Tree Freeze Alert: Palo Alto Area
Thank you to our friends at Mountain View Trees for alerting us to the weekend weather, and providing this important information. Freezing temperatures are projected tomorrow and through the weekend. A cold air mass will spread across our entire area bringing new lows in to the 20s and lower 30s. It will be cold enough to freeze your trees' buds/blossoms, fruit, leaves, and/or twigs.
Most susceptible trees include:
Citrus, Jacaranda, Catalpa, Oleander, Eugenia, and other tropical/sub-tropical plants are most likely to sustain damage. Tender, new growth is also easily injured by freezing temperatures.
What can you do?
Protect your trees.
Cover plants with burlap, sheets, tarps, etc. that extend to the ground to trap in the earth's accumulated warmth. Use a frame or stakes to minimize contact between the cover and the foliage. Also, bring potted plants and trees to more protected locations.
Keep plants well-watered.
- Moist soil will absorb more solar radiation than dry soil and will re-radiate heat during the night.
- If you have a large tree that needs protection, running sprinklers at the coldest time of the night (usually between 4 and 6 a.m.) can give it a slight edge. The strategy makes use of latent heat released when water changes from liquid to a solid.
- When ice crystals form on the leaf surface they draw moisture from the leaf tissue. The damage from this dehydration will be less severe if the plant is not already drought-stressed.
- Remove turf/weeds from under trees' canopies - bare soil absorbs and reflects heat best.
- Wood chip mulch prevents soil moisture loss and insulates roots.
- Plant frost-sensitive plants near sources of reflective heat (like buildings, walls, etc).
After the frost, help trees recover.
- Do not prune anything off immediately. Wait to see what sprouts in the spring; the damage is often not nearly as bad as it initially looks, and new growth may come out of tissue that you thought was dead.
- If dieback is severe enough and your tree has lost "shade," protect the now-unshaded portions of the trunk/branches from the sun with a physical cover or with whitewash (1:1 ratio of latex paint and water).
- Remove frosted/mushy fruit while still salvageable for snacking on or juicing.
- Wait to fertilize (if necessary) until the cold weather has passed. There is no evidence to indicate that frozen trees respond to any special fertilizer that is meant to stimulate growth.
Mountain View Trees is fiscally sponsored by Canopy.
For more information, or to ask questions to an arborist, please join us at any upcoming event or visit Canopy.org and click Contact Us.