Posts Tagged ‘fall bulbs’

When to Plant Bulbs in Fall

Though they bloom in spring, flower bulbs that are planted in fall are known as “fall bulbs”. Popular spring-flowering plants like daffodils, tulips, crocus, and hyacinth are fall bulbs. Allium, scilla, anemones, and Asiatic lilies are planted in fall too. With a seasonal range of three months, when to plant fall bulbs is a question many gardeners struggle with.

Daffodils are a welcome sign of spring

Daffodils are a welcome sign of spring

Timely fall planting allows roots to develop before the ground freezes and prepares the plant for quick spring growth and flowering. If you plant too early the bulbs may use critical energy reserves and can begin to send up new shoots, exposing the young growth to winter kill. Prolonged exposure to warm, moist soil may promote fungal problems and rot. Plant too late and root growth may not be enough for the plant to flower properly.

To flower in spring, fall bulbs require exposure to cold temperatures. This chilling period triggers them to break dormancy when temperatures warm in spring. It’s all about planting early and warm enough for the bulbs to begin developing, but late enough for them to stop developing shortly after to start soaking in the cold.

Tulips need to be planted in fall

Tulips need to be planted in fall

There is no single right time for all gardeners. The proper time for planting fall bulbs may be September in Wyoming or North Dakota, October in Colorado or Kansas, November in Oregon or Nevada, and December in Virginia or North Carolina. Gardeners need to find out what’s right for their individual gardens; one-size-fits-all advice from gardening books or magazines may lead to incorrect guidance.

Cooler soil temperatures are a primary indicator for proper planting time.  Ideally, soil temperature needs to be below 60F; a temperature of 55F degrees is perfect. The problem for the average gardener is that few gardens come with soil thermometers. As a guideline, soil temperatures usually cool to this target after a few weeks of nighttime temperatures regularly between 40 and 50.

There are also natural indicators that some gardeners use:

Plant just after fall foliage peaks
Plant when you no longer hear crickets at night
Plant when you see flocks of birds heading south
Plant when you regularly need a jacket to work in your garden
Plant the week after you smell your neighbor’s fireplace for the first time
Plant when you have to turn your car heater on in the morning
Plant when your dog moves from the shade to the sun
Plant when your grapes are ripe
Plant on Columbus Day, Halloween, Veteran’s Day, or Thanksgiving (depending on your zone)
Plant garlic on the first day of school
Plant after you blow out your lawn sprinklers

These suggestions are very unscientific and rely on local conditions that may not match your climate. But if you find a natural indicator that works for you, use it.

Some gardening experts recommend planting bulbs six weeks before a hard, ground-freezing frost. That’s a little too hard to predict for many regions. If unseasonal warm weather lingers, bulbs may end up waiting in the ground for the cold to arrive for two months or more. That’s much too early.

Planting within a few days of your average first frost date is a good guideline. That’s what I typically use. The average first frost date means that historically half of first frosts occur before that date and half occur after. For me, that’s the first week of October. By that time cool nights have cooled the soil but there are still enough warm days ahead to keep the soil warm enough for root development.

Irises aren't true bulbs and do best when planted in late summer or early fall

Irises aren’t true bulbs and do best when planted in late summer or early fall

Check with local gardening experts for recommendations on planting fall bulbs. Diane Brunjes, Certified Colorado Gardener and the gardener for the Horticultural Art Society of Colorado Springs, recommends October planting versus September for our area too. In our climate, “It’s too warm early in the season,” she says. She’s right.

A little too late is usually better than a little too early. There is a four to six-week target window for planting bulbs, but as long as you can still work in the soil it’s probably not too late. Crocus, scilla, and snow drops do better planted earlier. Daffodils, hyacinth, and tulips can handle late planting. In fact, tulips can be planted in frozen ground and will probably still do fine.

If you miss the ideal planting time and still have bulbs you purchased, plant them anyway. Most bulbs will dry out and be worthless if left to sit in their bag over the winter. They stand a chance of growing while in the ground. Plant them and hope for the best; you may be surprised by the results.

If you’re still wondering when to plant your bulbs take a look around your garden. When you walk outside at night are you cold without a jacket? Have your pepper and tomato plants withered from frost? Are your raspberries fruiting? Are mum flowers drying on the plant? These are all signs that the season is changing and winter is coming. Don’t delay too long. It may be the perfect time to put those bulbs in the ground.

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How to Plant Fall Bulbs

Many of the most popular and most beautiful garden flowers grow from bulbs. Bulbs are grouped in two basic categories, fall bulbs and spring bulbs. The flowers they produce are generally spring flowers and fall flowers, respectively. Deciding when to plant is relatively easy: if it flowers in the spring, plant in fall; if it flowers in fall, plant in spring.

Daffodil and tulips

Crocus and tulips, the first colors of spring, come from fall-planted bulbs. These bulbs need to be exposed to long periods of cold temperatures to grow and flower properly. Planted in fall, they enjoy the winter cold in the frozen ground and burst to life when the warmth of spring raises the soil temperature. While not every spring flower from a bulb needs cold to bloom, it’s still a nice rule of thumb to follow. Plant spring flowers in the fall.

To support the flowers, the bulbs need to establish a root system. Planting in the fall allows the bulbs to develop the strong roots needed for quick spring growth. Plant bulbs when the soil begins to cool after the heat of summer. Roots will grow until the ground freezes so the earlier they’re planted, the more time they have to develop that system. Generally, this means at least six weeks before the first hard freeze. You want the soil to be warm enough to sustain root growth, but the conditions shouldn’t be so warm that foliage growth happens; that’s why we don’t call them “summer bulbs”.

If you delay and have bulbs in storage, having missed the perfect time to plant, it’s best to get them in the ground even late in fall or into winter. With time bulbs will dry out and when they do they lose the energy needed for plant growth. This year’s bulbs need to be planted this year. They may not develop a healthy root system before spring but at least they have a chance for survival.

Very warm regions, like Zones 8 and 9, can grow spring flowers from bulbs, but some of this timing needs to be modified. Most of the spring flowering bulbs, particularly hyacinth, crocus, and tulips, need cold saturation so the bulbs should be stored in the refrigerator for six to eight weeks before planting. The bulbs should be planted in early winter and treated as annuals; bulbs need to be re-planted each year. Either purchase new bulbs or dig up old bulbs and put in cold storage, but they need the cold temperatures to bloom again. Amaryllis, lilies, and daffodils don’t need the cold treatment.

The bulbs you choose should be large, firm, and show no signs of mold, fungus, or decay. Buying from reputable online sources or a local nursery or garden center where you can actually examine the bulb ahead of time is the best idea. Typically you get what you pay for. If you buy bargain bulbs from a discount online or mail nursery, you may get scrawny, dried out, damaged inventory; I know because it’s happened to me. Inexpensive bulbs in garden center bins can be fine, but examine them before you buy.

Tulip bulbs

While buying bulbs from the bulb capital of the world, Holland, seems appealing, be careful. Bulbs in the Netherlands are grown by the millions for export. The hybrids they’ve developed over the centuries are beautiful, but many have been selected for the big bulbs they produce to make importing them more appealing. Often the plants that result may not be best suited to your garden; they may not be able to sustain the energy needed to keep producing the beautiful flowers. It’s not unusual for foreign bulbs to produce plants that only survive one or two years.

Look to bulb producers that develop bulbs in a region similar to the one for your garden. Do a little research and select bulbs that are appropriate for your climate and plant growing zone. Don’t just focus on how pretty the flowers will be. The plant must survive your winter to bloom in spring.

When choosing a location for planting fall bulbs look for a sunny, well-drained area; bulbs don’t like wet feet. Be sure to look into the future. The sun needs to shine on the plants in the spring. Deciduous trees won’t have leaves in the spring and the sun’s position in the sky is different than fall, so areas that might be shaded in fall may be in full sun in spring, and vice versa.

Consider how you want to establish your bulb bed. Remember that fall bulbs bloom in spring and most of the flowers don’t last longer than a few weeks. For the entire summer and into the next fall, the area will be devoid of color as the foliage gradually begins to brown. Many gardeners prefer to intersperse other flowers in the same beds during that time. Whether annuals or perennials, having other plants in a bulb bed helps sustain continued color throughout the growing season.

If you’re developing a new bed it’s best to prepare the entire plot by amending the soil and adding a slow-release fertilizer to a large area all at once. The bulbs can be planted in the fall, grow and bloom in spring, and lay the framework for additional plants. At the appropriate time, other flowering plants can be placed among the bulbs.

If you’re adding bulbs to an established bed with other perennial plants already in place, you’ll need to plant one hole at a time. This is more time consuming, but follows the same basic idea of interspersing plants that flower at different times of the year.

With bulbs in hand, and the weather cooling, begin fall bulb planting. Generally speaking, use a “rule of three”. Plant bulbs about three times as deep as the height of the bulb and space them apart at least three times the width of the bulb. Some large daffodil bulbs may be almost three inches tall and thick (8 centimeters). Yes, they should be planted about eight inches deep (20 centimeters) with eight to nine-inch spacing. Keep this in mind when you buy mass-produced, bargain bulbs. The directions for planting tulips and daffodils were exactly the same for bulbs I bought at a garden center though the bulbs were markedly different in size.

You can use special bulb tools or the ones you have already. I have a bulb planter, a special cylindrical tool than is designed to twist in the soil and pull out a plug, producing a perfectly-shaped hole. If you want to buy one of these, look for one that has inch or centimeter markings so you know how deep you’re digging. I also have a trowel with depth markings. They both were a little more expensive than generic tools, but they come in very useful when I want to measure the hole depth for different bulbs.

My bulb planting tools

In a bed with other plants already in place, I lay out my bulbs ahead of time in the desired pattern on the surface. In a brand new bed you can dig a trench or large hole of the appropriate depth to place the bulbs in. Some gardeners like long, orderly rows of flowers. Others like clumps of flowers. Others like a totally random arrangement where the bulbs are tossed on the ground and planted where they land. I use all three methods and vary them depending on which bed I’m planting. Clumping or planting a lot of bulbs in one area is better than a few, single ones because the concentration of color can provide quite a visual impact.

Bulbs laid out for planting

Using the bulb tool or  a trowel, dig the hole, or prepare a trench. Place the bulb with the pointed end up. The flat end is wider and fatter and should be at the bottom of the hole.  With smaller bulbs it may be difficult to discern which is the base and which is the top; just put it in the hole and the plant will adjust when it grows.

Tulip bulb in the hole

If you weren’t able to amend the soil in the entire planting area, do it one hole at a time. Mix some compost and fertilizer with the soil at the base of the hole. While the bulb has all of the energy needed to produce a plant and flowers in the first year, slow-release fertilizer high in phosphorus (the second number on the box) helps with plant development in poor soil like mine. I use a triple phosphate fertilizer. If the soil has been amended and is rich with organic matter, fertilizer isn’t necessary. Avoid just adding the fertilizer directly to the hole because it can burn the developing roots.

After placing the bulb, cover it with amended soil and tamp down gently. You don’t want to compact the soil, just ensure it is completely covering the bulb. Especially after amending it you’ll have more soil than will fit in the hole with the bulb in it. That’s okay. You can mound it slightly because it will settle in time.

Covering the bulb with soil

That’s all there is to it. Dig a hole, place the bulb, cover with soil. As with most plants, adding mulch to the bed will help moderate soil temperature and avoid frost heave in the winter. Once in the ground, most fall bulbs have a long life ahead of them and you’ll have flowers every spring.

Be as creative as you want when it comes to planting fall bulbs. Generally, low plants are planted in front of high ones, but consider blending and mixing different bulbs in the same bed. When flowers bloom at different times they’ll provide an ever-changing spring portrait. Consider planting different bulbs in the same hole with smaller ones on top of large ones. When they grow and bloom the flowers will be mingled with each other for a distinctive look. Bulbs do well in pots too.

As easy as they are to plant and as beautiful as the flowers are, it’s hard to come up with an excuse for not planting fall bulbs.