When to Plant Milk Thistle in Minnesota
Minnesota spans USDA hardiness 3a to 5a (zones 3a to 5a on this page). Plant milk thistle by your local frost date, not the calendar — pick your zone below for exact start-indoors, transplant, and harvest dates.
Jump to: Zone 3a · Zone 3b · Zone 4a · Zone 4b · Zone 5a
Milk Thistle planting calendar for Minnesota, Zone 3a
Average last spring frost
May 30
Average first fall frost
September 10
Direct sow
Jun 13
Milk Thistle needs about 150 days to mature — longer than Zone 3a typically stays frost-free, so it likely won't reliably ripen there outdoors without a head start indoors or season extension. Full zone 3 guide (both 3a and 3b) →
Milk Thistle planting calendar for Minnesota, Zone 3b
Average last spring frost
May 20
Average first fall frost
September 15
Direct sow
Jun 3
Milk Thistle needs about 150 days to mature — longer than Zone 3b typically stays frost-free, so it likely won't reliably ripen there outdoors without a head start indoors or season extension. Full zone 3 guide (both 3a and 3b) →
Milk Thistle planting calendar for Minnesota, Zone 4a
Average last spring frost
May 15
Average first fall frost
September 20
Direct sow
May 29
Milk Thistle needs about 150 days to mature — longer than Zone 4a typically stays frost-free, so it likely won't reliably ripen there outdoors without a head start indoors or season extension. Full zone 4 guide (both 4a and 4b) →
Milk Thistle planting calendar for Minnesota, Zone 4b
Average last spring frost
May 10
Average first fall frost
September 25
Direct sow
May 24
Milk Thistle needs about 150 days to mature — longer than Zone 4b typically stays frost-free, so it likely won't reliably ripen there outdoors without a head start indoors or season extension. Full zone 4 guide (both 4a and 4b) →
Milk Thistle planting calendar for Minnesota, 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 5a typically stays frost-free, so it likely won't reliably ripen there outdoors without a head start indoors or season extension. Full zone 5 guide (both 5a and 5b) →
Not sure which half-zone you're in? 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
🌱 Grow milk thistle with a calendar built for your exact yard
HomeSown turns your ZIP code into a personalized planting calendar, watering reminders, and pest help. Free to start.
Start your free garden →