When to Plant Milk Thistle in Maine
Maine spans USDA hardiness 3b to 7a (zones 3b to 7a 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 3b · Zone 4a · Zone 4b · Zone 5a · Zone 5b · Zone 6a · Zone 6b · Zone 7a
Milk Thistle planting calendar for Maine, 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 Maine, 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 Maine, 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 Maine, 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) →
Milk Thistle planting calendar for Maine, 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 5b 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) →
Milk Thistle planting calendar for Maine, Zone 6a
Average last spring frost
April 25
Average first fall frost
October 10
Direct sow
May 9
Projected first harvest
Oct 6
Milk Thistle is ready to harvest in about 150 days. Full zone 6 guide (both 6a and 6b) →
Milk Thistle planting calendar for Maine, Zone 6b
Average last spring frost
April 20
Average first fall frost
October 15
Direct sow
May 4
Projected first harvest
Oct 1
Milk Thistle is ready to harvest in about 150 days. Full zone 6 guide (both 6a and 6b) →
Milk Thistle planting calendar for Maine, Zone 7a
Average last spring frost
April 15
Average first fall frost
October 20
Direct sow
Apr 29
Projected first harvest
Sep 26
Milk Thistle is ready to harvest in about 150 days. Full zone 7 guide (both 7a and 7b) →
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
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