It is the last day of November, and all but the most sheltered dianthus, marigolds and gazanias are still in bloom. Gardeners in Pennsylvania and New Jersey know they have a small window of time left to plant for next spring’s garden show. Temperatures this fall have been above average, and a hard frost is not yet in the forecast for at least a couple more weeks. Those who are a little late getting to one of the garden’s last tasks before winter still have a short time to plant spring bulbs before consistently freezing temperatures arrive.
Ideal conditions for planting spring bulbs are widely considered to be when the soil temperature is around 55 degrees Fahrenheit. However, many bulbs, as well as corms, tubers and rhizomes can still be planted well into December, provided the soil is workable. A crumbly soil that is rich in organic matter will allow well fed spring shoots to reach the surface unimpeded. Healthy bulbs are heavy for their size, without cracks, mildew or brown spots. Some bulbs have a papery sheath around them, which should be left in tact, but be sure to check that there is a firm bulb within, and not simply a handful of crispy shell.
Choose a location that receives at least 6 hours of sun daily and has good drainage. Plant bulbs in groups for greater effect. Planting depth should be 3 times the size of the bulb, so if a bulb has a diameter of 2 inches, then plant it 6 inches deep, with the roots facing down and the pointed end facing up. In some cases, it is difficult to determine which end should face up, so try laying the bulb sideways, which will usually still allow it to shoot. Make sure the soil around and underneath the bulb is soft enough to allow the roots to grow easily and to prevent it from rotting during rainy periods. Hard clay or rocky soil will inhibit the roots’ ability to set a firm foundation and may cause the bulb to sit in a wet bed after heavy rainfall.
Though not known to dig up well established bulbs, squirrels can take a liking to freshly planted spring bulbs. After planting, cover the bulbs with about 2 inches of mulch, to prevent squirrels from digging them up, and to provide a barrier between the cold air and the soil. Laying spent marigolds, pruned rose bush or barberry stems, or lavender branches over the site can also serve as a deterrent to these industrious little creatures. Deer are known to love feasting on tulip flowers, though they usually don’t bother with other spring bulbs like daffodils, hyacinths, crocuses, and grape hyacinths, so consider your choice of bulb and the ease of access that wildlife may have to your yard before planting.
In our area, tulips prefer a sheltered, sunny spot in order to stand a better chance of flowering each year. Whatever the bulb, it is important to allow the foliage to die back naturally after blooming, so that the bulb can be nourished by the returning nutrients. Since the die back process can look a little unattractive, think about placing bulbs among other plants that will help to distract the eye while the bulb leaves are decaying. Groundcover such as pachysandra and periwinkle (vinca minor) can divert attention, as well as hosta, astilbe and creeping evergreens.
Here are some suggestions for bulbs and similar flowers that can be slipped into the ground at the end of the season:
Lily of the valley
Snake’s head fritillaria
Starflower (lpheion uniflorum)
Star of Bethlehem (ornithogalum)