Suppose you have a new greenhouse and are wondering what to do to kill it with color. You have already looked through some catalogs, only to learn that many of the things you would like should have been started way back last June.
November is late for many plants, but many flowering kinds can still grow during the present winter and on into spring.
Three standard temperature ranges for greenhouses have been set up to suit the needs of plants.
These are based on the night temperature, which is the critical time of the 24 hours. Certain plants will not bloom if the night temperature is 60° degrees Fahrenheit, but a flower with nights at 50° degrees Fahrenheit.
The night temperature should vary as little as possible because fluctuation causes poor or erratic flowering.
A variation of a few degrees will occur as the thermostat turns the heat on and off, but the variation should be kept as narrow as possible. Day temperatures should be 10 degrees higher.
The three temperature ranges generally used are “cool,” with nights of 50° degrees Fahrenheit; “intermediate,” with nights of 55° to 60° degrees Fahrenheit; and “warm,” with nights of 60° to 65° degrees Fahrenheit.
Within each range, a wide variety of compatible plants can be grown. Choose kinds that have the same temperature requirements.
Start With Cool House
We suggest that you start with the 50° degrees Fahrenheit greenhouse because it is easy to manage, and you can have plants that will give a colorful show in a short time.
Tulips, hyacinths, grape hyacinths, and narcissus can be brought into flower in a cool house during late winter.
Plant the bulbs in pots and store them in a cool, dark place for about three months to allow them to make roots and develop the flowering shoot before bringing them into the greenhouse.
A storage room, where the temperature stays between 40° to 50° degrees Fahrenheit, is satisfactory.
Bulb Planting and Storage
In other years, when you can get an earlier start, bulbs may be planted in late September, and certain varieties can be brought into bloom in December, making attractive Christmas presents.
Since you will be starting a month or so late, let them stay in the storage room until early February.
A mixture of three parts loam to one of peat, plus a little superphosphate, is satisfactory for bulbs and most other plants we will discuss.
For showy groups of flowers, use 7 or 8-inch azalea pots (three-quarters the height of standard pots).
This size will accommodate six or seven tulips, three or four narcissus, three hyacinths, and a large number of grape hyacinths. After potting, water well. When in storage, water only occasionally.
Forcing Bulbs and Flower Varieties
Early in February, start bringing in the pots, all at once if you wish, or at weekly intervals to have a sequence of flowers.
Put the pots under the bench, where the temperature is intermediate between the storage room and the bench, and the light is subdued until the shoots begin rapid growth. Then, set them on the bench.
Tulips
- Albino
- Bartigon
- Golden Harvest
- Red Pitt
- Rose Copland
- Utopia
- William Copeland
- William Pitt
Hyacinths
- Bismarck
- City of Haarlem
- Jan Bos
- King of the Blues
- Ostara
- Marconi
- Pink Pearl
Narcissus
- King Alfred
- Aerolite
- Rembrandt (trumpet narcissus)
- Actaea
- Poetaz hybrids (white or yellow petals and small bright trumpets)
- Grape hyacinths can also be forced for touches of blue and white
Greenhouse iris, Wedgewood (blue), Imperator (deep blue), White Excelsior, and Yellow Queen, choice subjects for winter or early spring, may be planted now directly on the bench or in flats. Keep them well-watered. They will flower in eight to 10 weeks.
The Victoria hybrids of ranunculus (Ranunculus asiaticus) are striking flowers with a wide color range.
Plant the little tubers 2″ inches deep, with the “claws’ down, in a mixture of four parts sandy loam to one of Ieafmold or I manure. They will flower in March.
Geraniums Are Exciting
Geraniums are a world in themselves. Growers have built up exciting collections among the hundreds of varieties.
Geraniums belong to the genus Pelargonium, but there are distinct groups known as zonal, scented-leaved, ivy-leaved, and show pelargoniums (also called Martha Washington).
Among the zones are some with variegated leaves and charming miniature types. All do best in the 50° degrees Fahrenheit house.
Geranium Cuttings
Geranium cuttings may be taken or purchased during fall, winter, and spring and rooted in sand or vermiculite. Water them thoroughly at once.
Rig up a little extra shade and keep them damp until they are well-rooted. Then, pot in four-inch containers in a mixture of three parts soil, one part leaf mold, and a little superphosphate.
For winter bloom, keep them in small 1 pots, as slightly pot-bound plants flower more readily.
There are many plants to grow from seed. A spring crop can be produced from November showings of calendula, candytuft, snapdragon, baby’s breath, salpiglossis, schizanthus, and sweet peas.
Plant the seed in flats and transplant it when needed. Or you can sow it directly on the bench and thin seedlings.
44659 by Rebecca T. Northen