Planning and Building a Greenhouse
Summer can turn your greenhouse into an oven unless you are aware of a few precautionary measures which will insure the vigor of your favorite plants. One solution is to remove any heat-sensitive plants from the greenhouse and locate them in your home or the coolest spot in your landscape. Also check the ventilation of your greenhouse. The more air circulation that you can provide, the better off your plants will be. Most home greenhouses are not equipped for cooling purposes, so open any doors and vents and if you have any removable portions of your greenhouse, take them off. If you do have a cooling system, be sure it is operating at peak efficiency.
Adequate shading is of prime importance, whether it be shade cloth, white wash or cheese cloth. Dark shade cloths will cool your greenhouse more efficiently if they are on the outside of the structure, since dark objects absorb heat. Also, by being on the outside, these materials will reduce the sunlight passing through your greenhouse covering.
Cultural tips
The higher temperatures in your greenhouse at this time of year can also be to your advantage. It is also the best time to propagate cuttings of warm season plants. These include copper plants, crotons, hibiscus, shrimp plants, lantanas and many tropical foliage plants. These plants are normally very difficult to root after they have been subjected to temperatures in the high 50s to low 60s. You can wait for cooler weather to propagate coleus, impatiens and begonias. If you plan to grow your own winter and spring annuals, this month will probably be the last time you can order seeds (such as alyssum, bachelor’s button, calendula, delphinium, petunias, pansies and stock) and still get them on time. Be aware of spider mites and mealy bugs and keep your plants treated. The reproductive rate of these pests is fantastically high when temperatures are high.
Unusual plants
The elephant’s ear has two interesting variations that many local gardeners have not seen. The first is the black elephant’s ear, Colocasia affinis jenningsi. This member of the aroid family is a striking plant with elephant-ear-like leaves which are dark purple with green edges. Leaf size is slightly larger than most caladium leaves.
As with most members of this plant group, adequate moisture is important. In fact, it will tolerate and even thrive in very wet situations. Best growth occurs in a highly organic soil. To maintain best foliage color, at least a half-day of sunshine is necessary.
Propagation is best effected by dividing the plants as new leaves appear in the spring. The black elephant’s ear is root hardy most winters, especially if well mulched with leaves. If enough moisture is provided, this plant is also adaptable to container growing.
Another attractive variation is the variegated upright elephant’s ear, or Alocasia macrorhiza variegata. It requires basically the same culture as the black elephant’s ear in terms of soil and moisture, but differs in light and temperature tolerances. The variegated upright elephant’s ear requires mostly shade, with some morning sun tolerated. It is not reliably winter hardy and therefore should be dug up each fall or grown in a container.
Spider mites and mealy bugs can also be a problem with this variety of elephant’s ear, especially if it is grown indoors. Most sprays will control them.
