Update: Cold temperatures are predicted for the nights of May 5-8. There is a potential for frost and record cold temperatures on the night of Saturday, May 9.
At this point in the spring a lot of people ask whether it is safe to place plants outside. Here’s what you need to know:
- Most tropical and annual plants can be killed or damaged by frost or near-freezing temperatures.
- The risk of frost is high until early May. While the risk of frost after May 10 is low, temperatures low enough to cause damage can occur any time during the month of May. Memorial Day at the end of May is the point when there is no longer any danger of frost.
- If you choose to put cold-sensitive plants outside in April or May, we strongly encourage you to monitor weather forecasts carefully.
- Whenever temperatures below 40 degrees are predicted, be prepared to bring sensitive plants inside. Covering plants with a bed sheet can provide some protection but is not guaranteed.
Cold-tolerant plants are safe to put outside now regardless of the temperature. These include:
- Many perennials
- Cold-tolerant herbs such as parsley, sage, thyme, and oregano (but not basil!)
- Cold-tolerant vegetables such as lettuce, broccoli, cauliflower, and Brussels sprouts
- All hardy shrubs and trees
After many decades of working in this business, we’ve learned the hard way not to push the envelope. If you have any questions about what is safe to plant outside, please ask us.