Milk Thistle
Seed # 18
Basic Information
- Seed Number
- 18
- Seed Name
- Milk Thistle
- Variety
- Not recorded
- Category
- Medicinal
- Plant Family
- Asteraceae
- Plant Type
- Milk thistle (Silybum marianum)
- Planting Method
- Direct Sow
- Seed Status
- In Seed Bank
- Created
- 2026-08-14 00:50:34
- Updated
- 2026-08-19 15:35:29
Planting Information
- Start Planting Date
- Mar 15
- Last Recommended Planting Date
- May 15
- Plantable Months
- March, April, May
- Indoor Start
- Not recorded
- Direct Sow
- Mar 15 – May 15
- Transplant
- Not Recommended
- Indoor Start Weeks Before Frost
- Not Recommended
- Transplant Weeks After Frost
- Not Recommended
- Germination Days
- 10–21 days
- Harvest/Maturity
- Not recorded
- Succession Planting
- Not recorded
Growing Conditions
- Ideal Soil Temperature
- 55-70°F
- Planting Depth
- 1/4 in
- Plant Spacing
- 24-36 in
- Row Spacing
- 36 in
- Thin-To Spacing
- 24-36 in
- Sun Requirements
- Full sun
- Water Needs
- Moderate water while establishing; tolerates dry conditions once established
- Soil Preference
- Well-drained soil; tolerates poor and disturbed soils
- Minimum Container Size
- 10 gal
- Plant Height
- 3-6 ft
- Perennial/Biennial Status
- Biennial
- Container Friendly
- Yes
- Trellis/Support Needed
- No
- Frost Tolerant
- Yes
- Heat Tolerant
- Yes
- Drought Tolerant
- Yes
- Pollinator Friendly
- Yes
- Medicinal
- Yes
Garden Uses
Container Medicinal Pollinator Seed SavingCompanion Planting
| Plant | Relationship | Notes |
|---|---|---|
| Basil | Good Companion | Not recorded |
| Basil | Good Companion | Not recorded |
| Basil | Good Companion | Not recorded |
| Calendula | Good Companion | Not recorded |
| Calendula | Good Companion | Not recorded |
| Chamomile | Good Companion | Not recorded |
| Dill | Good Companion | Not recorded |
Storage
- Seed Source/Brand
- MSU Extension; Detroit frost dates; Almanac Detroit
- Packet Year
- Not recorded
- Quantity Notes
- Not recorded
- Purchase Date
- Not recorded
- Expiration Year
- Not recorded
- Storage Box
- Not recorded
- Container
- Not recorded
- Envelope
- Not recorded
- Row
- Not recorded
- Slot
- Not recorded
- Storage Notes
- Not recorded
Notes
Original Planting Method: Direct sow or start indoors
Outdoor / Direct Sow / Transplant Window: May 1 – Jul 1
Days to Harvest / Bloom: 60–100 days
Succession / Reusable Notes: Good for annual herb beds and pollinator strips.
Zone 6B Notes: Harvest flowers/leaves regularly depending on crop.
Companion Plants: Vegetables, calendula, chamomile, basil, dill, pollinator flowers
Avoid Planting Near / Watch Outs: Overcrowding
Sources: MSU Extension: https://www.canr.msu.edu/resources/garden_planning_calendar | Detroit frost dates: https://www.ufseeds.com/vegetable-planting-calendar-detroit-michigan.html | Almanac Detroit: https://www.almanac.com/gardening/planting-calendar/MI/Detroit
[[RESEARCH ENRICHMENT START]]
Zone 6B: Can behave as a biennial and self-seed aggressively. Prevent unwanted seed dispersal.
Germination: Direct sow shallowly in cool spring soil.
Harvest: For seed, harvest mature flower heads before seeds disperse. Handle spiny plants with gloves.
Seed Saving: Allow selected heads to mature, then bag before seeds disperse. Dry thoroughly before storage.
Special Care: Spiny and potentially weedy; site away from paths and control seed spread.
Research Source: Missouri Botanical Garden — https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=277472 — Silybum marianum identity and biennial growth habit
Research Source: NCCIH — https://www.nccih.nih.gov/health/milk-thistle — established herbal and medicinal use of milk thistle
[[RESEARCH ENRICHMENT END]]