From an article by Marisa Y. Thompson, Ph.D., Extension Horticulture Specialist at New Mexico State University

How can I protect my backyard peach tree from losing fruit to late frosts?

This is a tough one. There’s lots of advice out there for things that might help (emphasis on the “might”). Your options for protecting those precious buds and flowers really depend so much on how old and big the tree is, what stage of development the buds are in, how cold it’s going to get, how high wind speeds get, and how long the cold lasts. Because eastern parts of the state might get a cold snap this week, I’m focusing on what to do to protect existing trees in your yard from late frosts.

There are some tried and true tricks for maximizing fruit load by protecting flower buds, open flowers, and developing fruit from freezing temperatures. Covering your tree in some way is likely the best option. This is just one reason selecting trees with dwarf rootstocks is recommended. If the tree is small enough, you can cover it with a pop-up tent like those used at farmers’ markets. Just trapping the warm air under that umbrella can keep temperatures more moderate underneath.  Depending on how cold it’s going to get, adding an incandescent light bulb can bump the temperature up several degrees into the safety zone nearer freezing temperatures. Safety is key! Do not use heaters or anything with a flame that might catch fire. Depending on how high winds are expected to get, that canopy cover might not work because the warm air won’t be trapped as well.

If you expect high winds, don’t have a pop-up tent, or your tree won’t fit underneath it but it’s small enough to cover with a sheet or blanket, this is a good option. Wrapping the tree canopy without knocking off some of the flowers is impossible. The struggle is real. Ask a friend to help and take deep breaths. Avoid plastic tarp as a cover if it will be in direct contact with the buds because plastic isn’t a good insulator, and tissues touching the plastic may still get very cold. Whichever cover you use, be sure to uncover the tree again during the day.

Another idea is watering the root zone a day before the cold sets in so the ground below can hold more heat and keep that microclimate warmer. If there’s enough sun and enough time, painting a 5-gallon (or larger) water container black and allowing it to heat up in full sun during the day, then leaving it at the base of the tree where it can release heat slowly overnight can help. If there’s not enough time, use pre-heated water in the container. However, again, if temperatures drop very low or wind speeds get high, these techniques won’t work at keeping the warm air near the buds where you need it most. High winds over wet soil may even act like a swamp cooler and lower temperatures even further.

Some gardeners recommend stringing holiday lights around the canopy to help keep buds warm, and this might help, but not with LED lights. Buds that are near (but not touching) a bulb can benefit from the warmth. The trouble for me with this tip is that I feel certain I’d knock off all the flowers when stringing the lights.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.