When to Plant Tree onions in Charleston, IL

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 looking at the USDA zone info for Charleston you will be able to figure out when it's the best time to plant tree onions.

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Planting Calendar for Tree onions

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

You can plant tree onions slightly earlier in the year because they do ok in moderate cold.

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

The earliest that you can plant tree onions in Charleston 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 tree onions and expect a good harvest is probably August. You probably don't want to wait any later than that or else your tree onions may not have a chance to grow to maturity. Starting your tree onions indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Charleston the average date of last frost happens on April 15. It might get as low as -10°F during the coldest months of winter.

Always keep in mind that USDA zone info for Charleston is an average and the actual date of last frost is different every year. Half of the time in Charleston it frosts late in the year after April 15 so make sure that you are prepared to protect your tree onions if you have a surprise late frost.

USDA Zone Info for Charleston

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)April 15
Average Date of First Frost (fall)October 15
Lowest Expected Low-10°F
Highest Expected Low-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Charleston

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