In most regions, spring is announced by the blooming of spring bulbs in the landscape. Spring-flowering bulbs offer a colorful display when the rest of the landscape is still waking up from its winter dormancy, and best of all, they require very little effort to grow. The best results are achieved if you follow these simple steps for planting them.
When to Plant Spring-Flowering Bulbs
It's a standard rule of thumb that spring-flowering bulbs are planted in the fall, but the fall season stretches over 12 weeks, after all, and there's a notable difference between temperatures and soil conditions at the start of fall in late September and in late November.
The best time to plant will vary depending on the type of bulb and your region. Check with your local University Extension Service or a good local nursery for recommendations on when to plant a particular species. For example, in Minnesota, it's recommended that daffodils should be planted in September, while the recommendation in Tennessee is to wait until late November. The rule of thumb is to plant tulips in November (before the ground freezes) so that they don't send up foliage too early.
A good strategy that works for most spring bulbs is to wait until air temperatures are reliably below 50 degrees Fahrenheit and soil temperatures are at or below, 55 degrees Fahrenheit. Most spring-flowering bulbs can be planted all the way up to the point where the soil is frozen solid.
The fall planting rule for many classic spring bulbs—such as daffodils, tulips, hyacinths, and crocus—is based on the fact that they require a cold-chilling period of as much as 16 weeks to get ready for spring blooming. But if you live in a region where winters do not provide an extended cold period below 40 degrees Fahrenheit, you will have trouble growing these bulbs—unless you artificially chill the bulbs in the refrigerator for 10 to 12 weeks or buy the bulbs prechilled.
If you are a warm-weather gardener and don't want to go through the trouble of artificially chilling bulbs, then plant later-blooming bulbs, such as amaryllis, paperwhites, ranunculus, and anemones.
Before Getting Started
Avoid bulbs that appear withered, spongy, or moldy. In general, the larger the bulb, the larger the flowers it will produce. Smaller bulbs are typically less expensive but will have smaller or fewer flowers. However, when you are dividing an established group of bulbs, it's fine to save the small bulblets—just be aware that it may take a couple of years until they are vigorous enough to produce flowers.
Equipment / Tools
- Garden spade
- Hardware cloth or red pepper flakes (if needed for animal control)
- Spring-flowering bulbs
- Bone meal or balanced fertilizer
Choose the Right Location
Most flowering bulbs prefer full sun. But don't overlook a spot in your garden just because it's shady in the summer and fall. Spring bulbs flower early, before most deciduous trees have leafed out, so it's safe to plant bulbs around or beneath the canopy of shade trees. However, don't plant spring bulbs in an area with permanent shade, such as in the north-side shadow of a house, garage, or fence.
Woodland bulbs—such as Anemone nemorosa (woodland anemone), Arisaema (Jack-in-the-pulpit), Erythronium (dog's tooth violet), Galanthus (snowdrop), and trillium—prefer a bit of shade. Always check the cultural needs of bulbs before you plant them.
Consider Design Principles
Bulbs tend to look best when planted in large clumps or drifts, which gives them a natural appearance. To achieve this, either dig a large area and arrange many bulbs in the hole at once or simply toss the bulbs in the air and dig holes and plant wherever they fall. Some gardeners insist that planting groups of bulbs of odd numbers gives a more natural look to the landscape. But you should generally avoid planting in formal geometric rows unless you are deliberately aiming for an artificial effect.
Evaluate and Prepare the Soil
Bulbs don't like wet soil because constant moisture is likely to cause rot. This is especially true when the bulbs are dormant in the summer. So choose a planting site that has good soil drainage year-round, but especially through the summer. Many spring bulbs originate with species that are native to arid regions such as the Mediterranean or mountainous areas, and they will grow best in soil conditions that mimic those areas.
Bulbs already have the embryo of next year's flowers inside them, so there is no need to fertilize the bulbs as you're planting them. If the soil is poor, you can mix a small handful of bone meal or balanced fertilizer into the planting hole. In the spring when foliage is emerging, you can fertilize bulbs sparingly to help them form next year’s embryo.
Plant at the Right Depth
In general, bulbs should be planted to a depth of two to three times their height. For example, if a bulb measures 2 inches from nose to base, it needs to be planted 4 to 6 inches deep, For daffodils, the typical recommendation is to plant 6 to 8 inches deep. Interestingly, bulbs planted at less than ideal depths will often self-adjust within a year or two, increasing their depth in the soil.
Place the Bulbs Right-Side Up
Many bulbs have an obvious up and down orientation. The pointed end of a bulb is generally the stem and should face up when you place the bulb in the planting hole. You might even be able to see some shriveled, hair-like roots on the flatter, downward end of the bulb.
Sometimes, though, it's difficult to tell which end is up. If so, simply plant the bulb on its side; the stems will generally find their way to the surface. In fact, even bulbs planted upside down will generally sprout and flower, though it may take them a few extra days.
Protect the Bulbs
Squirrels, chipmunks, and other rodents are notorious thieves of many spring-flowering bulbs. If you find this to be a problem, lay a small grade of chicken wire or hardware cloth over the bulbs in the planting hole before covering them with soil. These materials allow bulb stems and foliage to grow through but prevent rodents from digging up the bulbs.
Another method is to sprinkle red pepper flakes into the planting hole, which will deter rodents from digging up the bulbs. Or, you can limit your bulb selection to species that rodents and other animals tend to avoid, such as daffodils.
Mark the Planting Site
To make sure you don't disturb your bulbs by planting something else in the same spot after the bulb foliage gone dormant and died back, mark their planting spot. The marker can be as simple as a decorative stone, plant tag, or small wooden craft stick with the bulb name written on it. Or you can draw a garden map that carefully shows where each bulb group is planted.
Water the Bulbs Appropriately
Water the bulbs immediately after planting to settle the soil, close any air pockets, and get the root system growing. After that initial watering, let nature do the rest and don't apply water unless in times of severe drought.
During the growing season, water sparingly—or not at all. Many spring bulbs originate in relatively dry regions, so excess water is generally not a good idea. Through the fall and winter, you only need to water your bulbs during a particularly dry season. Come spring, you should be rewarded for your effort.
Employ Proper Aftercare
When your bulbs have finished flowering and the foliage has completely yellowed and died, gently pull or cut back the foliage to ground level. Resist the temptation to cut foliage while there is any hint of green. The foliage needs time to photosynthesize food for the bulbs. Cutting down foliage too soon prevents the bulbs from storing enough energy for next year's blooms.
Divide the Bulbs When Needed
Many bulbs multiply and produce more plants, which can make the planting site overcrowded after a few years. This is especially true of daffodils. If your bulbs aren't producing as many blooms as they used to, overcrowding might be the culprit. You can divide your bulbs when they begin entering their dormant period, usually just after the foliage completely dies back. Note that dormancy is brief, so don’t put off this task too long. Dig up and separate the best and biggest bulbs, and replant them according to spacing recommendations. Discard small and damaged bulbs.