the first week of the experiment and every fourth day thereafter for a period of 40 days. At this point winter rains will probably nullify the results of the trial since natural deer forage will be replenished. Any spring browsing that occurs will be considered as well, and the effects will be discussed. Signs of deer browsing within the project plant setting and among the surrounding flora will be noted. The project plants will be assigned numbers and damage will be assessed as minor (less than 10% of the total shoots being eaten or damaged), moderate ( 10-40%), and major ( 40% or more). The percentage of the shoot eaten will also be considered in assessing any damage. Ragged edges on the ends of torn twigs is another tell-tale sign of deer browsing. This is due to the deer lacking upper front teeth, requiring them to tear the twigs instead of snipping them off (12). Deer preference as to plant material will be observed throughout the project.

Table 1 contains the results of our experiment throughout the 40-day trial period. All plants showed some degree of resistance to major deer damage. The Rosemary remained completely ignored by the local deer population. Minor or moderate damage was observed on the French lavender and Mexican sage. One sage and two lavender plants were subject to minor deer browsing on the very first night. The only other damage occurring on the sage took place on the fourth night and was listed as moderate. Two incidences of deer browsing were evident on the lavender in early December and three previously unharmed shrubs received moderate damage from deer browsing in late December. In all cases the deer seemed to prefer only the tender, youngest shoots or the flower stalks (fig. 8).

The determination that deer were responsible for all damage that occurred was based on the facts that 1) deer prints were strongly evident around the perimeter, 2) shoots were torn rather than snipped, and 3) deer were observed in the project plant area during day and nighttime hours.

Spring browsing was also evident in early April. This occurred only on the French lavender shrubs and was minor in nature. Minor to moderate deer damage also occurred on other landscape plants around the structure including Agapanthus orientalis, Echevaria ibricata, Strawberry, Gazanias, Papaver spp., Heavenly bamboo, and Dicksonia antarctica. This occurred in early spring (fig. 9).

All project plants were able to continue thriving in spite of the amount of browsing that occurred and had become well established by early spring (fig. 10). Deer were also observed browsing throughout the adjacent native flora during the weeks of the trial and the months following (fig. 11). 

It is evident from the results of the experiment that certain plants display a definite degree of resistance to deer browsing and the amount of damage that may occur will vary from plant to plant. Any interest in the project plant setting by the local deer population seemed to be only temporary, as if curiosity was the driving force behind the feeding and taste, plant chemistry, or texture caused the deer to stop eating after only minor or moderate browsing.

There are several factors, the effects of which may have combined to impart resistance to the project plants. Plant morphology was probably the primary reason for the lack of interest. Upon examination of leaf morphology it was noted that the Mexican sage foliage had a characteristic tomentose (hairy) underside. This pubescence was also observed on the French lavender shrubs. The flowers on each of these species also appeared to be quite furry (fig. 12). Deer tend to be most attracted to flowers with soft, turgid petals that have a more fleshy structure. The Rosemary plants were found to be very odiferous and the leaves contained generous amounts of the volatile oils responsible for the emanation. It was most probable that the deers’ olfactory senses caused the observed non-preference in this instance. The lavender and sage also had a fairly volatile aroma. The following list contains several characteristics of unpalatable plants that may impart resistance to deer browsing.

LIST 1. Characteristics of unpalatable plants for deer browsing.

-hairy leaves, flowers, or stems (tomentose, pubescent, furry, etc.)

-sticky leaves, flowers, or stems

-spiny leaves, flowers, or stems

-heavily serrated leaf margins or tips

-tough, leathery foliage

-stems or leaves containing latex sap

-odiferous plant parts containing volatile oils

-plants grown steadily, or slowly, without high nitrogen fertilization

-plants poisonous to deer

-native plants adapted to deer browsing

-extremely woody plants

Another general factor which may have protected the plant setting against excessive deer browsing was the repetition of plant material. Less variability in a plant palette may be responsible for less snooping. The more species one tries to include in the landscape, the more chance there is of a deer finding an adequate dinner. Once a list of deer tolerant plants has been determined, they should be considered first in the landscape, especially around the outside perimeter where deer will first visit. The project plants chosen for this experiment were determined by observing plants already present on the property and which seemed to be ignored by deer. However, only one or two of each species existed, and were located close against the structure acting as foundation plantings. Because of this, the plants were not automatically assumed to be deer tolerant. Deer are less apt to venture in close to an existing structure since this increases their chance of encountering humans or other predators.

It was made sure that the project plants were properly maintained, as this would allow the best chance of survival in the event of leaf loss to deer browsing. It is important for plants to be grown under optimum conditions in deer territory for this reason. This experiment was carried out during the late fall, when deer browsing was at its highest peak. This was done in order to determine if the project plants had a high degree of resistance. In theory, the best time to plant a prospective deer tolerant landscape would be winter or early spring, just after the first heavy rain. This would allow the plants to establish a mature root system and adequate shoot growth while the local deer population was busy foraging in the rejuvenated native landscape.

The project plant setting was undoubtedly visited by the same deer on repeat occasions. Once a deer’s curiosity has been satisfied during initial visits to a newly installed site, browsing will be less likely to occur during later visits in the event that the plants are found to be unpalatable. This probably played a part in the lack of interest in the project plants, especially since deer were observed on numerous occasions browsing only several feet away on the native vegetation.

Rainfall during the winter also may have affected deer browsing temporarily. However, less than average amounts fell locally so the effect on deer browsing was not pronounced. Deer were also seen browsing in the direct vicinity of the project plant setting throughout the winter months while the project plants themselves were generally ignored.

Damage to landscape plants can be a major problem in areas frequented by browsing deer. While constructing a deer-proof fence is the most reliable method of deer control, it may be costly. It also may distract from the surrounding landscape's beauty or "openness". Deer repelling methods remain debatable because the control measures may be largely ineffective and questionable during the drier periods of the year. Growing plants that deer won’t eat is the most economical alternative to eliminating or reducing deer damage.

The experiment was carried out in order to determine if a deer tolerant plant setting could be established using specimen plants observed to be ignored by the local deer population. The plants were installed on a known deer browsing route during the fall dry period. This was done in order to determine the realistic tolerance levels of the plants in the event of any browsing that occurred. The project was not a test to determine if the plants were "deer-proof" since deer are apt to try just about anything, especially during the driest period of the year. Observations of deer presence, browsing, and plant preference were made during the months of the experiment. It was further determined what the causes were for plant susceptibility or resistance.

All the project plants remained in good health in spite of the browsing that did occur. The characteristics that seemed to impart resistance to the plants were generally morphological in nature. These included tomentose leaves, flowers, and stems. The three species used for the trial were all strongly odiferous as well. Deer that visited the site characteristically stopped feeding after only minor to moderate damage. In fact, deer seemed to prefer other landscape plants in the vicinity over the plants chosen for the project plant setting.

The following list contains plants that should be considered in areas that are frequented by browsing deer. The list has been condensed from three separate sources which were all used as resources for this study. These include a Fish and Game guide to preventing deer damage, a deer tolerant plant list published by Graeber Gardens of Salinas, California, and the Sunset Western Garden Book. It should be noted that some of the plants that will be resistant in some areas may be eaten in others. Some may be nibbled on, yet not destroyed. Young plants may also be eaten while older ones remain ignored. The author has personally observed some of the indicated species to be eaten by deer in the area which again confirms the generalities present in such a list. Before considering any of these plants for use in deer territory, one should observe the landscape around them to see if any of the published plants are doing well at their locale. Only plants common to at least 2 of the 3 lists were included in the condensed listing. 

* Only plants common to at least two of the three sources were used in the condensed listing. Some plants that will be resistant in certain areas may be eaten in others. Some may be nibbled on, yet not destroyed. Young plants are also preferred over mature ones of the same species. What deer pass up one day, may be eaten the next.

** Indicates species which the author has personally observed to be nibbled on by deer, but not necessarily destroyed.

Abies spp.	Fir (pointed needles)	some native
Acacia spp.	Wattle
Acer palmatum	Japanese maple
Acer negundo	Box elder	native
Albizia distachya	Plume albizia
Albizia julibrissin	Silk tree
Arbutus menziesii	Madrone	native
Arbutus unedo	Strawberry tree
Cedrus spp.	Cedar (pointed needles)	some native
Ceratonia siliqua	Carob
Cercis occidentalis	Western redbud	native
Chamaecyparis spp.	False cypress	native
Cordyline australis	Dracaena palm (tough leaves)
Craraegus spp.	Hawthorn (thorny branches)	some native
Cupressus spp.	Cypress (volatile aroma)	some native
Eucalyptus spp.	Eucalyptus, Gum (volatile aroma)
Fraxinus velutina	Arizona ash	native
Ginko biloba	Ginko (leathery leaves)
Hakea suaveolens	Sweet hakea (sharp foliage)
Ilex spp.	Holly (sharply serrate margins)
Juniperus spp.	Juniper** (volatile aroma)
Liquidambar styraciflua	American sweet gum
Lithocarpus densiflorus	Tanbark oak (serrate margins)	native
Lyonothamnus floribundus	Catalina ironwood	native
Magnolia spp.	Magnolia (tough, leathery leaves)
Maytenus boaria	Mayten tree
Melaleuca leucadendra	Cajeput tree (tomentose leaves)
Metrosideros excelsus	New Zealand Christmas tree (woolly leaves)
Palms	(all) (tough, pointed, or thorny leaves)
Parkinsonia aculeata	Mexico palo verde (spiny twigs)
Picea spp.	Spruce (prickly needles)	some native
Pinus spp.	Pine (needles)	many native
Platanus racemosa	Califonia sycamore (tomentose)	native
Podocarpus spp.	Yew Pine
Robinia psuedoacacia	Black locust (thorny branchlets)
Schinus molle	California pepper tree
Umbellularia californica	California bay laurel (odiferous)	native

Arctostaphylos spp.	Manzanita (woody)	many native
Baccharis pilularis	Coyote bush	native
Berberis aquifolium	Barberry (spiny leaves)	some native
Brugmansia spp.	Angel's trumpet
Buddleia davidii	Butterfly bush
Buxus spp.	Boxwood (woody)
Callistemon spp.	Bottlebrush (bristly flowers)
Calycanthus occidentalis	Spice bush (strongly odiferous)	native
Carpenteria californica	Bush anemone (thick leaves)	native
Ceanothus gloriosus	Wild lilac	native
Choisya ternata	Mexican orange
Cistus spp.	Rockrose
Coleonema pulchrum	Pink breath of heaven**
Coprosma repens	Mirror plant (thick leaves)
Corokia cotoneaster	Corokia contoneaster
Correa spp.	Australian fuchsia (felted leaves)
Daphne spp.	Daphne (odiferous)
Dodonea viscosa	Purple hopseed bush
Echium fastuosum	Pride of Madeira (velvety leaves)
Elaeagnus pungens	Silverberry (spiny branchlets)
Erica spp.	Heath (needle-like leaves)
Euonymus japonica	Evergreen euonymus (leathery leaves)
Forsythia spp.	Forsythia
Grevillea spp.	Grevillea (sharp, pointed foliage)
Griselinia lucida	Griselinia (thick, leathery leaves)
Heteromelles arbutifolia	Toyon (tough, serrated leaves)	native
Jasminum spp.	Jasmine**
Lantana montevidensis	Trailing lantana (leaf hairs, odiferous)
Lavandula spp.	Lavender** (tomentose, odiferous)
Leptospermum spp.	Tea tree (woody)
Myrica californica	Pacific wax myrtle	native
Nandina domestica	Heavenly bamboo**
Nerium oleander	Oleander (poinonous)
Plumbago auriculata	Cape plumbago
Potentilla fruticosa	Shrubby cinquefoil
Rhododendron macrophyllum	Coast rhododendron (leathery leaves)
Rhus ovata	Sugar bush (leathery leaves)	native
Ribes spp.	Current (odiferous, spiny)	native
Rosmarinus officinalis	Rosemary (strongly odiferous)
Salvia spp.	Sage** (odiferous, tomentose)
Santolina chamaecyparissus	Lavender cotton (tomentose)
Syringa vulgaris	Common lilac (odiferous)
Syzyrigium paniculatum	Australian bush cherry
Teucrium paniculatum	Germander
Yucca spp.	Yucca (pointed or serrate foliage)	some native

Ajuga spp.	Carpet bugle (hairy stems)
Asparagus spp.	Asparagus (spiny stems)
Fragaria chiloensis	Sand strawberry (tomentose)	native
Gelsemium sempervirens	Carolina jessamine
Hedera helix	English ivy
Hibbertia scandens	Guinea gold vine
Hypericum spp.	St. John's wort
Osteospermum fruticosum	Trailing African daisy
Solly heterophylla	Australian bluubell creeper
Tecomaria capensis	Cape honeysuckle
Vinca spp.	Periwinkle

Ageratum houstonianum	Floss flower (hairy leaves)
Campanula medium	Canterbury bell
Catharanthus roseus	Madagascar periwinkle
Clarkia amoena	Godetia	native
Impatiens balsamina	Balsam (sharp, toothed leaves)
Moluccella laevis	Bells of Ireland
Myosotis sylvatica	Forget-me-not
Papaver spp.	Poppy**
Zinnia spp.	Zinnia

Further research could be conducted as a means to identify the naturally occurring plant defensive chemicals (allelochemicals) that make certain plants unappealing to deer. Extracts from plants that contain these chemicals could be used to spray susceptible landscape plants, and the resulting deer preference could be noted. These extracts probably would not have a foul smell that would detract from a garden. Research could also be done by testing greater numbers of landscape plants, in more of a trial and error process. These experiments should be carried out during the driest time of the year in order to gain realistic results that are indicative of the local deer population.

Determining the susceptibility of a native plant setting to deer damage is another experiment that one could pursue and one of which little research has yet to be conducted.

Planting specific "host-plants" for deer to feed on may be another way to avoid damage to ornamentals in the landscape provided ample space exists. Research could be done to determine common forage grasses or weeds that deer will prefer or simply feed on before venturing too far into a garden.

As human expansion occurs deeper into suburban deer habitats, there will be an increased need to avoid damage to landscape plants. Further studies of deer tolerant plants species and deer repelling methods will be necessary in order to establish healthy, attractive landscapes within deer territory. Deer are a pleasant sight to have within a garden or around its perimeter. By establishing methods that provide protection to landscaped gardens and identifying characteristics that impart resistance to individual species, it may be possible to have deer around and still enjoy their presence. 

1. Andelt, W. F., K. P. Burnham, and J. A. Manning. 1991. Relative Effectiveness of Repellents for Reducing Mule Deer Damage. The Journal of Wildlife Management. 55: 341.

2. Bray, R. O., C. L. Wambolt, and R. G. Kelsey. 1991. Influence of Sagebrush Terpenoids on Mule Deer Preference. Journal of Chemical Ecology. 17: 2053-2062.

3. Brian Lee. November 10, 1996. Personal interview. Los Osos Valley Nursery, 301 Los Osos Valley Road, Los Osos, CA 93402.

4. Chaplin, Raymond E. Deer. Blandford press. Poole, Dorset. 1977.

5. Coey, B. and K. Mayer. 1984. A Gardener’s Guide to Preventing Deer Damage. California Department of Fish and Game. P. 1-13.

6. Dave Fross. January 9, 1997. Interview. Environmental Horticulture Science Department, California Polytechnic State University, San Luis Obispo, CA 93407.

7. Jauron, Richard. (1993). Resistance of Trees and Shrubs to Deer Damage. Horticulture and Home Pest Newsletter [Online]. Available:http://www.ipm.iastate. edu/ipm/hortnews/

8. Marge Neiswanger, November 11, 1996. Phone communication. 2570 Pecho, Los Osos, CA 93402.

9. Miller, Lois M. 1984. Deer Control In Ornamental Gardens. Senior project, California Polytechnic State University.

10. Pedigo, Larry P. Entomology and Pest Management. Macmillan Publishing Company. New York, NY. 1989.

11. Rogers, Phila W. 1996. Smart Planting Keeps Deer Out of the Garden. OutdoorCalifornia. 17: 18-20.

12. Rue, Leonard L. The Deer of North America. Crown Publishers, Inc. New York, NY. 1978.

13. Sunset Western Garden Book. 1995. Editorial Board. 624 pp. Sunset Publishing Corporation., Menlo Park, CA.

1. Andelt, W. F., K. P. Burnham, and J. A. Manning. 1991. Relative Effectiveness of Repellents for Reducing Mule Deer Damage. The Journal of Wildlife Management. 55: 341.

2. Bigart, Charles. 1994. Garden To Garden. Organic Gardening. 41: 74.

3. Bob Hill, November 11, 1996. Personal interview. 2570 Pecho, Los Osos, Ca 93402.

4. Bray, R. O., C. L. Wambolt, and R. G. Kelsey. 1991. Influence of Sagebrush Terpenoids on Mule Deer Preference. Journal of Chemical Ecology. 17: 2053-2062.

5. Brian Lee. November 10, 1996. Personal interview. Los Osos Valley Nursery, 301 Los Osos Valley Road, Los Osos, CA 93402.

6. Chaplin, Raymond E. Deer. Blandford press. Poole, Dorset. 1977.

7. Coey, B. and K. Mayer. 1984. A Gardener’s Guide to Preventing Deer Damage. California Department of Fish and Game. P. 1-13.

8. Dave Fross. January 9, 1997. Personal interview. Environmental Horticulture Science Department, California Polytechnic State University, San Luis Obispo, CA 93407.

9. Graeber Gardens. 1993. Deer Proof Plants, Or Close to It. Graeber Gardens, 115 Salinas Monterey Hwy, Salinas, CA 93908.

10. Hume, William L. 1987. The Efficacy of Olfactory and Gustatory Repellents in Protecting Grapevines From Deer Depredation. Senior project, California Polytechnic State University.

11. Jauron, Richard. (1993). Resistance of Trees and Shrubs to Deer Damage. Horticulture and Home Pest Newsletter [Online]. Available:http://www.ipm.iastate.edu/ipm/hortnews/

12. Marge Neiswanger, November 11, 1996. Phone communication. 2570 Pecho, Los Osos, CA 93402. 

13. Miller, Lois M. 1984. Deer Control In Ornamental Gardens. Senior project, California Polytechnic State University.

14. Pam Haworth. November 11, 1996. Personal interview. 85 Costa Azul, Los Osos, CA 93402.

15. Pedigo, Larry P. Entomology and Pest Management. Macmillan Publishing Company. New York, NY. 1989.

16. Rogers, Phila W. 1996. Smart Planting Keeps Deer Out of the Garden. OutdoorCalifornia. 17: 18-20.

17. Rue, Leonard L. The Deer of North America. Crown Publishers, Inc. New York, NY. 1978.

18. Sunset Western Garden Book. 1995. Editorial Board. 624 pp. Sunset Publishing Corporation., Menlo Park, CA.