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13. Salable Plants from Cold Frames, Hotbeds, Lath Houses

You can grow any plant to perfection in a properly regulated greenhouse, but there may be times when you need all of your greenhouse space for selected pot plants or other specialties. If you are faced with this predicament, grow your annuals, biennials, and perennials in cold frames, hotbeds, and lath houses.

You can add to the efficiency of these setups by giving the plants growing in them the same timely care you give your greenhouse-grown plants. But, since it is easier to control tem­perature, light, and ventilation in the greenhouse you will have to give even more attention to these details when you grow plants in frames and lath houses.

HOW TO USE THE COLD FRAME

You may want to grow plants directly in the cold frame. If so, scoop out 10 to 12 inches of the existing earth and replace it with about 4 inches of gravel or pea rock (to insure drainage) followed by good greenhouse soil filled in to within 6 to 12 inches of the sash-cover. Short-growing plants such as pansies, ground covers, and border plants should be planted in the front of the frame. Taller growing sorts, such as gilia, hollyhock, kniphofia should be planted at the back of the frame.

A better method is to make your original plantings in flats and place them inside the cold frame. These, of course, are portable and easily removed when you want to sell from them or bring them into the greenhouse for potting up.

During the first warm days of spring, you will have to venti­late the frame by raising the sash-cover a crack or so in mid-morning and then more as the sun continues to heat the air in the frame. Close the top in mid- or late afternoon, just before the temperature starts to decline, to conserve the warmth.

During winter, in my area, the plants need no water. As spring advances, they need only a slight watering on warm sunny days. As in the greenhouse, this watering should be done in the morning so the plants are dried off before nightfall.

In late spring and summer, it will be necessary to paint the glass with shading, or use wooden slatting to protect plants from direct sun.

When the weather warms and seedlings have grown sturdy, start hardening them off by opening the frame wider each day or by replacing the glass top with lath.

Following are thumbnail sketches of some reliable money­makers to grow in a cold frame.

Forget-Me-Nots (Myosotis sylvatica)

For Valentine's Day, forget-me-nots are traditional. But they sell well all spring, in pots or flats. They are popular for plant­ers, too, alone or with single or double-flowering pink, red or white wax begonias.

For growing in frames, plant the seed in July or August in flats of rich porous soil. Thin seedlings so they are spaced about 4 inches apart. They make rapid growth during cool fall days. Protect the frames with mats during winter. In late December, bring the flats into the cool greenhouse, water them and, when growth shows, pot the plants. They will be flowering and ready to sell for Valentine's Day.

If you prefer to sell them for spring bedding, leave them in the frame all winter. Then late in February or March, depend­ing on your area, remove the mats from the frame to admit some light. In the North, plants will not need watering until late March or early April when you can sell directly from the large flats or, if you prefer, transplanted to smaller flats. (Of course, you can also grow forget-me-nots—from seed to finished plant —in the cool greenhouse.)

Pansies and Violas

Pansies and violas can be grown through their entire cycle in the cold frame. They are good sellers for chain stores, road­side markets, or potted singly in 2-inch pots as a specialty for Mother's Day. Pansies are large and attractive, but the smaller-flowered violas bloom more profusely and for a longer season.

Sow seeds in mid-July in flats of loose, rich soil. Protect the frames during winter. When days warm up in late March or early April, remove the protection. Both pansies and violas bloom soon after the ground thaws.

Hardy Cyclamen

Strictly a specialty, hardy cyclamens are closely related to Cyclamen indicum of the florists' shops. They can be grown from seed sown in the cold frame in late September. It can be profitable to devote an entire frame to them, leaving them in it until they reach flowering size or selling them out of the frame before they reach maturity. When the weather warms up in spring, start watering and ventilating the planting. Cyclamens form minute underground tubers before showing top growth. As the leaves appear, shade from the sun.

Instead of growing them the whole year in the frame, you can plant them in 3-inch pots and plunge in a shady garden corner or set them in the lath house for the summer, returning them to the frame for wintering.

Primroses

Hardy primroses such as the orange-flowered Primula bulley-ana, yellow and red P. beesiana and alpine varieties, like the blue-purple P. denticulata and rosy-flowered P. cortusoides, can be grown from seed to maturity in the cold frame.

Sow from May to July in light soil, covering with about )i inch of sifted soil. Keep moist and shaded until germination occurs. As plants grow, pot them up in 2-inch pots of rich, humusy soil. For early spring sales, shift to 5-inch pots in September and grow on in a cool greenhouse. If you don't want to give them greenhouse space, winter them over in the frame and pot them in 5-inch pots after the ground thaws and new growth shows. Primroses can also be sold from flats.

Delphiniums

Perennial—or biennial—delphiniums which flower the sec­ond year after planting, are prized for borders. The annual sorts which flower from seed the first year are not so popular. You can sell perennial delphiniums in large or small flats or offer them in Ferto-Pots or the newer Jiffy-Pots made of peat. The buyer can plant them pot and all in the garden and the pot will slowly disintegrate in the soil to let the roots come through.

Sow seed directly in a frame or in flats when the temperature is around 55 degrees, either spring or fall. Keep the soil well moistened during germinating and after seedlings appear. Pro­tect the frames with mats during the winter. When growth shows in spring, water well, ventilate the frames, and give the plants an all-purpose fertilizer.

Delphiniums like an alkaline or sweet soil. If you sow early in spring, give seedlings a light application of garden lime at least twice during the summer. Fall-planted seeds need liming the following spring.

Hollyhock

In July, sow this favorite for background plantings about M inch deep in the cold frame. Pot up the plants the following spring and grow on in the frame or in a cool greenhouse.

There are singles as well as doubles with colors from purest white through lemon yellow, apricot, pink, and into dark red. If you find something especially desirable among your seed­lings, you can propagate it by root division in the fall, since seedlings do not usually come true to color. If rust infects plants, clear it up with a sulphur dust.

Canterbury Bells (Campanula medium)

Canterbury Bells are biennials, producing foliage growth the first year and flowers the second. Many gardeners like to pur­chase these as year-old plants which will flower the same season they are planted, so you will find a ready market for them.

Sow seed directly in the frame and grow plants on there until the following March, when they should be potted up in equal parts of loam, peat moss, and leaf mold and grown on in the cool greenhouse.

To avoid rot, be sure the soil is porous and well drained.

Oriental Poppies (Papaver orientale)

A wide floral color range—from flashy hues to pastels—is offered by the Oriental poppy, a fine subject for both spring and fall sales. Plants can be grown from division to maturity in the cold frame. Popular varieties include White Splendor, pink Spring Morn, salmon-pink Perfection, deep red Claret, and pastel Raspberry Queen.

While they can also be started from seed, you will get better varieties more rapidly if you purchase some choice large plants and divide them for your stock. When you plant, dig holes about 3 inches deeper than the length of the roots. Hold plants in the hole so roots are upright with crowns about 3 inches be­low ground level. Fill in soil up to the crown's level. Water well and then you can forget the plants until green leaves appear in fall. The larger the division, the sooner it will flower. Plant an 8-inch division in the fall and it will bloom the following spring.

You can also propagate these poppies from root cuttings which form leaves at the upper ends and roots at the lower ends. So save all the root trimmings (at least 3 inches long) from the divisions. They'll produce small plants which you can also sell, though at a lower price than the big grown-on divisions.

Good Bedding Annuals

All popular bedding annuals are good sellers and can be grown in the cold frame as well as in the cool greenhouse. Sow them in flats about 4 to 6 weeks before outside planting time in your locality. In Minneapolis, we sow annuals in frames about April first and later sell them right from the planting flats. These are some of the popular kinds:

ANNUALS BY COLOR

WHITE
Ageratum mexicanum album
Dwarf Phlox
Flowering Tobacco
Petunias
(varieties    Popcorn,    Pale­face, White Magic)
Poppies
Sweet Alyssum
YELLOW
Calendula
Cosmos
Marigold
Nasturtium
Zinnia
BLUE-PURPLE
Ageratum mexicanum
Bachelor Buttons
Browallia
Forget-me-not
Lobelia
Morning Glory
(variety Heavenly Blue)
Petunia
(varieties Blue Lace, Blue
Lustre) Phlox
Sweet Peas Verbenas
PINK AND RED
Clarkia Cockscomb Morning Glory
(variety Scarlett O'Hara)
Gaillardia picta
Moss Rose
(Portulaca) Petunia
(Fire   Dance,   Red   Satin,
Sugar Plum) Poppy
(Pink Champagne) Salvia coccinea
GREEN-FLOWERED
Annual Poinsettia
(Euphorbia heterophylla) Bells of Ireland
Schedule for Bulbs

The small greenhouse operator cannot successfully compete with large commercial growers in the production (or with dime stores in the selling) of hardy spring-flowering bulbs in pots. But if, after observation, you feel there is a potential market in your area, you should find potted spring bulbs a good sales item.

In late August or September (or even October), plant hardy hyacinth, tulip, narcissus, or some of the little bulbs such as crocus and scilla, in pots of greenhouse soil. Water thoroughly and bury the pot 1 to 2 feet (depending on winter tempera­tures in your area) in the ground. Cover to ground level with straw and leaves. In February or March, bring the pots into the cool greenhouse and water them. With Dutch hyacinths, keep the top growth shaded with an inverted flower pot. As top growth elongates remove the shading.

Bulbs left over from spring sales should be planted in the garden; retaining all the foliage and roots. They should bloom in a year or two. Do not use them the next year for forcing.

Other Uses for the Cold Frame

You can use your cold frames as winter storage quarters for newly purchased chrysanthemum, hemerocallis, iris, and rose plants. When these arrive too late to become established in the garden, it's good insurance to winter them in the frame.

I use one end of the frame for growing hemerocallis seed­lings. When the frost disappears, I transplant the seedlings directly to the cold frame. Here they stay through the following winter. After that they are planted into the garden.

If you hybridize amaryllis or other amaryllids, you will find it practical to summer the seedlings in the frame. Here you can easily attend to watering and fertilizing chores.

Use the cold frame in the spring for starting cuttings of perennials like carnations, chrysanthemums, delphiniums, and gerberas. Once rooted, they can be potted and sold or transferred to your garden to be grown and sold as specimen plants. Then there are cuttings from shrubs such as mock orange, blue-flowered caryopteris (Blue Mist), and hydrangea, among others, which will root and winter well in the frame.

46, 47, 48, 49. A quartet of profit-makers valued particularly as dried material for winter bouquets: Celosia, Pampas Plume (top left); Limonium sinatum or sea lavender or sea pink, often listed as statice (top right); Bells of Ireland (Molucella laevis) (bottom left), and the huge Ricinus,  Crimson Spire.   (Courtesy, Bodger Seeds and W. Atlee Burpee)

OPERATING THE HOTBED

Regulate hotbed temperatures so the soil is 5 to 10 degrees warmer than the air; this encourages heavy root growth and stocky plants. Most plants and seeds start root growth at 70 to 80 degrees. All need proper ventilation, watering, and shading.

Transfer to the hotbed any of the spring bedding plants you have started in the greenhouse; use the hotbed for starting summer-flowering bulbs; to hasten growth of flowering annuals or vegetables; for propagating cuttings of perennials; or for starting herbs from seed or cuttings.

Tubers, Bulbs, and Corms

Bury potted tuberous begonias, caladium, tuberose, tigridia, and other tender summer-flowering bulbs in the hotbed soil. Start with a bottom heat of 70 to 75 degrees and, as strong leaves appear, decrease the bottom heat to 65 degrees.

Perennial Cuttings

If you have wintered perennials in your greenhouse, take cuttings in early spring and transplant them into the hotbed, directly into the soil or into pots plunged in the hotbed. Most of them form roots easily making salable plants by mid-May. The following perennials are among those that are readily propa­gated from cuttings: chrysanthemums, clematis, dahlias, holly­hock, lobelia, penstemon, phlox, plumbago, and sedum.

Herbs in the Hotbed

There are not many herb specialists and with cookbooks and magazine articles stressing the value of herbs in cooking, gardeners have shown a renewed interest in them. Thus they may appeal to you as a specialty crop.

These herbs are especially popular: balm, basil, borage, coriander, caraway, parsley, rosemary, sage, and sweet mar­joram. (Other herbs, page 295 ff., can also be handled in the hotbed.)

Sow herb seed April 1 to May 15, ¼to ½ inch deep, directly into the hotbed or in flats. Give bottom heat of 70 to 75 de­grees. When the plants have their second set of good leaves, transplant to small pots or thin them and grow them on in the flats.

Schedule for Annuals

All annuals can be boosted into early growth in the hotbed. However, you should determine whether gardeners in your area are ready and willing to purchase them early, before you spend additional money starting them this way.

Sow the seed in flats, pots, or directly into the hotbed. Fine seed such as petunia is sprinkled on top the soil or other grow­ing media with but a light covering of sand sprinkled over it. Larger seeds—daisy, castor bean, etc.—are planted ¼ to ½ inch deep.

In addition to the annuals mentioned in other sections of this book, these, too, are good sellers and easily grown in the hotbed: African daisy, angel trumpet, balloon vine, blue lace-flower (Didiscus), cardinal climber, cup-and-saucer vine, fire­cracker plant (Cuphea), flax, lupine, salpiglossis, and statice.

Vegetables in the Hotbed

Most small greenhouse operators do not find it profitable to grow and sell vegetable plants. But you should at least find out about the possible market for them in your area. If sources of supply are short, you may add considerably to your greenhouse earnings by selling vegetable plants grown in the hotbed.

If you intend to grow the plants to marketable stage, be sure to keep them growing uniformly and as rapidly as possible without soft straggly growth. Careful watering and ventilation are among the greatest good-growth factors. If the plants ap­pear to be growing too rapidly, decrease water and give them more ventilation.

Tomatoes

If you live in one of the warmer areas you can plant tomato seed from January to late February. In the North, seed planted in the hotbed in early March makes salable plants for late May.

Speed germination by having the soil temperature 70 to 75 degrees F. Once the seedlings appear, reduce the temperature 10 degrees. Germination takes place in less than a week. Given strong light and moderate watering, seedlings will grow stocky and are ready for transplanting to the cold frame 2 to 3 weeks after planting.

Approximately the same culture can be applied to several other popular vegetables—eggplant, peppers, cabbage, canta­loupe, cucumbers, and summer squash. Check your local market for the possibilities of profit.

LATH HOUSES

In the South

A Florida grower uses his lath house for growing many ges-neriads, caladiums, camellias, palms, potted kaempferias, and other salable plants.

He engages in both local retail and mail-order selling, and to him this garden structure is as useful as a second greenhouse. From a flat slatted roof hang dozens of baskets of achimenes (his specialty). During the winter the achimenes rest and the small rhizomes are stored indoors.

On benches, grow pots of caladiums, bird of paradise (Strelitzia regina), unusual arums such as amorphallus, rare callas for collectors, and several kinds of kaempferias. His ship­ping season is finished by October 1 and the only items remain­ing at that time are stock plants to be used for propagating.

In California

California is famous for its gorgeous tuberous-rooted be­gonias, and a large percentage of this crop is grown in lath houses. To conserve room the hanging basket types are sus­pended from the ceiling. Other kinds grow directly in benches, in pots set on staging (steps), or shelves; some are planted into the ground.

Tuberous begonia seeds planted in November make flower­ing plants by spring. During the interim, when it is too chilly for the seedlings to be outdoors, they are usually grown in the greenhouse—many of them being grown in plastic covered greenhouses. Staggered plantings of tubers from February until April produce flowers for most of the spring and summer.

Large commercial growers in California store the tubers in refrigerated or specially constructed and cooled cellars at 50 degrees F. The smaller grower plans his stock so he'll have few tubers to store and these usually can be stored in a basement or a cool closet.

In the Midwest and North

A Kansas grower who specializes in sales of potted vines and trailers, propagates her plants in a basement fluorescent setup.

When the weather is mild, she moves the plants to the lath house. In the lath house are top and side hooks for the plants. Moss-lined baskets of achimenes and columneas hang from the ceiling. Many varieties of ceropegia and episcias are grown on the sides. Here, too, are strawberry begonias, asarina, philo-dendron, and ivy.

Another Kansas grower who specializes in rex begonias and ferns starts all of her plants in the cool greenhouse. In April they are moved to the lath house. She sells both retail and through the mail. The lath house provides such a beautiful set­ting for these plants that it is easy to sell them to visitors.

A grower in our area has made a lath house of discarded fluorescent light tubes. In it she grows for sale tuberous be­gonias and trailing geraniums. And in the shade of this same lath house she works at her favorite hobby, grafting shrubs and trees.

A Missouri grower uses the lath house for summering orchids. During the winter they are grown under fluorescent light and in a tiny greenhouse extended from the basement. Early in April the orchids are moved to the lath house. Here they remain until late fall.

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