One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Prosser can be used to determine when it's the best time to plant alyssum.

Planting Calendar for Alyssum

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

Alyssum do ok in pretty solid cold which tells us that you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant alyssum in Prosser 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 alyssum and expect a good harvest is probably September. Any later than that and your alyssum may not have a chance to really do well. Starting your alyssum indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Prosser. You should expect an average low temperature of 0°F in the coldest months of winter.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Prosser and it can change quite a bit from year to year. Half of the time in Prosser you get surprised by a frost after April 15 so always be ready to protect your alyssum in the event of one of those late frosts.

USDA Zone Info for Prosser

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 Prosser

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