Deer can be a nuisance in gardens, as they will eat many common garden and landscaping plants. This often leaves gardeners wondering what they can plant that deer won’t eat. Alliums, which include decorative flowering plants like ornamental onions, garlic, and chives, are often recommended as deer-resistant plants. But do alliums really keep deer away? Let’s take a closer look at the evidence.
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What are alliums?
Allium is a genus of flowering plants that includes over 850 species. Some of the most popular alliums include:
– Ornamental onions – Globemallow onion, daffodil garlic, drumstick allium
– Garlic – Elephant garlic, Society garlic, Creole garlic
– Chives
– Leeks
– Scallions/green onions
– Shallots
These plants are known for their characteristic onion/garlic smell and flavor. They contain sulfur compounds that give them their pungent aroma and taste when their leaves or bulbs are crushed. Many gardeners grow alliums like chives and garlic for cooking, but several ornamental allium varieties are also popular for their large, vivid, ball-shaped flower heads in colors like purple, white, pink, yellow, and blue.
Why are alliums recommended for deer resistance?
Alliums are frequently recommended as deer-resistant plants because deer generally avoid them. There are two main reasons why alliums are thought to deter deer:
Strong odor
The strong scent of alliums, which comes from sulfur compounds in the plants, is believed to act as a repellent to deer. Deer have an excellent sense of smell, so the pungent aroma of alliums may be offensive or unappealing to them. Garlic and other alliums contain similar sulfur compounds to rotting meat and feces, smells that deer instinctively avoid.
Irritation from sulfur compounds
In addition to having an unpleasant odor, the sulfur compounds in alliums can cause irritation to a deer’s sensitive nose, eyes, and mouth if eaten. So alliums may deter deer due to their physical irritation and not just their strong smell.
Evidence that alliums repel deer
There are several sources of anecdotal and research evidence that suggest alliums do help repel deer:
Gardener reports
Many gardeners report that allium plants, especially ornamental onions and chives, are rarely touched by deer in their gardens. The plants emerge ungrazed even when planted near other attractions like roses and tulips that get eaten.
University studies
Research studies from universities have found that deer avoid eating some alliums:
- A study from the University of Maine Cooperative Extension found chives were avoided 98% of the time by deer.
- Research from North Carolina State University reported that society garlic and chives suffered little deer damage, while garlic, leeks, and Egyptian onions had moderate damage.
- A study by University of Rhode Island Master Gardeners observed no deer grazing on large stands of wild chives or wild garlic.
Expert recommendations
Many horticulture experts recommend alliums specifically for deer resistance:
- The Missouri Botanical Garden lists chives, garlic, and ornamental onions as “rarely damaged” by deer.
- The University of Maryland Extension suggests garlic, chives, and society garlic as deer-resistant plants.
- Washington State University includes chives, garlic, leeks, and onions on its list of deer-resistant plants.
Use in commercial repellents
Garlic and other allium extracts are common ingredients in commercial deer repellent sprays and granules. Products like Bobbex, Deer Off, and Repels All contain garlic as an active ingredient. The fact that garlic is thought to deter deer in these products lends support to the idea that live allium plants may also repel deer.
Evidence that alliums do not repel deer
Despite the anecdotal and research evidence above, there are some conflicting reports that indicate alliums may only provide moderate protection at best from deer or that they are not a reliable deterrent:
Mixed results in research
Some university studies have found mixed results regarding deer resistance:
- A Rutgers study saw wild garlic suffer moderate to severe deer damage at times.
- Research from the University of Wisconsin-Madison noted deer browsed ornamental alliums like garlic chives and society garlic despite nearby untreated plants being damaged.
Damage reported by gardeners
While many gardeners say alliums go untouched, others report moderate to severe grazing damage on garlic, chives, and ornamental onions. Individual deer preferences may vary.
Varying properties among alliums
There is significant variation in the sulfur compounds and aroma between different allium species and cultivars. Milder alliums may not be as effective at deterring deer. The onion family also contains edible members like onions, leeks, and shallots that deer may be more likely to eat.
Effects fade over time
As alliums grow and age over a season, the potency of the sulfur compounds may decrease, making the plants more palatable to deer later in the year. The aroma of alliums also dissipates more quickly once plants are cut or damaged.
Other factors that influence allium deer resistance
Whether or not alliums repel deer may depend on other factors as well:
Hunger level of deer
Extremely hungry deer during times like winter or drought may be more likely to overcome their aversion to alliums and eat them despite the undesirable taste and smell. Deer deterrents can lose effectiveness when deer have no other food sources available.
Individual deer preferences
Deer have personal tastes that can vary from the rest of the herd. A deer unbothered by the smell of alliums may graze on them while other deer avoid it. Persistent deer may adapt to alliums over time if continually exposed.
Availability of other forage
If other attractive, non-allium plants are present nearby, deer are less likely to eat the less palatable alliums. But alliums surrounded by only other unappealing plants become a more likely target by default.
Deer population size
In areas with high deer pressure and large herds, deer may be more willing to tolerate alliums to find sufficient food. With lower deer densities and abundant resources, avoiding alliums is easier.
| Factor | Effect on Allium Deer Resistance |
|---|---|
| Deer hunger level | Higher hunger makes deer more likely to eat alliums |
| Individual deer preferences | Some deer may like alliums more than others |
| Availability of other plants | More options make deer less likely to eat alliums |
| Local deer population size | Higher populations make deer more likely to eat alliums |
Conclusion
The majority of evidence indicates that alliums do provide some amount of deer resistance compared to other common garden plants. However, they are not a 100% guarantee against deer grazing. How effective alliums are at deterring deer seems to depend on factors like the specific allium type, time of year, deer population pressure, and availability of other food choices. While alliums likely offer moderate protection from deer, they should be combined with other deterrent methods for best results. Some options include fencing, repellents, scare tactics, and interplanting with less-preferred plants. Despite their limitations, alliums remain one of the best plant choices for reducing deer grazing in gardens and landscapes. Their deer-resistant qualities combined with their ornamental merits make them a wise addition to gardens plagued by deer.
