The USDA Zone info is a great tool for gardeners to help us determine 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.

A way of determining when it's possible to plant cardinal flower is to use the USDA zone info for San Juan.

Planting Calendar for Cardinal Flower

Frost tolerance for cardinal flower:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Since cardinal flower require warm weather you need to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant cardinal flower in San Juan is March. However, you really should wait until April if you don't want to take any chances.

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

Last Frost Date

In San Juan the average date of last frost happens on February 15. It might get as low as 25°F during the coldest months of winter.

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for San Juan and it changes from year to year. Half of the time in San Juan it frosts late in the year after February 15 so make sure that you are ready to protect your cardinal flower if you have a late frost.

USDA Zone Info for San Juan

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in San Juan

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