When to Plant Lobelia in Swarthmore, PA

One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By checking out the USDA zone info for Swarthmore it's a good idea to determine when it's a good idea to plant lobelia.


Planting Calendar for Lobelia

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

Lobelia tend to make it in a bit of cold which tells us that you can plant them a lot earlier in the year than other plants that might not handle the cold.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant lobelia
Possibly ok, but a risky time to plant lobelia
Probably not a good time to plant lobelia

The earliest that you can plant lobelia in Swarthmore 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 lobelia and expect a good harvest is probably September. You probably don't want to wait any later than that or else your lobelia may not have a chance to fully mature. You can get started a few weeks earlier by starting your lobelia indoors.

Last Frost Date

In Swarthmore the average date of last frost happens on April 15. You should expect an average low temperature of 0°F in the coldest months of winter.

Remember that USDA zone info for Swarthmore is an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Swarthmore it frosts late in the year after April 15 so make sure that you are ready to cover your lobelia if you have one of those late frosts.

USDA Zone Info for Swarthmore

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 Low0°F
Highest Expected Low5°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 Swarthmore

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