How can I protect my garden from squirrels?

I had a big problem with squirrels digging up my tulip bulbs last year. Tulips are one of my favorite spring flowers, so I want to try planting them again this year. What can I do to protect the bulbs?

— Phil Nowicki, Morton Grove

Squirrels are a nuisance and frustration for many gardeners when the animals dig up newly planted tulip and crocus bulbs. They are attracted to the freshly dug earth after you plant your bulbs and can be difficult to deter. When they discover the disturbed soil, they investigate what is buried there and end up finding your bulbs versus a stash of nuts. The squirrels sometimes taste the bulbs and then just drop them somewhere in your yard. Squirrels are less likely to dig in a bed that has other well-established plants like perennials in it. Generally, the squirrels just dig up the bulbs the first year that they are planted, so you just need to get them through the first fall. I have had problems with chipmunks digging up my crocus in subsequent years after planting them, so I decided not to plant crocus.

A good way to protect your new bulb planting is to cover the area with chicken wire or plastic garden netting to prevent the squirrels from digging in the area. Stake the wire or netting in with landscape staples or use bricks to secure it on the surface of the soil. Then install a light layer of mulch if you want to hide it. The wire or netting can be removed in spring before the bulbs start growing. The chicken wire with 1-inch openings can also be put over the bulbs underground and then covered with soil. This will deter squirrels from digging while allowing the bulbs to grow through the wire and flower in spring.

Clean up the planting site when you are finished planting, since any bulb debris (like the papery tunics that fall off the bulbs) can attract squirrels and chipmunks. One option is to dip bulbs in liquid repellents that are available in garden centers before planting. I have also had success using granular repellents spread on top of the areas where bulbs are planted. Spread the repellent right after planting. In most home gardens, where bulbs are mixed in with other plants, it is not practical to cover the soil surface with netting to protect the bulbs. Avoid using mothballs, since they’re toxic when ingested and may add unnecessary toxins to your soil. A light layer of mulch will give the bulbs more time to establish roots and also helps to deter squirrels. Generally, squirrels will only dig a few inches beneath the soil surface, so plant larger bulbs like tulips deeper to provide more protection. Most varieties can be planted 8 inches deep.

Tulips and crocuses tend to be favorites for animals to eat. Try planting bulbs such as daffodils, ornamental onions, grape hyacinth, fritillaria, snowdrops, and winter aconite that are more animal resistant both after planting in the fall and in the spring when growth begins.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.