The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

It's possible to estimate when it's a good idea to plant cosmos by looking at the USDA zone info for San Leandro.

Planting Calendar for Cosmos

Frost tolerance for cosmos:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Cosmos do ok in moderate cold which means that you can start planting them slightly earlier than other frost tender plants.

The earliest that you can plant cosmos in San Leandro 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 cosmos and expect a good harvest is probably September. Any later than that and your cosmos may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your cosmos indoors.

Last Frost Date

The average date of last frost is January 31 in San Leandro. You should expect an average low temperature of 30°F in the coldest months of winter.

It's important to remember that USDA zone info for San Leandro may not be accurate from year to year and the actual date of last frost will vary from year to year. Since half of the time in San Leandro last frost occurs after January 31 be ready to cover your cosmos in the event of a late frost.

USDA Zone Info for San Leandro

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in San Leandro

You may be interested in your other planting guides for San Leandro.