Bulbs: Fall Planting For Spring Flowering
Bulbs might be the ultimate 'plant and forget' flowers. They're relatively affordable, grow reliably in their first year, and many continue to flower for years, often multiplying as they go.
Planting spring-flowering bulbs in the fall (autumn) is ideal because it gives them time to establish their root systems while temperatures are cool. Most bulbs will keep growing roots as long as the ground stays above 40°F (4–5°C), which gives many gardeners plenty of time to plant as the main growing season winds down. For some gardeners, like those in the Desert Southwest, bulbs can be reliably planted all winter depending on your frost cycles.
In this article, we'll talk about spring-flowering bulbs, some tips for planting, and then some design ideas that will help you have a wonderful display of color come springtime.
In this article, we will use bulbs as the main term, but the advice also refers to corms and tubers unless otherwise noted.
Advantages of Fall Planting
Fall planting is good for many reasons. In addition to the cooler air temperatures, the soil is also more consistently moist. Bulbs need good soil contact to establish properly, and steady moisture, cool temperatures, and consistent ground conditions all help.
Popular choices of bulbs include tulips, daffodils, hyacinths, crocus, snowdrops, and alliums.
The shorter days and dewy mornings also reduce ground evaporation and add a consistent supply of fresh moisture to the soil, which reduces plant stress.
Many spring bulbs, including tulips and hyacinths, need a period of cold (usually 12–16 weeks) to flower well. If your winters stay mild, you can pre-chill these bulbs in a paper bag in the refrigerator before planting. Keep them away from fruit, especially apples, as the ethylene gas fruit gives off can damage the flower buds. Many daffodils and alliums need less chilling and are a good choice for warmer areas.
Planting Tips
Most bulbs prefer rich, well-drained soil; a good sandy loam is ideal. You can get a good feel for your soil by digging a few inches down and rubbing a small handful between your fingers. It should feel cool and damp, and loosely compact together as you rub it, but stay a little crumbly at the edges.
Because bulbs don't like having 'wet feet', avoid low spots or heavy clay soils. It may be necessary to raise an area up to improve drainage, or to amend the soil completely in the planting area and a few feet beyond to create even growing conditions.
If you have time, you can do a percolation (drainage) test to see how well your soil holds water. You can find a guide here: Testing Soil Drainage
Nutrients
A bulb already holds everything it needs to flower in its first spring, so feeding is mostly about keeping it strong for the years after. Avoid adding high-nitrogen fertilizers, as this promotes leafy growth at the expense of future flowers. A balanced, slow-release bulb fertilizer mixed into the soil below the bulbs at planting will encourage strong root development.
Planting Depth
For most bulbs, planting at a depth of 3 times the height of the bulb, measured from the base of the bulb, is ideal. This protects the bulb from adverse weather conditions, gives it plenty of access to damp, nutrient-rich soil, and promotes healthy root growth at planting and vigorous stem growth later on.
Plant bulbs with the pointed end facing up. If you can't tell which end is which, look for dried roots on the flat end and plant that side down, or plant the bulb on its side and it will find its way.
Always check the recommended planting depth for each bulb. Some, like Anemone blanda, prefer to sit shallower, while tulips are often planted a little deeper to help them come back year after year.
Watering and Mulching
Water bulbs thoroughly after planting to settle the soil around them and get roots started. After that, they generally need little extra water unless your fall is very dry. In colder areas, a few inches of mulch over the planting area helps keep soil temperatures steady through freezes and thaws.
A Quick Health Check
Before planting, it's important to check that bulbs are healthy. Occasionally, you may find bulbs that are rotten, shrivelled, or damaged by pests. Here's a list of what to look out for:
What you want:
- Plump bulbs with intact skins. The skin can be loose and papery.
- Bulbs that feel firm and solid, with about the resistance of an onion.
- Bulbs with a reasonable weight for their size. Many flower bulbs are light anyway, but if a bulb feels hollow, it's probably no good.
What you want to avoid:
- Shrunken, shrivelled bulbs with heavily damaged skins.
- Soft, slimy, or discolored bulbs, which can indicate rot.
- Bulbs with holes, tunnels, or chewed patches, which indicate pest damage.
- Bulbs that smell musty or sour.
Light surface wrinkling is common and perfectly healthy; it's bulbs that are shrunken or soft that you want to avoid. Bulbs that are small but undamaged are also fine, though they may skip flowering in their first spring while they grow.
Protecting Bulbs from Critters
Squirrels, voles, and other animals love to dig up and eat tulips and crocuses. Covering new plantings with chicken wire until the ground settles can help, as can planting bulbs that animals tend to leave alone, like daffodils and alliums. Tucking a few of these among more vulnerable bulbs can offer some protection.
Design Ideas
Bulbs can create a visually striking display of color when planted en masse or in groups, but this can be adjusted depending on the effect you want.
Informal / Naturalized Planting
For dense, clustered showings, plant more bulbs and have them closer together. For a more woodland or meadow-style effect, scatter their planting a little more and spread them out. A popular technique is to gently toss a handful of bulbs and plant them where they land. This creates a natural, informal look.
Formal Planting
Formal plantings of bulbs are often done in rows. Using a string tied between two stakes can help you get evenly spaced lines. Bulbs grow to predictable heights, so plan your planting with shorter plants in front and taller plants behind, while also considering the flowering time for your growing area.
Formal plantings look good with a cohesive color scheme. White is an excellent choice as an anchor color. Analogous displays of pinks, reds, and purples are striking, as are complementary displays of yellow and purple.
Layering and Succession
For a longer season of color, combine bulbs that flower at different times: early crocus and snowdrops, mid-season daffodils and hyacinths, and late tulips and alliums. You can even plant them in the same spot in layers, sometimes called 'lasagna planting', with the largest, deepest bulbs at the bottom and the smallest near the top. As one layer finishes, the next comes up through it.
After Flowering
Once your bulbs have finished blooming, resist the urge to tidy them up right away. Remove spent flower heads if you like, but let the foliage die back naturally for about six weeks. The leaves are feeding the bulb for next year's flowers, so cutting, braiding, or tying them back too early is the most common reason bulbs fail to flower again.
Wrapping Up
With a little planning this fall, bulbs reward you with some of the earliest and most reliable color of the year. Choose healthy bulbs, give them well-drained soil and the right depth, and then let winter do the rest. Come spring, you'll be glad you did.
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