Gardening with Deer at Scott Point,
Salt Spring Island
by Arlene Ommundsen
(This is an abridged version of a four-part article published in the Grapevine magazine in 2010.)
We live at Scott Point, Salt Spring Island, British Columbia, where deer density is roughly 10 times historical levels. There are few natural predators remaining and deer have been attracted to neighborhoods where easy sources of food are available. The deer have become encultured to eating non-native plants and may cause considerable damage in gardens. Nevertheless I have found it possible to have an unfenced garden with the judicious use of certain plant material and a willingness to protect small plants until they are big enough to survive “tasting” by the deer.
Deer eat the new growth of trees, shrubs, grasses, ferns, and forbs, and often trample on small delicate plants. Male deer rub their antlers on small trees in the fall to remove the antler velvet. Such trees can die if the bark is heavily damaged. Bucks also practice sparring with their antlers against trees and shrubs, breaking branches.
There appears to be a hierarchy of plants ranked according to preference such that a deer will take the best that is available at any particular time of the year. (However, fawns are very adventurous and will try almost anything.) My neighbour has a beautiful bank of Vinca that the deer ignore until December, when they strip off all the leaves. Fortunately the plants survive and bloom profusely in the spring.
Deer diets may vary from one region of the island to another, as growing conditions and types of native vegetation vary. Walking around your neighbourhood will give you an idea of what is safe to plant outside the fence. Deer may eat almost any species including small amounts of toxic plants. Toxicity varies among individual plants depending upon the amount of sunlight that they receive. Also, flowers may be less toxic than leaves or roots of a plant. Deer in our area regularly eat the daffodil flowers blooming in the early spring when there is little else available, but ignore late-blooming daffodils.
Deer are creatures of habit, regularly following paths through their range. Plants on or near these paths will be more heavily browsed. I have planted the boulevard and the deer keep it well weeded for me!
I have found three categories of plants that coexist with the deer. These are (1) well-known poisonous plants, (2) plants of low deer preference, and (3) browse-tolerant plants. I will discuss examples of plants in each of these categories.
(1 ) Plants toxic to deer
One of the most successful ways of gardening in areas of high deer density is to use well-known plants that are poisonous to them.
Colchicum, often called autumn crocus or naked lady, is protected by the highly toxic chemical colchicine. This plant produces leaves in the spring, which die down in the heat of the summer, leaving the flower to shine on their own in the fall.
The genus Daphne includes a number of lovely plants known especially for their beautiful fragrance. They are protected by mezerein, an acrid resin. Daphne mezereum, though not evergreen, is prized for it’s early spring flowers before the leaves appear. Daphne odora 'aureomarginata' and Daphne x burkwoodii 'Carol Mackie' are both evergreen and variegated. Daphne laureola is considered a noxious weed in certain areas.
Members of the comfrey family, Boraginaceae, contain varying amounts of protective alkaloids. These plants include the common forget-me-not, Myosotis sylvatica. The large-flowered comfrey Symphytum grandiflora makes a lovely ground cover under the trees and is very drought-tolerant. Creeping comfrey, another Symphytum species, does very well in sunny areas and is also drought-tolerant. Trachystemon orientalis has large leaves like a hosta but may drop them in a cold winter, sending up its blue flower spikes before the new leaves appear. Most of these plants are less than 12 inches high and have blue or blue and white flowers.
Probably all of us have had the common foxglove, Digitalis purpurea, make an appearance in our gardens or have encountered it at the edge of the forest. Some of the other Digitalis species do not appear to be as toxic and may be eaten by deer.
Two spectacular plants that require a little more care, or can be treated as annuals, make a lovely focal point in the garden. They both contain alkaloid poisons and must be treated with respect. Ricinus communis, the castor bean plant, grows very fast. Shrub-like, this annual herb with red-purplish stems and large leaves contains most of the poison in its seeds. Angel’s trumpet or Brugmansia x candida is a long-lived, woody tree or shrub, with large, fragrant, pendulous flowers. It is generally not hardy in our climate and must be protected for the winter, but that is well worth the trouble.
The euphorbias, which include the poinsettia, have a latex-like sap. The various species contain differing amounts of many di- or tri-terpen esters, which are caustic to the skin and mucous membranes. I have found euphorbias to be avoided by the deer with the exception of poinsettias and Euphorbia robbiae. Robb's euphorbia is very invasive as well so I wouldn’t recommend it. One of my favourites is Euphorbia characias ssp wulfeneii. It will grow in full sun but will take partial shade and is very drought-tolerant and evergreen. When pruning these plants it is a good idea to wear eye protection, and keep in mind that certain poisonous plants are not appropriate if small children frequent your garden.
(2) Plants of low deer preference
Plants of low deer preference may be avoided by deer because they are low in nutrients, contain some toxins, or have an unpleasant smell or taste.
A number of plants that the deer don’t much care for are grey in colour, such as Santolina chamaecyparissus (lavender cotton), Stachys lanata (lambs ears), Helichrysum italicum (curry plant), Senecio cineraria (dusty miller), and Lychnis coronaria (rose campion), although the deer do eat the Lychnis flowers. Grey colour is no guarantee of protection though, as my young Artemesia plants are eaten.
Many grey plants are also very drought-tolerant and prefer full sun. Two of my favourites are Phlomis halica (pink phlomis) and Phlomis fruiticosa (Jerusalem sage). They may be borderline hardy in higher elevation areas. Phlomis russeliana, with its green leaves, is hardier but susceptible to grazing.
Rosmarinus officinalis, both the upright and trailing rosemary, are ignored by the deer in my sunny garden, but I haven’t been as fortunate with lavender. The deer eat the new growth on my English lavender so I don’t get flowers until late in the summer. Lavendula stoechas (French lavender) has been ignored thus far.
Perovskia atriplicifolia (Russian sage) is another sun-lover that is ignored by deer if not cut down to the ground in the fall. Sprays of flowers can be removed at the end of the season.
Perennial Verbascum chaixii (nettle-leafed mullein) is also deer-resistant and is available in different colours. It is one of the few truly perennial mulleins and does well in poor soil though it needs some water.
Gravillea banksii from New Zealand has very fine needle-like leaves and red flowers. It will take full sun but is tolerant of partial shade and very drought resistant. It requires protection while small.
Buxus sempervirens ‘Suffruticosa’ (English boxwood) is ignored by the deer in our area but unfortunately they eat the variegated form.
No garden would be complete without some winter flowering hellebores. They do give off a mild sulphurous odour that may discourage deer but is hardly noticeable to us. They prefer some shade but can tolerate a fair amount of sun if given sufficient water, and their flowers are long lasting. Helleborus corsicus grows to two to three feet with tough leaves and large blooms. Helleborus orintalis is only 24 inches high but it’s flowers come in many colours as well as doubles.
Iris foetidissima, with its bright orange seed pods, is the only iris that I can grow outside the fence. The deer eat my Pacific coast iris flowers, but a neighbour with dogs is more successful at keeping blooms. Another safe plant with an iris-like shape is Libertia grandiflora. It likes full sun and has white blooms. The bulb Leucojum aestivum (summer snowflake) also has white flowers and blooms in late spring.
Chrysanthemum maximun (Shasta daisy) is generally ignored year round. Scented geraniums are another safe plant but not reliably hardy every year on Salt Spring.
Another option that I would encourage everyone to try is true grasses and sedges. Most of these plants require a reasonable amount of sunlight but some of the sedges are more shade-tolerant. Carex species come in a variety of colours, and many are evergreen and grow in clumps, all desirable features. I am especially pleased with Carex morrowii, its variegated thick leathery leaves with white or gold edges, forming a nice low mound. My favorite of the evergreen true grasses is Festuca ovina glauca, ‘Elijah blue’, of similar growth habit. Calamagrosa overdam is a commanding grass with tall plumes of flowers. It is a variegated clumping grass that can be enjoyed until early spring before being cut back. Miscanthus sinensis, ‘morning light’, is also beautiful.
(3) Browse-tolerant plants
The final category of plants that are useful when gardening with deer is browse-tolerant plants. Some plants are so tough and fast growing that light browsing by deer helps reduce the amount of pruning required, once the plants have reached sufficient size. Choisya ternate (Mexican orange) is a lovely shrub that blooms twice a year with fragrant flowers resembling orange blossoms. It is very drought-tolerant and disease-resistant. I have three shrubs by the house, which only get browsed on the exposed side and we have to prune them at least once a year. A poor little Choisya shrub in the middle of the garden has taken many years to increase in size though, as it is nibbled from all sides. However it has now established itself and will require pruning.
Geranium macrorrhizum (cranesbill geranium) is the mainstay of my garden. This evergreen geranium is very drought-tolerant, grows in sun or shade, is disease and pest-resistant. It flowers in the spring and does not require deadheading. It is easy to remove if you wish to replace it with something more exotic. The deer do nibble it but are not interested in the flowers. Flower varieties include white and dark rose.
My final nominee of a tough fast-growing deer-resistant plant is Phormium tenax (New Zealand flax). Although the plant is closely related to daylilies, the leaves are more fibrous and evergreen. Deer ignore flax plants most of the time, although in the winter the deer have shredded some of the leaves in an attempt to bite them off. This damage can be pruned away in the spring. My flax have not yet bloomed so I can’t say if the deer like the flowers, which, borne on a tall stalk may be sufficiently out of reach.
I hope this will inspire you to try some gardening outside the fence. Good luck and happy gardening!