Before planting it is a good idea to find your USDA Zone info to estimate 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 making a decision about when it's possible to plant erysimum is to consult the USDA zone info for Smithfield.

Planting Calendar for Erysimum

Frost tolerance for erysimum:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since erysimum are moderately cold tolerant you can plant them just a bit earlier in the year than other frost tender plants.

The earliest that you can plant erysimum in Smithfield 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 erysimum and expect a good harvest is probably September. If you wait any later than that and your erysimum may not have a chance to fully mature. If you are starting your erysimum indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Smithfield the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -15°F.

Since the USDA zone info for Smithfield 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 Smithfield you get a frost after April 15 be ready to cover your erysimum in the event of one of those late frosts.

USDA Zone Info for Smithfield

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Smithfield

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