In temperate regions with four seasons, autumn is a great time to prepare gardens for next spring. Adding bulbs to flowerbeds in the fall should result in lovely blooms after the spring thaw.
Spring-flowering bulbs are planted in autumn because they're hardy in colder temperate climates and they require a cool dormant period of at least 8 to 12 weeks before they can produce flower buds. The planted bulbs develop roots until the ground freezes. If you live in a warmer climate, spring-flowering bulbs can be forced in a refrigerator at approximately 40ºF–50ºF (above freezing) for at least 8 to 10 weeks, or until signs of growth are apparent.
Bulbs can be planted until the ground is frozen or no longer workable. Daffodils and narcissus should be planted earlier (beginning of September to late October). Other bulbs, especially tulips, can be planted from early September through to mid-December, as long as the ground is not frozen solid.
When purchasing bulbs, look for good-sized, firm ones—these will produce the best blooms. Discard any that show signs of rot, are soft, or crumble when squeezed.
The majority of bulbs prefer well-drained soil that's neutral to mildly acidic (pH 6.5). Heavy clay soils aren't suitable unless they've been amended with organic matter. When planting, the soil should be damp, but not wet—bulbs are highly susceptible to fungus and mildew diseases, which spread in excessively wet conditions. Bulbs planted in poorly drained soil are likely to rot or develop botrytis blight (gray mold), which is a felt-like mold that covers the scales of bulbs and causes stunting, dieback and distorted growth. Tulips are especially susceptible.
Holes can be dug with a trowel or spade, but there are a variety of specialized tools available.
A bulb auger that attaches to a hand drill is useful for mass plantings. Its shape is similar to a large drill bit. It features a spiral-cutting blade at the base, and a metal protrusion called a whip, which assists in measuring the appropriate depth of the hole and pushes away the excess soil. If you're planting among other, established growth, this tool does a good job of cutting through fibrous roots.
A bulb planter is a cylindrically shaped tool that removes a core of soil at the correct planting depth. After positioning a bulb in the hole, you can use the planter's plunger to replace the soil and cover the bulb.
Plastic bulb baskets have slits in the sides and bottom, allowing for proper air circulation and drainage, which helps prevent bulb rot. The bulbs can be arranged in the basket and the entire thing can be planted in the ground. Bulb baskets make it easier to plant several bulbs at a time, and they're easy to dig up once the foliage starts to die back. (This is useful if they are in an area that will be planted with annuals in spring. The bulbs can easily be dug up and the stackable baskets can be used for storing them.)
Bone meal or slow-release bulb fertilizer should be placed in the hole before planting. Lightly mix the fertilizer with the soil. Be sure to follow the package directions, which vary depending on the planting area.
For established bulbs that are left in the ground each season, you should top dress the soil with bone meal and mix thoroughly using a cultivator every couple of years.
As a general guide, plant larger bulbs like tulips, daffodils and hyacinths six inches deep and six inches apart. Smaller bulbs like crocuses (which are actually corms—short, solid underground stems covered in papery leaves) and grape hyacinths should be planted three inches deep and three inches apart. Planting at the maximum recommended depth helps to protect bulbs from moisture loss during intense heat and also helps deter predators (squirrels love tulips).
Planting the bulbs in the right direction is key. For pointed bulbs such as tulips, daffodils and hyacinths, ensure the pointed part faces up toward the sky and the flat part faces down into the ground. If you can't tell which end is which, plant it sideways—this makes it easier for the plant shoot and roots to grow in the correct direction.
Generally, bulbs are left in the ground for the next season. Even when the plant is in decline, its leaves continue to process food; therefore, it's important not to disturb the leaves until they have died back naturally and the bulb goes into dormancy (usually six weeks after blooming has stopped). Until then, you should cut only the spent blooms. If the garden space will be used for annuals,the annuals may be planted over the bulbs, or the bulbs can be dug up (with their foliage intact) and stored in a garden shed, garage or secluded area of your garden until their foliage dies back naturally. They can then be cleaned and stored somewhere cool and dry for planting in the fall. It's good practice to dig up spring bulbs every third year.
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