Garden Basics - Bulbs |
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Calculating the Number
of Bulbs to Buy
Timing Spring Bulb Planting
Getting Started With Tulips
Calculating the Number
of Bulbs to Buy
National Gardening Association Editors
Bulbs can be planted in containers, be mixed with other plantings, or just grow in a bed by themselves. If you want to create the stunning look of a massed planting of one kind of tulip or daffodil, you first need to figure how many bulbs should you buy.
Tools and Materials
• Shovel
• Rake
• Soil amendments such as compost
• Sulfur or lime
• Trowel or bulb planter
• Hose
Counting your bulbs. To simplify your bulb-buying calculations, we created this table of the most popular bulbs and their planting density in various-sized beds. Just measure the size of your bed and decide which type of bulb you want to plant, and the chart will determine how many bulbs you should buy. Of course, depending on both the effect you're trying to create and your budget, you can adjust the actual number of bulbs you plant. For example, for the most dramatic and showy effect, buy more bulbs than indicated and plant them closer. If you're mixing other bulbs in the bed to provide contrast to the main flower variety, buy fewer bulbs and plant them farther apart.
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Bulb |
10 |
25 |
50 |
100 |
Anemone, Crocus, Muscari, or Scilla |
200 |
500 |
1,000 |
2,000 |
Daffodil (large) |
75 |
205 |
420 |
1,100 |
Daffodil (small) |
140 |
340 |
675 |
1,350 |
Tulip (large) |
65 |
180 |
360 |
725 |
Tulip (species) |
75 |
205 |
420 |
1,100 |
Selecting bulbs. When selecting bulbs, remember that the larger the bulb, the more flowers it will produce the first year after planting. For the most dramatic effect, plant only one variety. If you want to stagger and elongate the flowering period, plant early, midseason, and late-season varieties of the same type of bulb, and group them by bloom season.
Planting bulbs. To create a bulb bed, till the bed and remove rocks, roots, and weeds (and sod if area is still lawn), then amend the soil with a 3- to 4-inch layer of compost. Based on a soil test, adjust the pH to between 6 and 7. Spread a granular bulb fertilizer (9-9-6) on the planting area.
Space the bulbs evenly apart in the bed, but avoid arranging them like soldiers in a straight line; staggered spacing will give the bulbs a more natural look when they bloom. Follow the planting depths suggested for the various bulbs. A good rule of thumb: plant in a hole three times as deep as the bulb's greatest diameter. Water the bed well.
After the show is over. After flowering is finished, let the foliage yellow naturally before cutting it back, and plant annual flowers such as zinnias or marigolds in the bed to provide summer color. Be careful digging in the bed so not to disturb the bulbs. (Note: Many gardeners plant tulips for one springtime show only because bloom in succeeding years is rarely as dramatic. Therefore, especially in the case tulips that you don't expect to rebloom, pull faded leaves immediately after flowers fade.)
Tips
For a longer show, you can plant two types of bulbs on top of each other in the same bed. Plant smaller bulbs such as crocus on top of larger bulbs such as tulips. Dig the bed to the depth of the larger bulbs. Plant and cover these with a thin layer of soil. Place the smaller bulbs on top and cover these bulbs to the soil line.
If rodents such as voles or mice are widespread in your area and have been known to eat bulbs during winter, consider lining the bottom and sides of the bed with wire mesh before planting. Lay wire over the bed once planted, too. Remove the top wire mesh in spring.
Photography by NationalGardening.com
Timing Spring Bulb Planting
National Gardening Association Editors
While it may seem strange, spring-flowering bulbs need to be planted in fall in order to bloom come show time. The bulbs need a certain amount of time to get established before winter's freezing weather sets in, and they need enough time exposed to cool soil temperatures to be properly chilled. But fall doesn't occur at the same time on the calendar in San Antonio, Texas, as it does in Minneapolis, Minnesota. So how do you know whether to plant in September or November?
Tools and Materials
• Shovel
• Mulch (hay, straw, or shredded leaves)
• USDA Climate Hardiness Zone map
USDA hardiness zone map. The simplest solution is to use the USDA Climate Hardiness Zone Map as your planting guide. This map breaks the country into 11 growing zones based on average annual winter minimum temperatures. First use the map to find which hardiness zone you live in. Then follow the table below to know when to plant spring-flowering bulbs in your zone.
Hardiness Zone |
Average Annual Winter Minimum Temperature |
When to Plant |
Zone 1 |
below -50° F |
Early September |
Zone 2 |
-50 to -40° F |
Early September |
Zone 3 |
-40 to -30° F |
September |
Zone 4 |
-30 to -20° F |
Late September to early October |
Zone 5 |
-20 to -10° F |
Late September to early October |
Zone 6 |
-10 to 0° F |
Mid-October |
Zone 7 |
0 to 10° F |
Early November |
Zone 8 |
10 to 20° F |
Early November |
Zone 9* |
20 to 30° F |
Early December |
Zone 10* |
30 to 40° F |
Mid-December |
Zone 11* |
Above 40° F |
Late December |
* Additional chilling may be needed to grow spring-flowering bulbs in these regions.
Special planting considerations. In coldest areas (USDA Climate Hardiness Zones 1 through 4), bulbs grow and perform best if planted early enough (September) to get established before the ground freezes. Mulch the bed a month after planting with a 3- to 4-inch layer of hay, straw, or shredded leaves. This will allow the soil to stay warm enough for the bulb roots to get established and will protect tender bulbs from freezing injury during winter, especially if the snow cover is sparse.
Bulbs in warm areas. In warmest-winter areas (zones 7 through 11), select bulb varieties that are best adapted to warm winters, such as wild tulips that are native to southern Europe. Most large-flowered tulips, hyacinths, and crocus will need supplemental chilling. To chill the bulbs before planting, place them in the refrigerator crisper for 8 to 10 weeks (but keep bulbs away from fruits or vegetables; they give off ethylene gas, which can cause the bud inside a bulb to abort), then plant. Since the ground rarely freezes deeply, if at all, in these areas, bulbs can be planted into December or even early January.
Tips
Even within a given climate zone, fall temperatures can vary widely from year to year. A good rule of thumb is to plant spring-flowering bulbs when the soil temperature 6 inches below the surface is below 60° F.
Bulbs that were not planted in fall at the proper time can be forced indoors this winter (see how-to project on forcing paper whites) or, if the ground still isn't frozen, planted in the garden. Depending on the severity of the winter, bulbs planted out late in the season may not flower the following spring.
Getting Started With Tulips
Michael MacCaskey
No other flower heralds spring like a tulip, especially after months of dreary, not to mention cold and snowy, weather. Like a river of clear, cool water on a hot summer day, my mind's eye feasts on the color and shape of tulips in early spring. If, like me, you need to see tulips bloom at winter's end, now is the time to buy bulbs and get them planted. Tulips are fun and enormously satisfying. To grow them, no expert's touch is required, and you don't need a large garden.
This article is for those of you who haven't had much experience with tulips or would appreciate a refresher. I hope it also offers a bit of inspiration. There is some basic how-to and a chart of the 14 types of tulips with some of the best varieties of each. A sense of these types and their characteristics goes a long way toward simplifying catalog and nursery shopping. And to make your planning even easier, I've listed some of the best combinations of tulips, as well as tulips to combine with annuals, perennials and other bulbs, so that you can make artful displays of complementary colors and bloom seasons.
Buying and Planting Tulips
Start by purchasing quality bulbs from a mail-order supplier or from a well-stocked garden center. The bulb exporting business in Holland is tightly regulated, so only top-quality bulbs are shipped. For most varieties, this means bulbs that are about 1 1/2 inches in diameter or 12 centimeters in circumference. Bulbs of some species tulips are much smaller. Choose bulbs that are firm and free of defects such as cuts, bruises or white mold. Expect to pay between 30 and 70 cents per bulb, depending on the season, the variety and the dealer. Generally, the earlier you order or the more you buy, the cheaper the bulbs.
Tulips like cold winters, so they're more challenging in the mild-winter West and South. In these regions, choose varieties that are proven in warm climates, usually the mid- to late-season bloomers such as the Darwin Hybrids and most of the late tulips do well. Likewise, in Gulf Coast regions, I'm told that the Darwin Hybrids are most reliable. Reasons? Their stocky stems are fairly tolerant of wind and rain, and the midseason blooms usually appear before the worst spring weather.
When to Plant
Plant tulips anytime the soil six inches deep is 60 degrees F. or colder. In the North and Midwest, this means September or October. Wait a month, then lightly mulch the planted area. This will give the bulbs time to break dormancy and begin growth before the soil freezes. The mulch protects them if snow cover is light or nonexistent before severe cold.
In the South and West, plant tulips during November and December. In the Deep South and Southwest, wait until after Christmas, when the soil is coldest, and plant deeply--to eight inches or more. Deep planting minimizes the superficial temperature fluctuations that occur closer to the surface.
If you live in zones 8 or 9, you'll need to chill the bulbs in your refrigerator crisper for at least eight weeks before planting. In the South, for instance, you'd buy bulbs in early November and plant in early January. Place them in a vented paper bag and away from ripening fruits that produce ethylene gas, which destroys the bud within the bulb. Chilling is not necessary for gardeners who live in zones 3 to 7.
Where to Plant
Tulips grow best in full sun in a location that has well-prepared, well-drained soil. Avoid planting in low-lying, shaded locations that might be prone to a late frost. In southern regions, however, planting in shaded areas may help keep soil cool longer, slow bulb growth and prolong bloom. Plant naturalizers, listed as "wild species," by the handfuls in rock gardens or in perennial borders.
How to Plant
Loosen and amend soil to a depth of one foot and add one pound of a low-nitrogen fertilizer, such as Bulb Booster, per 100 square feet. Minimum planting depth is twice the height of the bulb, or four inches of soil on top of the bulb. Planting deeper, to eight inches, discourages bulb multiplication and subsequent weakening and places the bulbs out of the way of pests such as voles.
Plant five tulip bulbs per square foot or 250 bulbs in 50 square feet, spacing bulbs about five inches apart. Tamp the soil and thoroughly water. Don't water again, or only sparingly so, until leaves appear.
Planting bulbs pointed end up is preferred. Only by planting all the bulbs the same way can you expect even height at bloom. Label groupings by name, and in cold climates, mulch.
Planting in Containers
Provide the maximum amount of space for root growth by placing bulbs so that tips are just covered by the soil surface. In cold climates, cover containers with about eight inches of mulch or store them in a cold garage or basement.
After four months, if you can see roots growing out of the drainage holes and top growth has emerged from the soil, you can move pots to a brighter, warmer location to force early bloom. You can also hold the pots in a cool but bright location and allow bloom to come at the natural time.
In warm climates, the process moves much faster. Store pots outdoors in the coldest location available. After eight to 10 weeks, begin checking for root growth emerging from drainage holes, then move pots to a warmer location for bloom.
When Tulips Bloom
Spring comes to different regions at different times, so when your tulips bloom will depend on where you live. All of the descriptions here are based on USDA zone 6. In regions warmer than zone 6, they bloom earlier, and in colder areas, they bloom later. In zones 8 and 9, peak tulip season is March to early April, while in zones 6 and 7 it's April. In zones 4 and 5, tulips bloom closer together, mostly in May. A case in point are the Darwin Hybrids 'Gudoshnik' or 'Parade'. They bloom in late March in San Francisco (zone 9) and six weeks later--early May--in Connecticut (zone 6).
The tulip season is longer in the South than it is in the North. Specific varieties of tulips that bloom at the same or nearly the same time in the North may bloom weeks apart in the South. But tulips don't grow as tall in these southern zones. A variety that reaches 30 inches in zone 5 may flower at a 20-inch stem height in zone 9. Microclimates play a role, too. 'Angelique' in a sunny area with a sunny exposure will bloom earlier than the same bulbs planted in a shady location.
How long the flowers last is determined by weather. In Holland, where spring is long and cool, tulip flowers last up to six weeks. Three to four weeks is more common for most of the U.S., and less than a week is the norm in the South if the flower has the temerity to open during a heat wave.
Care After Bloom
If you planted one of the naturalizing tulips (a type that comes back year after year), it's important that you allow leaves to ripen" thoroughly before cutting them off. This means letting leaves grow, mature and wither naturally. These growing leaves supply the bulb with energy for next year's bloom. Tulip bulbs that you do not expect or want to bloom next year can be pulled and discarded anytime after bloom. In fact, it's much easier to do this before plants wither than after. If you leave these bulbs in place, they will produce at least a few straggling tulip leaves the next spring.
Tulips as Cut Flowers
Cut tulips early in the morning. Look for flowers with tight buds that show color in the upper two-thirds of the exposed petals. For longest stems (and if you're growing them as annuals), pull the stem at the base. Indoors, recut stems and soak them for two or three hours in lukewarm water treated with commercial preservative solution. Wrap flowers with newspaper (kept dry) while stems soak.
Problems
The main reason tulip bulbs fail in the North is poor root growth prior to severe cold. In order to survive severe cold, the bulbs must have extensive root systems. If tulips are planted very late in the fall shortly before severe cold or if they are planted in very dry soil, they become susceptible to frost damage. Less commonly, extreme soil conditions, such as very low or very high pH, and poor water drainage will inhibit bulb growth and cause the bulbs to rot.
Pests
Aphids colonizing leaves, buds or flowers are a nuisance and cause a general weakening of the plant. If they appear in your garden, wash them off with clear water; if that isn't effective, try soapy water. Rodents of various kinds love tulip bulbs. Sprinkle fine, sharp gravel around each bulb to discourage voles. Or shake bulbs in a bag containing cayenne pepper prior to planting. The only sure remedy, though, is to plant bulbs in individual wire baskets, and protect plants with lightweight covers or netting.
Tulips to Combine with Other Tulips
These combinations match colors, bloom season and height to maximize impact.
Early
Showwinner' (red) with 'Candela' (yellow)
Showwinner' with 'Red Emperor')
Stresa' (yellow and red) with 'Plaisir' (red and white)
Midseason
Boccherini' (maroon) with 'Hibernia' (white)
Burning Heart' (ivory with red) with shorter 'Ice Follies' (ivory with pink)
China Pink' with 'Parade' (red)
Esther' (pink) with 'Shirley' (white with purple)
Golden Apeldoorn' (yellow) with 'Apeldoorn' (red)
Golden Parade' (yellow) with 'Parade' (red)
Negrita' (purple) with 'Esther' (pink)
Late
Angelique' (pink) with 'Mount Tacoma' (creamy white)
Grand Style' (dark pink) with 'Queen of Night' (maroon)
Menton' (pink) with 'Maureen' (white)
Menton' with 'Black Parrot' (dark maroon)
Pink Supreme' with 'Black Parrot' 'Renown' (rose) with 'Blue Heron' (lavender)
Tulips to Combine with Other Bulbs
Plant the lower-growing bulb (listed first) in front of the taller one (listed second).
King Alfred' daffodil with 'Couleur Cardinal'
Maureen' (white) with Fritillaria persica
Mrs. John T. Scheepers' (yellow) with Fritillaria persica
Muscari armeniacum with 'Hamil 'Blue Spike' with 'Couleur Cardinal'
Queen of Night' (maroon) with Fritillaria imperialis 'Lutea'
Tulipa sylvestris (yellow and green) with Muscari latifolium
Tulips to Combine with Perennials
Beauty of Apeldoorn' with basket-of-gold (Aurinia saxatilis)
Maureen' (white) with brunnera (Brunnera macrophylla)
Mrs. John T. Scheepers' (yellow) with Siberian wallflower (Erysimum hieraciifolium)
Orange Emperor' with leopard's bane (Doronicum cordatum)
Sweet Harmony' (yellow) with 'Blue Bunting' columbine
Tulipa bakeri 'Lilac Wonder' with blue fescue (Festuca ovina 'Glauca')
Tulipa pulchella (red) with Waldsteinia ternata
Any of the Double Early tulips with forget-me-not (Myosotis sylvatica)
Any of the medium-long white or soft yellow tulips with forget-me-not (Myosotis sylvatica)
Most any tulip with white candytuft (Iberis sempervirens)
Tulips to Combine with Annuals
In warm regions, plant annuals at tulip planting time in fall. In cold regions, wait until weather moderates in spring, or when you first see tulip buds emerge from the soil.
Angelique' (pink) with 'Imperial Pink' pansy
Menton' (pink) with 'Carmine King' (pink) forget-me-not
Mrs. John T. Scheepers' (yellow) with Chinese forget-me-not (Cynoglossum amabile)
Bulbs
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