Permanent Raised Bed Gardening: Overcoming Weather Woes

Top, heavyweight floating cover used for frost protection; bottom, floating cover removed from flowering cantaloupe

Yields of wind-pollinated crops such as tomato, pepper and eggplant can be reduced if covers are left on too long. Temperature under the covers should not exceed 90°F for more than a few hours during the flowering stage. For crops requiring bee pollination such as squash, cucumbers and melon, the covers should be removed when female flowers appear.

Row covers not only enhance crop development but also hasten weed growth. Because of the impracticality of weeding under crop covers, you should use plastic mulch as well. You can't beat this combination for maximum crop growth and weed control.

If you're interested in taking crop protection to the next level, consider constructing a hoop house, whose primary advantage is convenience. You don't have to remove a cover to gain access to your plants; you simply walk in!

Hoop houses are generally Quonset-shaped structures constructed of metal or plastic hoops. They are covered with a single layer of 6-mil greenhouse-grade polyethylene film and are vented by rolling up the sides. There is no permanent heating system, and there are no electrical connections. The ends of the houses are framed and covered with poly film or other transparent materials. You can place a door in the end walls or make them completely detachable, permitting better access. Compared to greenhouses, hoop houses are relatively inexpensive at $1.50 to $3.00 per square foot.

Hoop house temperature management is difficult because the size of the house, film transparency, cloud cover and wind speed affect heat gain or loss. As a rule, houses should be vented before the internal air temperature reaches 90°F. The amount of venting depends on the wind speed, the ambient temperature and the desired growing temperature (80° to 85°F for bell pepper, snap bean and tomato; 90°F for cucurbits, eggplant, hot pepper, southern pea and okra), which can be maintained by side vent adjustments.