How to Grow Milk Thistle Inside
- 1). Fill a seed starting tray cell with seed starting medium. Do not use regular potting soil, which can harbor bacteria harmful to germinating seeds. Do this in the spring after the last frost.
- 2). Water the soil until it settles. Use the sharp end of a pencil to make a hole in the soil that is three times as deep as the milk thistle seed is wide. Drop the seed into the hole and firm the soil over the top of the seed.
- 3). Place the tray in a sunny, warm spot. Wait three weeks for the seed to germinate, keeping the soil moist to the touch the whole time. Once the seed germinates, you will see the stem break the soil. Reduce your watering to once a week and allow the plant to reach 3 inches in height.
- 4). Fill a regular plant pot with potting soil. Squeeze the bottom of the seed starting tray to loosen the soil. Turn the tray on its side and gently guide the plant out of the cell. You may need to wear gardening gloves, if the thistle stem is spiny.
- 5). Dig a hole in the potting soil with your hands that is as deep and wide as the root ball of the seedling. Lower the seedling into the hole and firm the soil around the base of the plant. Water the soil until the soil settles. Do not add any compost or fertilizer to the soil. Milk thistle does not need soil amendments to thrive.
- 6). Place the pot in a sunny window. Water the plant once a week. If you are using a long window planter, you can put more than one plant in the same container as long as they are at least 12 inches apart.
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