Running Your Green House Economically
The temperature you maintain in your greenhouse plays an important part in plant growth. Greenhouses are classified as cold houses (unheated), cool houses (55 to 60 degrees at night), or warm houses (60 to 70 degrees at night). Whenever night temperatures are cited you should figure on a daytime requirement about 10 degrees higher. Each of these three classes of greenhouses is suitable for growing certain kinds of saleable plants.
If you live where outdoor night temperatures never dip below 32 degrees, you can run a cold (unheated) greenhouse the year round. Otherwise, you might find it profitable to operate a cold greenhouse until late fall, close it down during the coldest winter months, then resume operations in early spring. In such a house, you can make money on annuals, spring-flowering bulbs, and bedding plants by forcing or starting them in late February or early March. The cold greenhouse is also an excellent place for growing lettuce.
In summer, use the unheated greenhouse for tomatoes, seedling perennials, or almost any plant that flowers in summer. In this type of greenhouse, winter-grown plants should be planted directly into the bench soil. Here they will withstand lower temperatures than if planted in pots. In the following lists are plants I have found profitable to grow under the various conditions specified.
FLOWERING PLANTS FOR THE UNHEATED GREENHOUSE
Spring
Anemone* Larkspur
Astilbe Lily-of-the-Valley
Carnation Narcissus*
Columbine Pansies
Crocus* Primrose
Cyclamen* Saxifraga
Daffodil* Scilla*
Forget-me-not Sedum
(Myosotis) Tulip*
Fritillaria* Viola
Hyacinth* Violet
Iris*
Summer
Begonia (Tuberous and Campanula
semperflorens) Canna*
Browallia Carnation
Calceolaria Celosia
(* Denotes plant usually grown from a bulb, corm, or tuber.)
Chrysanthemum Hibiscus
Crinum* Lobelia
Delphinium Oxalis *
Dutchman’s Pipe Petunia
(Aristolochia) Sedum
Flowering Tobacco Sweet Peas
(Nicotiana) Tigr idia *
Geranium Vallota*
(Pelargonium) Watsonia *
Autumn
Carnation Nerine*
Chrysanthemum Sternbergia*
Gladiolus* Sedum
Hosta* Sempervivum
Kniphofia* Zephryanthes
Lily*
Winter
Anemone* Iris alata9
Crocus* Jasmine
Cyclamen neapolitanum* Saxifraga
Erica Solanum
Fatsia Viburnum
Freesia* Violets
THE COOL GREENHOUSE
In the cool house the night temperature in winter should be about 55 to 60 degrees with the usual rise of 10 degrees during the day. In this temperature range, you can grow a variety of plants including all of those suggested for the unheated green house, as well as the plants in the following list, and your heating costs will be far less than those in a warm house of the same size.
FLOWERING PLANTS FOR THE COOL HOUSE
(Winter night temperature: 55-60 degrees.)
Spring
Aquilegia
(Columbine) Azalea Browallia
Camellia Carnation Cineraria Clematis
THE PRACTICAL GREENHOUSE FOR YOU
Clivia* Lachenalia*
Convallaria Lilium*
(Lily-of-the-V’alley) * Nasturtium
Freesia a (Tropaeolum)
Geranium Rhododendron
(Pelargonium) Summer
Achimenes* Clematis
Agapanthus* Morning Glory
Asarina (Convolvulus)
(Maurandia) Cup-and-Saucer Vine
Begonia (Cobea scandens)
(all types) Crinum *
Bougainvillea Datura
Cacti Fuchsia
(Some varieties) Habranthus0
Caladium* Hoya
Calceolaria Hydrangea
Campanula Impatiens
Canna* Lantana
Carnation
Autumn
Bignonia Mignonette
Browallia Nerine*
Chrysanthemum Salvia
Fatsia Streptocarpus
Flowering Maple Vallota*
(Abutilon)
Winter
Begonia Chrysanthemum
(Fibrous-rooted) Cineraria
Bouvardia Cyclamen*
Carnation Stocks Christmas Rose
(Helleborus Niger)
THE WARM HOUSE
The actual temperature range of a warm house is 60 to 70 degrees during winter nights. However, most of those who grow African violets, gloxinias, and so forth, as well as foliage plants of tropical origin and nature, find they get more rapid leaf growth and plant increase when the night temperature is 2 to 5 degrees higher than that range. The warm house is also used for growing many of the "stove" plants described in old garden encyclopedias and English gardening books.
(Winter night temperatures: 60-70 degrees.) Spring
Acacia Bromeliads
Aeschynanthus (various species)
(Trichosporum) Calceolaria
Amaryllis* Camellia
Arum* Carnation
Azalea Cineraria
Begonias Epiphyllum
(Tuberous,* semperflorens, Episcia
some rex) Freesia*
