Temperatures are expected to drop into the 30s in the heat sink of D.C. proper Friday night into Saturday morning, and Saturday night into Sunday morning. Outlying areas are looking at low 30s with a serious risk of frost and possibly a hard freeze.
But many gardeners have jumped the gun and already have summer plants, such as tomatoes and peppers, in the ground. You can try and protect these plants by placing upside-down cardboard boxes over them before sunset Friday. Place a rock or a brick on top to keep the boxes in place.
Do not remove the boxes Saturday, as even the daytime temperatures will be injurious to frost-tender plants in many areas.
Remove the boxes after noon Sunday, but keep them handy, as cold overnight temperatures are predicted again later in the week.
An alternative is to cover the plants with a professional row cover such as Reemay or sheer curtains, but it will be important to anchor the covers securely as Saturday is predicted to be extremely windy.
Do not use tarps or sheets of plastic; they have a strong potential of doing more harm than good.
If you have frost-tender plants that are not yet in the ground, keep them inside until the 10-day forecast shows nights at least in the high 40s, preferably 50 degrees or more.
Mike McGrath was editor-in-chief of ORGANIC GARDENING magazine from 1990 through 1997. He has been the host of the nationally syndicated public radio show “You Bet Your Garden” since 1998 and WTOP Garden Editor since 1999. Send him your garden or pest control questions at MikeMcG@PTD.net.