Dear Friends of San Francisco Botanical Garden,
As you've probably heard, we're in for some cold weather....staff and volunteers have been busy getting frost cloth over everything that needs it and moving as many of our nursery plants as possible up the hill toward the Children's Garden, where it will be a little warmer.
If you have outdoor plants like us, you should probably prepare them for the cold. Here are some basic steps to take before a potential frost and after:
Cover tender plants with frost cloth. Hopefully it hasn't sold out everywhere at this point. Check your local nursery or garden supply store for availability.Using an old sheet is better than nothing, but frost cloth is preferable.
Most plants could benefit from a small watering as part of your preparation, but NOT cactus and other water-retaining succulents. As you know, water expands when it freezes.If the cells of your succulents are full of water, they will burst when the water freezes, killing the plant.If they're a little low on water when the cold arrives, there's a chance the cell walls will be able to stand a little expansion and won't burst.
Bring as many of your container plants inside as possible. If they don't fit inside, placing them against an outside wall of your house or apartment, particularly if there's an overhang, can make a big difference.
What do you do after a freeze? Be patient.The cold spell in 1989 was tough on our plants here at the garden, but more made it through than we originally thought.The initial survey after the freeze showed us that 80% of the plants in our Cloud Forest Garden had died.Yet the roots of many of these plants survived, and in the spring, it looked like actually only 40% had died in the big freeze.By summer, the number went down to 20%.We still lost some great plants, but not nearly as many as it looked right after the freeze.
Do not prune or cut back plants too hastily. In case of another cold spell, an unpruned plant helps provide insulation for its roots and main trunk.
Pruning now could force the plant into growth, which would stress the plant and force it to use of more of its reserves, leaving it vulnerable to another cold spell.
Wait for possible new growth on woody plants to actually know what's dead.
Water only if dry.If roots are damaged, over-watering now can encourage root injury.
Mulches moderate root temperatures and preserve moisture.
It may take several months for new growth to appear.
Consider keeping notes on the damage that occurred for your own reference.
Sincerely,
Don Mahoney
Horticultural Manager
San Francisco Botanical Garden Society
