When to Plant Leeks in Alton, IL

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.

By reviewing the USDA zone info for Alton you will be able to determine when to plant leeks.


Planting Calendar for Leeks

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

Since leeks are very cold tolerant you can plant them quite a bit earlier in the year than more sensitive plants.

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

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

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Alton. It might get as low as -10°F during the coldest months of winter.

Always keep in mind that USDA zone info for Alton is not always accurate and the actual date of last frost can change quite a bit from year to year. Since half of the time in Alton you get a frost after April 15 be ready to protect your leeks in the event of one of those late frosts.

USDA Zone Info for Alton

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 Alton

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