When to plant bulbs

Bulbs aren't instant-gratification plants. They need some time in the ground before they send forth stem, foliage, and flowers. But they're not inert when they're in the ground, of course. They're generating root growth, which will help nourish the show as well as anchor the plants in place.

The following sections explain what different types of bulbs require, depending on when they bloom.

Planting spring-blooming bulbs

Spring-blooming bulbs require a chilling period. They're dormant when you get them and break dormancy only after the chilling. Winter conveniently supplies this necessary cold period! That's why you put the bulbs in the ground the fall before you want them to bloom.

Planting summer-blooming bulbs

Most summer-bloomers, such as gladioli, calla lilies, dahlias, tuberous begonias, and crocosmias, love warm soil and toasty summer sun. If you garden in a mild climate (Zones 8 to 10 — see Chapter 3), you can plant these bulbs in the early spring and expect flowers by summer. If you garden in a colder area, early spring planting isn't feasible. Instead, wait until late spring or early summer — the same time locals plant tomatoes outside — or start bulbs early indoors in a warm spot and care for them until danger of frost has passed; then you can move the plants outdoors.

In either case, regular doses of all-purpose fertilizer (applied according to label directions) can nudge your plants into faster, more robust growth and more and better flowers.

To get flowers earlier and longer from these summer bloomers, visit a nursery in late spring or early summer (or place your order then with a mail-order house, either via catalog or Web site) and buy a larger, pre-started plant.

Keeping your cool: The skinny on forcing bulbs

Forcing bulbs may sound cruel, but the term merely means that you're encouraging the plants to bloom early by treating them in a special way. You can force potted bulbs into early bloom, but they still need 8 to 16 weeks to chill (generally the larger the bulb, the longer the chilling time). Place the bulbs in the fridge, in an unheated garage that doesn't freeze, on chilly basement stairs, or in a cold frame (a wooden or concrete block box buried in the outside soil during the cold months). Some of the easiest and most popular bulbs to force are paperwhites.

As soon as you pot the bulbs you want to force, you have to keep them cool and the soil lightly damp. If the soil dries out, their roots won't form, and if the temperatures are too warm, the flower buds in the bulbs may end up being blind or will blast (they'll shrivel and never develop into full blossoms).

Forcing spring bulbs has two stages, and the first is the rooting period. For the rooting stage, place the potted bulbs in any cool (40-50°F), dark spot for 10 to 16 weeks. Some varieties take longer than others. Don't worry if the temperatures aren't in this range every day; the temperature range is just the ideal. The important point is that the bulbs are in a cool, not freezing, place to root. A refrigerator is perfect.

Tip: Before moving the potted bulbs to the next stage, look at the drainage holes in the pots.

Roots should be growing out of the holes; if they aren't, put the potted bulbs back into a cool, dark area until they are. One of the most common ways people fail in this game is by not allowing the bulbs to root sufficiently before going to the next stage. Alternatively, the bulbs may be ready to come out of the big chill when you see at least an inch of top growth and the bulbs don't move when you try to wiggle them by hand.

After the bulbs are well-rooted, you can move them to the growing-on phase, where the foliage starts to grow and the eventually bulb blooms. First, you want the bulbs to adjust to warmer temperatures and higher light, so place the rooted bulbs in their containers in a cool, bright spot that's around 60°F for a few weeks. Remember to keep the soil lightly moist. Next, move the bulbs to an area that's slightly warmer — mid to high 60s — and very bright to finish the plant's grow-ing-on cycle. A sunny, south-facing windowsill is fine. Turn the pots a quarter turn each day; otherwise, the stems will lean toward the light. You can also place the bulbs so their foliage is a few inches from a two-tube, or preferably four-tube, fluorescent light fixture.

The bulbs should bloom in about three to four weeks. The blossoms will last longer if you move the bulbs to a spot that's cool (in the lower 60s) and not quite as bright (without direct sunlight).

Planting fall-blooming bulbs

Spring gets all the attention, to be sure, but some bulbs bloom in fall, and they're gorgeous and easy to grow — and they're a wonderful sight to behold when the gardening year is winding down. Among this group are the autumn crocus (Colchicum autumnale — no relation to true crocuses — or Crocus speciosus), winter daffodil (Sternbergia), Guernsey lily (Nerine bowdenii), saffron crocus (Crocus sativus), and even a species of snowdrops (Galanthus reginae-olgae). If your local garden center doesn't have these, look for them in specialty bulb catalogs or on gardening Web sites.

Fall-blooming bulbs have a dormant period, too: summer. Thus, you ought to plant them in late summer — as soon as they're available — because the plants are ready to wake up. Some bulbs, like the autumn crocus, send up their leaves in spring and flower leaflessly in fall. Usually, these bulbs spring to life soon after planting — within a few weeks — though you'd best mark the spot so you don't forget them and plant something over them. In any event, the flowers will arrive on schedule.

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