Fall planting for spring flowers

Although the gardening season will soon be coming to a close, there is still one planting activity to be done: planting bulbs for spring flowers.

While it may seem odd to plant bulbs now, the reason is that spring-flowering bulbs need time to develop a solid root system before winter sets in. For best results, wait until soil temperatures are below 60 degrees F before planting bulbs. That means waiting to plant until mid-September or October.

You can buy bulbs at most garden centers, or if you have enough time, order them through catalogs. By choosing different varieties, you can enjoy spring flowers from late winter to early summer. For an early glimpse of spring, plant crocuses and snowdrops. Daffodils bloom next, followed by tulips, squill, and grape hyacinth. Indian hyacinths (Camassia) are some of the last, along with Summer Snowflakes (Leucojum).

When purchasing bulbs, buy only top quality bulbs — ones that are large, firm, and of good color. Cheap bulbs will only produce poor, or sometimes even no, flowers.

Choose a site that has good drainage and at least six hours of direct sunlight a day. If the soil is poorly drained, consider raised beds, or planting chequered lilies (Fritillaria meleagris). To prepare planting beds, dig up six to eight inches of soil. Add peat moss or other organic matter, then mix in fertilizer containing phosphorus such as rock phosphate, superphosphate, or special bulb fertilizer. If rodents, skunks, or other small mammals are a problem, bone meal will only attract them. You can help avoid digging problems by placing a fine wire mesh over the bulb bed. Or place sharply crushed rocks or shells you can buy for this purpose around bulbs at time of planting. You can find these at complete garden or feed stores.

I like to plant bulbs in groups or clumps rather than in rows. For a nice show of color, I plant bulbs in front of evergreen shrubs or among perennials and other flowering shrubs. Formal tulips look best planted in beds in symmetrical arrangements while daffodils should be planted in “naturalized” or informal plantings. A good method for informally arranging daffodils is to throw them over your shoulder, and plant them where they land!

Plant bulbs upright, pointed ends up, at the recommended depth. As a rule of thumb, bulbs should be planted three times as deep as the bulb’s greatest dimension. Use a shovel, trowel, or bulb planter, and space bulbs according to size. Large bulbs such as tulips and daffodils should be placed four to six inches apart while smaller bulbs such as crocus, snowdrops, and squill should be placed one to two inches apart.

When plants emerge in spring, fertilize lightly with bulb fertilizer at least two inches from the plant. Once flower petals fade, use scissors to remove the flower parts and stem before the plant produces seed pods. However, let the leaves remain until they have turned yellow, so the bulbs get plenty of nourishment for the following spring’s display. You can camouflage the bulb foliage by carefully planting summer annuals around the bulbs once all danger of frost is past. I often interplant daffodils among my perennials. This provides color before the perennials emerge, and then the new perennial leaves hide the dying daffodil leaves.

Although most spring-flowering bulbs are perennials, you may need to replant tulips and hyacinths each year as these blooms aren’t as vigorous the following bloom seasons. Daffodils, scilla, and crocus, on the other hand, are stronger and spread further with each bloom season, so are best left undisturbed.

If bulbs become overcrowded, with fewer and smaller flowers, they may need dividing. Under ideal conditions this may be every two or three years. The best time is when the foliage begins to turn yellow. Replant immediately, following the fertilizer and planting recommendations described above.

If you need to move perennial spring-flowering bulbs, it is best to do so after bloom before the foliage dies and you can’t find the bulbs! You can pot them, or “heel them in” planting in a group or in a row to allow the leaves to die back normally. To speed up the dying back of daffodil leaves, plus have them less floppy and unsightly, some gardeners double the leaves over and either tie them in a knot or with a rubber band. Just mark where the bulbs are so you can find them later.

Dr. Leonard Perry is Extension Professor, Department of Plant and Soil Science at the University of Vermont. Visit his website at www.uvm.edu/~pass/perry/index.html