Two worthwhile ideas come to mind for making the most of summer in the small greenhouse. These are useful crops or tropical displays.
Permanent flowering plants, especially those which are winter-blooming in the cool or moderately warm greenhouse, need 2 months or more outdoors and may be plunged into the ground in a protected place.
Annuals grown in the benches for spring bloom have run their course by June.
In many cases, shelves are bare, and benches are free of a complete change of scene during the warm months.
Raise Plants That Respond To Warmth And Humidity
If you choose to raise fruits, vegetables or herbs, grow only those that respond to warmth and humidity. All varieties of peppers, parsley, and okra fall into this category.
A bench of dwarf lima beans will give a larger and more succulent yield than those grown outdoors in most sections. Most satisfactory of all, however, is the vine crops.
One tomato vine, pruned to a single leader and trained up a side wall, will grow to prodigious size, producing a wealth of tender fruit.
Cucumbers, melons, zucchini squash, or even the new small-fruited watermelon might be chosen.
Posy Bean
Pole beans offer another possibility. For example, a climber is known in some rural areas as the “posy bean,” which is both decorative and edible.
It is usually sold as a scarlet runner (Phaseolus coccineus). It’s grown largely for ornament because of its bright green foliage and many red flowers, and the pods are delicious when picked young and cooked like string beans.
The seeds are a beautiful mottled lavender, and they also can be used as shell beans when mature.
If you prefer to continue with purely decorative material during the summer, there is a plentiful and varied choice.
A Tropical Atmosphere For Greenhouses
If a greenhouse is run at a cool temperature for the rest of the year, it is unnecessary to go to the expense of costly exotic plants to provide a tropical atmosphere in July and August.
Common Summer Flowers
Many common summer flowers are native to the tropics. When their native conditions are duplicated in the way of humidity and warmth, most of them respond dramatically under glass.
Petunia comes from Argentine, salpiglossis, and schizanthus from Chile, and ageratum, hunnemannia, and leptosyne from Mexico. Buy seeds of these well-named varieties.
These flowers bloom so spectacularly in the summer greenhouse that they scarcely seem related to the same kinds grown out of doors.
Tender Annuals
Godetia, nigella, nicotiana, and indeed almost any of the tender annuals may be added to the list.
No matter how satisfactory common flowers may be in the warm greenhouse, some people associate the idea of a tropical display with the unfamiliar and the exotic.
With its curious flowers and attractive pest-free foliage, a passion vine might fill this requirement.
Cathedral Bells
Cathedral bells (Cobaea scandens) will bloom profusely, each bell first green, then lavender, and finally developing into a curiously-shaped and decorative seed pod.
By August, both flowers and seed pods in profusion hang down from a vine that has been trained up and across the rafters.
Dalura Meld
For the bench, nothing could be more exotic than Dalura meld. It must have room.
Three or four plants will cover a small bench with large dark green leaves from which rise the huge white angel’s trumpets, sometimes 12” inches long.
These flowers have a faint musky fragrance. They last only a day, but once a plant is established, they appear over a long period.
Bulbs For Summer Greenhouse
Bulbs provide another excellent choice for the summer greenhouse. Tuberous begonias, gloxinias, dwarf dahlias, and miniature gladiolus all do better under glass than in the garden.
Most summer flowering bulbous plants are worth a try. Members of the amaryllis family that are especially successful include hemerocallis, Haemanthus, pancratium, and Anthericum.
Climbing Lily “Gloriosa”
The climbing lily or gloriosa gives us a bulbous plant in the vine category, although its height is not likely to exceed 4’ feet with me.
Deciding what to grow, shading, watering, and spraying for pests are the three secrets of success in the summer greenhouse.
With attention to these three chores, plants that are given proper soil will otherwise take care of themselves.
Necessary Shading
Shading is accomplished by movable, slatted screens or by whitewash applied directly to the glass. Light shade may be necessary as early as April.
By June, the screens should remain in place for a longer period during the middle of a sunny day. Or, apply another coat of whitewash or some similar material.
Using Glass Wax
I have had success with the window cleaner known as glass wax. This can be applied on the inside with a sponge mop. One coat in April, another in June, suffice for the summer.
To be sure, it takes a certain amount of hard rubbing with ammonia or a fine abrasive to remove glass wax in the fall after it has baked on the glass all summer.
Nevertheless, the advantages of its neat appearance and the ease with which it can be applied count in its favor. Shading is also accomplished in some measure by vines.
Whereas at other times of the year, care must be taken to keep vines away from the glass, they may be allowed to climb on supports up the sides of the greenhouse in the summer.
Daily Watering
Watering is a daily necessity except perhaps when it rains heavily. However, on sunny days, it may be advantageous to water twice or even three times.
No matter the shading, the sun’s heat will dry out the benches and evaporate the moisture in the air, sometimes in a few short hours.
General rules for watering are held in the summer as well as the winter. Some plants may even like to dry out almost before watering again.
Importance of Humidity
Humidity is almost more important than the actual moisture at the plant’s roots.
The best way to keep the humidity high is to water down the whole house — glass, rafters, duckboards, and the areas under the benches.
This should be done with the hose’s nozzle set at a fine spray. Care must be taken, however, not to water-log the soil in which plants are growing.
On the other hand, it is practically impossible to have the air become too humid if it is hot and dry out of doors.
An important function of high humidity is to keep the temperature down during the day.
If the air becomes dry, the thermometer can quickly run up over a hundred in the summer greenhouse, even though it registers no more than 70° degrees Fahrenheit outside.
How To Combat Harmful Insects In A Warm House
Harmful insects not only breed more rapidly in a warm house than in a cool one, but during the summer, they find their way in from the outdoors.
The best way to combat them is to follow a regular weekly spraying schedule, whether there are signs of trouble or not. The under and the upper sides of foliage should be reached.
The general-purpose “bug bombs” on sale today greatly reduce the time and energy needed to carry out such a program and include mixtures for different kinds of pests.
Fungus diseases caused by dampness are more difficult to cope with, but luckily, plant material for a warm house is generally fairly immune.
Bulbous plants should be dusted with a disinfectant before they are started to grow as a precautionary measure.
At the first sign of mildew or rust, dust with powdered sulfur and discard badly affected plants.
Best Method For The Passion Vine
Except for bulbous kinds, all the plants mentioned can be raised from seed sown in March or April.
A few, such as datura and the passion vine, can be propagated by cuttings of new growth once they are established.
This is the best method for the passion vine since occasionally, plants from seed will not flower.
Spring Greenhouse
In general, however, all that is needed is space in the spring greenhouse to keep the desired seedlings coming along in the sun.
In most cases, bulbs bought for summer use can be saved for a second season.
44659 by Marion Dulles