Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of getting a good idea when to plant onions is to consult the USDA zone info for Rockville.

Planting Calendar for Onions

Frost tolerance for onions:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

You can plant onions a lot earlier in the year because they do well in cold.

The earliest that you can plant onions in Rockville is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant onions and expect a good harvest is probably September. If you wait any later than that and your onions may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your onions indoors.

Last Frost Date

In Rockville the average date of last frost happens on April 15. It might get as low as 0°F during the coldest months of winter.

Since the USDA zone info for Rockville is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Rockville you get surprised by a frost after April 15 be ready to cover your onions if you have one of those late frosts.

USDA Zone Info for Rockville

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Rockville

You may be interested in your other planting guides for Rockville.