Neighborhoods with old, mature trees are often full of tree squirrels, and areas with rocky areas or lots of brush may have large populations of chipmunks—another member of the squirrel family. Tree squirrels (Sciurus spp.) and chipmunks (Tamius spp.) can be the bane of gardeners who like to plant spring-blooming bulbs, such as tulips. A large population of tree squirrels or chipmunks can make it virtually impossible to grow large numbers of tulips or some other bulbs, without extensive control measures. Because these rodents cannot digest cellulose material, they depend on protein-rich plant structures such as nuts and bulbs to survive. Gardeners are a squirrel's best friend since the squirrel's stock-in-trade is digging to hide (and find) nuts and plant bulbs. Experienced squirrels have known to sit and watch gardeners plant their bulbs, anticipating a feast. Fall bulb-planting season is especially difficult since this is precisely when other food sources are beginning to dwindle for squirrels.
Luckily, there are several things you can do to keep your spring-blooming bulbs in the ground where they belong.
Protect the Bulbs
One of the most fail-safe ways of protecting your bulbs from ravenous squirrels is to protect them with either chicken wire or hardware cloth. Hardware cloth is a metal mesh, much like chicken wire, except that it uses a smaller grid pattern, usually about 1/2 inch square. There are two general ways to use either chicken wire or hardware cloth to protect your bulbs.
The first method is to simply cut a section of either material to the overall size of your planting area and lay it over the top of the soil once you're done planting the bulbs. Secure it in place, either with stakes or by weighing it down with rocks or bricks. Then, cover it over with a mulch of shredded leaves or shredded bark mulch to hide the wire. The stems will come up through the holes in the chicken wire or hardware cloth, but the bulbs themselves will be protected from digging squirrels. This admittedly works best in open areas of your garden where you won't have to work around perennials or other plants.
The second method is to use chicken wire or hardware cloth to make simple cages from the wire mesh, place the bulbs inside, and plant the assembly in the garden. This is especially effective if you have tunneling animals in your garden, such as moles that also feed on bulbs.
Avoid Smelly Fertilizers
Bone meal, fish emulsion, and some other natural fertilizers have a pungent aroma that may attract many animals, including squirrels and chipmunks—not to mention digging dogs and cats. Avoid these natural fertilizers in favor of synthetic fertilizers that have no odor.
Plant Bulbs Among Other Plants
When spring bulbs are planted among established plantings of groundcovers or other perennials, squirrels have a harder time finding them and digging them out. Planted beneath an expanse of creeping vinca, for example, bulbs are usually ignored by squirrels. Another advantage is that the spring bulbs will supply early color to bare areas, and the yellowing foliage will then be covered over as the summer perennials begin to mature.
There are several natural, organic repellents on the market. Don't just limit yourself to squirrel or rodent repellents; organic deer repellents will work, as well. Another natural repellent that works well against squirrels is red pepper flakes. A liberal sprinkle of red pepper flakes over the area you've planted will do a good job of keeping hungry squirrels from digging there.
Add Sharp Gravel
If you're planting small areas of bulbs or planting a few bulbs in an established garden bed, you may want to consider adding some sharp gravel to the top and sides of your bulb planting holes. Squirrels don't like trying to dig through the sharp gravel, and they will usually give up once they encounter it. You can find sharp gravel in home improvement centers or landscape supply yards—it is often used to provide drainage under paved surfaces.
Crushed oyster shells, which have an unpleasant gritty texture, may also deter squirrels from digging.
Provide Alternate Food Sources
The theory behind setting up a squirrel feeding station is that if the squirrels have their own little buffet available, they won't bother trying to dig up your bulbs. Your squirrel feeding station can include dried corn cobs and peanuts. This is a controversial strategy, as some experts say that such methods merely attract more squirrels to your yard, where they will dig up your bulbs anyway. In areas where squirrel infestations are especially heavy, it may even be against local ordinances to feed squirrels and other wild animals.
This method may be worth a try if other methods fail, especially if you enjoy wildlife viewing anyway.
Disguise Your Planting Areas
When you are finished planting your bulbs, be sure to pick up any papery bulb husks, bad bulbs, or other debris. Such materials attract the attention of squirrels, who will start digging to see what other goodies you've left lying around for them.
Plant Bulbs That Squirrels Don't Like
Squirrels are very fond of some bulbs, such as tulips and crocus, but there are other spring-blooming bulbs that squirrels don't like. You can either replace your tulips entirely with these bulbs or mix them in among the tulips. A few bits of some bitter-tasting bulbs may send the squirrels away from your yard entirely. Good bulbs for deterring squirrels include:
Delay Planting Time
The squirrel and chipmunk feeding frenzy peaks in early autumn, but begins to quiet down a bit by mid- or late October, when the rodents have already stored away most of their winter supply. If possible, plant your spring-blooming bulbs somewhat later in the fall, when squirrels are no longer desperately filling their stores.