Summer Bulbs

As a third-generation native of southern California, my gardening roots are deep in the mild-climate West. There, as elsewhere, most garden action occurs in spring. Invariably, come July and August, someone would ask which bulbs to plant for color and interest during those otherwise dry and hot months. I might have suggested tuberous begonias or dahlias -- summer stalwarts of gardeners everywhere. Or, in that climate, I might have just as well recommended tiger flower or rain lily, tender and lovely plants that thrive in zones 9 and 10 with little fuss.

But now that I'm in the Northeast, I've realized why not grow these "exotics" here too? If we northerners are willing to dig our glads and cannas and store them in the basement or garage, why not do the same with Acidanthera, Bletilla and Galtonia? There are so many wonderful but tender bulblike plants to brighten our gardens when the earth is baking and the rains retreat. Don't think of this kind of gardening as difficult -- it's no more work than planting annuals. The true lilies are an exception. They are hardy, so can be planted in fall as well.

Planting

Exactly when bulbs will appear in your local nursery depends upon your climate. All of the following are available from mail-order suppliers in January or February, and most through March and April. Plant large bulbs in a hole twice as deep as the bulb is thick. In other words, if the bulb is two inches thick top to bottom, plant it in a four-inch-deep hole. The same holds true for smaller bulbs, but it's okay to set them a bit deeper.

You'll see terms such as "corm," "tuber" and "rhizome." Although botanically distinct, all are handled in much the same way.

If gophers, squirrels or other animal pests are common in your area, planting tasty bulbs, such as lilies, in open soil is a waste of time. Protect them by planting inside a hardware-cloth basket.

Grow frost-sensitive bulbs in cold climates by planting the bulbs in large pots. Bury the pots into garden soil once it thaws and frosts are past. Lift them out again in fall before freezes.

Here are nineteen different bulbs to grow for summer blooms.

Acidanthera

Acidanthera (Acidanthera bicolor)

Consider fragrant and creamy white Acidanthera a more relaxed, more romantic gladiolus. (In fact, you might find this plant listed as Gladiolus callianthus.) Plant corms 3- to 4-inches deep, 6-inches apart in spring a week or so before the last frost. They'll grow 2- to 3-feet tall and bloom, depending upon your climate, in August or late September. Flowers are 2- to 3-inches wide, nearly 5-inches long and marked with either brown or purple blotches. They're long lasting as cut flowers. Corms aren't hardy, so you'll need to dig them in fall before soil freezes if you plan to replant.

Tuberous Begonia (Begonia)

Large flowers with neon candy-cane colors in every hue except blue, tuberous begonias are the most colorful of all the summer bulbs. Plants need bright light, cool temperatures and humid air to grow well. They thrive along the coast of California from San Francisco to San Diego, and likewise in the Pacific Northwest west of the Cascades.

Bloom begins early summer and lasts until frost. Flowers are categorized by their similarity to other flowers. Some are "carnation," others "camellia" or "roseform." Typical size is 3 to 4 inches in diameter. Most grow 12 to 18 inches high but some have a more spreading habit that's perfect for hanging baskets. Place tubers at soil level in pots or flats indoors in February or March. Bigger tubers flower better. Fertilize with diluted nutrients with every irrigation. Look for the upright or hanging Pacific Hybrid or Blackmore & Langdon strains, or more compact and smaller-flowered multifloras, which includes the heat-tolerant 'Non-stops'.

Chinese Ground Orchid (Bletilla striata)

Flowers are admittedly tiny compared to florists' orchids, but they are true orchids with all the shape and detail of a cattleya. Where winters are mild, plant in fall. Elsewhere plant bulbs as soon as soil is workable in spring, about one inch deep. Pale green, ribbed leaves are 12 inches tall; flower stems reach to 18 inches high. The 1- to 2-inch lavender or white ('Alba') flowers appear--sometimes a dozen to a stem--in late spring or summer for six weeks or more.

Fancy-Leafed Caladium (Caladium bicolor)

Gardens in Houston, Mobile, New Orleans and Tampa wouldn't look the same in summer without the color and texture provided by caladiums. All they need is warmth and shade. The plants grow 18 to 36 inches high. Plant corms about 1 inch deep and 8 inches apart in pots in March or May in the garden. Leaves variegated with white are most common, but there are also varieties with red, pink, silver and bronze coloring. Look for 'Freida Hemple' (red), 'Torchy' (red), 'Carolyn Wharton' (pink), 'Fannie Munson' (pink) and 'White Queen'.

Canna (Canna generalis)

There are few bulbs you can plant that, within a season, add an unmistakable feel of the tropics. Colors are hot yellow, orange, apricot, coral and red typically, though you can get white and ivory. Bloom begins in early summer and continues until frost. Leaves add to the picture, too. They're large and dark green or sometimes bronze-red. Heights vary between 18 inches and 6 feet. Plant rhizomes 2 inches deep, 10 inches apart, after danger of frost, in an area that receives full sun. Try clumps of single colors. Look for self-cleaning varieties such as the Freedom series. The old flower petals drop off rather than hang on the plant.

Crocosmia

Montbretia (Crocosmia)

Of all the bulbs listed here, this South African native is perhaps the most useful and least exploited by American gardeners. It blooms midsummer for at least four weeks. Colors are red, crimson-orange, orange and yellow. Once cut, 1- to 2-inch flowers on the 3-foot stems last two weeks. Plants overwinter reliably in Philadelphia and perhaps farther north if heavily mulched. Plant corms just prior to the last frost, about 1 inch deep and 2 inches apart. Afternoon shade is preferred in hot, dry areas. Plants grow 2 to 4 feet high. If you dig and store corms to overwinter, don't allow complete drying. Keep corms partially moist. Look for 'Lucifer' (red), Crocosmia crocosmiiflora (orange-crimson) or C. masoniorum (brilliant orange to orange-red on slightly shorter plants).

Dahlia

Dahlia

You must know about dahlias. They're colorful and agreeable daisies and make an always-welcome August bouquet. The variety of dahlias is immense. Smallest ones are about 6 inches high and the tallest are 6 feet. (An exception, the tree dahlia, reaches 10 feet and more.) Colors are nearly every imaginable one, except blue. Order the gray-brown tuberous roots now, and plant them after frost danger, in March or April. Dahlias need full sun and rich soil, in holes 1-foot deep. Give larger ones room to spread: they'll need 4 or 5 feet. Pound a strong 1- by 2-foot stake into the center of the planting hole, then set the tuber so that the developing bud is 2 inches from the stake and pointed towards it. Cover the tuber with soil; water regularly. Pinch side shoots of flowering stems to get the biggest flowers.

Freesia

These are fragrant and colorful pot plants increasingly favored by florists. In the mild-winter West, freesias are planted in the fall. But they remain available into February, although usually only as colors rather than named varieties. If you live in a cold climate, plant them now indoors. Grow them on a sunny windowsill, or simply keep them from freezing until March or April, then move pots to the garden. Plants grow about 12 inches high. Flowers are 2 inches long. Plant about 10 corms 1 1/2- to 2-inches deep in an 8-inch pot. Use well-drained potting soil. In low-light situations plants will grow taller and floppier, so use a thin wire or bamboo stakes in the pot for extra support.

Summer Hyacinth (Galtonia candicans)

Here is one of the summer bulbs I most want you to try. It is dramatic and fragrant and surprisingly hardy. Winter survival is pretty much a sure thing anywhere south of Philadelphia. In spring, summer hyacinth develops a clump of leaves, some of them three feet long. Midsummer, you'll see a thick flower stem begin. It reaches upwards of 4 feet tall, and is adorned with bell-shaped, 1- to 2-inch white flowers. If you plant in April, you'll have flowers in July. Set large bulbs 6 inches deep in rich soil. (In mild climates, plant in fall.) Cover with thick mulch to help bulbs through winter, or dig and lift bulbs after leaves die in fall.

Gladiolus

Gladiolus

There are few substitutes in floral bouquets for these tall, stately spikes. And they are so easy to manipulate in the garden: Plant a corm and harvest flowers 85 to 100 days later. By planting every two weeks for two months starting in April, you'll have staggered bloom until fall. In southern California, don't plant after late February to avoid summer thrips; in desert areas, plant November to February to avoid the heat.

Colors span a wide range: apricot, buff, cream, green ('Green With Envy' is new this year), lavender, orange, purple, red, rose and salmon. Individual flowers may be quite large--4 to 6 inches in diameter. Plant habits are variable, too, ranging between 1 1/2 feet (Baby Glads) and 5 feet (Super Novelty types). Cut for indoors just as lowest buds begin to open. Plant four times deeper than the thickness of the corm (five times deeper in light or sandy soil) and set a sturdy stake at planting time for taller kinds. In mild coastal regions, you can leave corms in the ground. Where soil freezes, dig and store corms once tops die back.

Blood Lily (Haemanthus)

This is an unusual--and very tender--bulb that really better suited to container growing than the garden. The plant is another South African native and is related to amaryllis. The most desirable species is H. multiflorus katherinae. If you can't find it, H. multiflora is similar and it costs less. Flower color combines red, coral and white; height is 6 inches to nearly 3 feet. Plant one large bulb to a 10- or 12-inch pot. Place it so the tip is right at the soil surface. Water lightly at first, until leaves appear. Broad, wavy leaves grow a foot or more long. Move outdoors only after danger of frost is past. After two months, a succulent stem emerges and grows upward for two feet. At its top is a cluster of salmon red flowers, each one with long, protruding red stamens.

Peruvian Daffodil (Hymenocallis narcissiflora)

In addition to a powerful fragrance, the most notable feature of this flower is the six, slender, petal-like segments surrounding the central cup of the flower. Flowers are about 4 inches across, including the narrow petal segments. They appear atop 30-inch stems in midsummer, usually 2 to as many as 5 in a cluster. Leaves are bright green, 2 inches wide and strap-shaped, and about 2 feet long. Plant bulbs 1-inch deep in rich, well-drained soil after the last frost. Allow at least 10 inches between bulbs. Peruvian daffodil also grows well in containers. One variety, 'Sulfur Queen', is a beautiful pale yellow.

Iris

Iris

There are so many wonderful irises. But I do direct your attention to two excellent species that you can buy and plant now for summer bloom: Japanese iris (Iris ensata) and Siberian iris (I. sibirica).

Japanese iris makes a four-foot-tall, early-summer-blooming plant. Colors include blue with purple ('Dazzling Tapestry'), purple ('Floating Cloud'), pink ('Pink Lady'), rose ('Rose Queen') and white ('White Queen'). In many cases, contrasting shades edge petals. Vertical leaves have a raised midrib. Japanese iris thrives at the edge of pools, ponds and streams, or in partially submerged pots. Plant rhizomes 2 inches deep and divide clumps in late summer, replanting the youngest ones for the clump's outer edge.

Siberian iris is not quite as tall nor available in quite as many color variations. Narrow, grassy leaves grow 2 1/2 feet high and flower stems reach 1 foot or so higher. Flowers are shaped more like a Dutch iris and usually appear in June, just as the bearded iris pass. Colors include blue, purple, purple-red and white; 'Caesar's Brother' is blue and 'Snow Queen' is white. All make excellent cut flowers. Plant rhizomes 1 inch deep and don't divide until the center of a clump stops growing.

Lily

Lilies

Lilies have an other worldly air about them. Perhaps that's why they are so often associated with royalty, purity or funerals. The genus includes more than 100 species and thousands of named varieties. Bloom time varies, of course, but is mostly early to late summer. The color range is orange, red, pink, yellow and white. Height varies between one and seven feet.

Many kinds of lilies are available in both fall and spring. Whatever the season, plant as soon as you can after receiving them. This is important because unlike most bulbs, lilies are never completely dormant. All lilies need loose, well-drained soil, plenty of moisture year-round, cool soil for roots and bright, cool sun for leaves. Gophers love to chew on lily bulbs. If they are active in your area, plant bulbs in wire baskets.

Not counting the Easter lily, the lilies that fit most peoples' image of this flower are any of the Oriental types. They make huge, fragrant, flat-faced flowers, eight inches or more wide. In most cases, flowers face outward; some face upward and some are semi-pendant. Most grow three to four feet tall and, surprisingly, do very well in containers. One of the best known is Lilium speciosum 'Rubrum' (red) and L. s. 'Album' (white). Hybrids between these and L. auratum, the gold-band lily, have produced popular varieties such as 'Casa Blanca' (nine inches, pure white) and 'Stargazer' (up-facing, red with white margins).

Nerine

This is a large group of amaryllis-like bulbs that are native to southern Africa. They present the most opportunities for mild-climate gardeners where plantings expand year after year. Where temperatures rarely fall below 20 degrees F., these make outstanding landscaping perennials. Depending upon your climate and the species, you can have nerine in bloom from August to January. Once established and given only a minimum of care, bulbs will survive and multiply for many years. If you live in a colder climate, they adapt readily to pots.

Nerine bowdenii is the most cold hardy of the group, tolerating temperatures to 10 degrees F. Its leaves are an inch wide and a foot long. Dark pink 3-inch flowers come in clusters of 8 to 12 atop 2-foot stems.

The Guernsey lily, N. sarniensis, makes clusters of 10 iridescent crimson flowers, also on 2-foot stalks. Several varieties are available. New ones include 'Cherry Ripe' (rose red), 'Early Snow' (white), 'Radiant Queen' (bright rose pink) and 'Salmon Supreme' (dark salmon pink).

Plant bulbs so that their tips are at the soil surface, and allow about 6 inches between the plants. In pots, use one per 4-inch pot and cover only the bottom half with soil. Wait for growth to begin before watering.

Tuberose (Polianthes tuberosa)

If you want fragrance in your garden, you must try tuberose. The intense scent is almost overpowering in a small room on a warm day. Tuberose has a long history in European perfumery, and before that in pre-Columbian Mexico as a chocolate additive. It is an agave relative that's native to Mexico. The plants love heat. Flowers are white, tubular and set along 3-foot spikes. Varying with your climate and planting time, expect flowers from July until frost. 'The Pearl' (double flowers) and 'Mexican Single' (single flowers, taller and perhaps hardier) are the only two varieties commonly available. Leaves are narrow and grassy. Bulbs are hardy to about 20F, meaning mild-climate gardeners can leave them in the ground and treat the plants like perennials. Elsewhere, treat them like tuberous begonias, starting them indoors early, then moving starts outdoors once soil is warm and frost is past. Or, plant in late June for bloom by September. Plant tubers 2 inches deep and 6 inches apart. Healthy tubers always show a greenish bud. Plants need steady warmth and sun or partial shade.

Tiger Flower (Tigridia pavonia)

Another common name of this bulb, Mexican shell flower, is more descriptive: Imagine beach combing and finding the most delicate, multicolored shell. Flowers are large--3- to 6-inches across--and divided into six segments, three larger outer ones and three smaller ones. Outer segments are usually a solid color--orange, pink, scarlet, white or yellow. Smaller segments are white but with dark blotches. You can buy mixes or separate colors. Each flower only lasts one day, but one follows the next for several weeks of midsummer bloom. Leaves are narrow and ribbed, 1- to 2-feet long. Plant bulbs 1- to 3-inches deep, 5 inches apart, after soil is warm and frost danger is past. They need full sun in coastal, cloudy or humid regions, afternoon shade in hot, dry areas. Performance is often better in northern gardens where summer night temperatures are lower. Plant bulbs in wire baskets to protect from gophers. Dig bulbs in fall and keep dry over winter.

Spring Calla Lily (Zantedeschia)

Unlike the common white calla lilies that are mostly available in the fall, spring callas are the more delicate and more colorful hybrids you've perhaps seen in florists' shops. Flowers are familiar-shaped calla flowers--a colorful 4- to 5-inch bract surrounding an upright spike covered with minute flowers. But instead of white, colors are light yellow (Z. albomaculata), golden yellow (Z. elliottiana), or pink (Z. rehmannii). 'Gem' is rosy lavender; other assorted unnamed hybrids include shades of apricot, orange and purple. In all cases, bloom appears late spring and early summer. Plants grow about 2 feet high. Spring callas need moderately acid soil, generous amounts of moisture with good drainage and a resting period. All are excellent in pots. Plant rhizomes about 2 inches deep, one per 6-inch pot.

Rain lily (Zephyranthes)

These charming, grassy-leaved bulbs take their name from their habit of blooming after a rain. Plant them in your lawn, between stepping stones, around trees and shrubs and in containers with larger plants. Wonderful naturalizers, they'll multiply, surprise and please you midsummer on for years. Height is 5 to 8 inches; colors are white, yellow, pink and rose. Plant tiny bulbs about 1 inch deep in spring after the last frost. Mulch heavily in fall, or if soil freezes, lift and store bulbs.

Michael MacCaskey is editorial director at National Gardening.

Photography by Suzanne DeJohn

Article published on June 23, 2008.

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