When to Plant Milk Thistle in Zone 5
In USDA zone 5a, plant outdoors May 19 to October 1. (5a shown here — see 5a and 5b dates separately below.)
Milk Thistle planting calendar for USDA Zone 5a
Average last spring frost
May 5
Average first fall frost
October 1
Direct sow
May 19
Milk Thistle needs about 150 days to mature — longer than zone 5atypically stays frost-free, so it likely won't reliably ripen there outdoors without a head start indoors or season extension.
Milk Thistle planting calendar for USDA Zone 5b
Average last spring frost
April 30
Average first fall frost
October 5
Direct sow
May 14
Milk Thistle needs about 150 days to mature — longer than zone 5btypically stays frost-free, so it likely won't reliably ripen there outdoors without a head start indoors or season extension.
Not sure whether you're in 5a or 5b? Set your ZIP in HomeSown for dates tuned to your exact location.
Varieties to grow
1 variety of milk thistle in the HomeSown library. Tap any for its full grow guide.
Common problems with milk thistle
What to watch for, with identification and treatment for each
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