Freezing Forecast Could Affect Reston Plants Overnight

The National Weather Service has issued a Freeze Warning for Fairfax County and surrounding areas for late Tuesday night and early Wednesday.

Overnight temperatures are expected to dip to about 30 degrees, which will kill your cold-sensitive plants if you have already (optimistically?) planted them. Traditionally, the area’s last frost is between April 21-30, according to gardening zone maps.

If you have garden containers, bring them inside where it is warmer. If plants are in the ground, follow these tips from The Garden Helper:

• Water the garden thoroughly before nightfall. The soil will release moisture into the air around your plants during the night, keeping the air somewhat warmer.
• Cover up. By the time it gets dark much of the stored heat in the garden has already been lost. If you have time, build a simple frame around the plant, or row of plants. (Even a single stake can be used in many cases.) Then drape a cover of newspaper, cardboard, plastic tarps, bed sheeting or any other lightweight material over the frame to create a tent. If you don’t have time to create a frame, lay the protective cover directly onto the plant. This will help to slow the loss of heat rising from the foliage and the ground. Remove the covers in the morning, once the frost has thawed, to let the light and fresh air back in, and to prevent overheating by the sun.
• For smaller individual plants you can use glass jars, milk jugs with the bottom removed, paper cups upside down flower pots as heat traps. Don’t forget to remove these covers in the morning.
• You can collect heat during the day by painting plastic milk jugs black and filling them with water. Place them around your plants where they will collect heat during the day. Water loses heat more slowly than either soil or air. This collected heat will radiate out throughout the night.