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Pruning guide · Herbaceous plant
Milk thistle: when and how to prune
Silybum marianum
Milk thistle is best pruned in August–September.
| Pruning months | August–September |
|---|---|
| Flowering | June–August |
| Native to Belgium | No, planted |
Milk thistle: when to prune it?
After flowering, in August–September; real pruning is not needed.
Milk thistle: how to prune it?
- Cut off faded heads as soon as the fluff appears if you do not want seedlings.
- Leave a few heads for the goldfinches and to collect your own seed.
- Once the plant has died, cut it off at the base; the taproot can rot down in the ground.
How much to cut, and how often?
- One pruning period a year: August–September.
What does it mean for wildlife?
- Don’t cut more than you need to: what stays standing gives insects and birds food and shelter.
Caution: Wear sturdy gloves and long sleeves: the spines go straight through thin fabric.
Nearby: related pruning guides
Plant profile: Milk thistle · Pruning calendar and basic rules
This guide is compiled from the Bladwijzer plant profile and pruning calendar.