Horehound (Marrubium vulgare).

Horehound (Marrubium vulgare) is a perennial herb that is commonly used for its medicinal properties, particularly in cough and cold remedies. It is a hardy plant that grows well in most soils and is drought-tolerant. Below are the steps to sow Horehound seeds:

1. **Timing**: Horehound seeds are typically sown in the Spring or Autumn. In the spring, wait until after the last frost date. In Autumn, sow the seeds about 6-8 weeks before the first frost to allow for germination and some growth before winter.

2. **Preparation**: Before sowing, prepare the soil by removing any debris and weeds. Horehound prefers well-draining, slightly alkaline soil. If your soil is acidic, you can add lime to raise the pH. Work in some organic matter to improve soil structure and nutrients.

3. **Sowing**: Sow the seeds thinly on the soil surface. They require light to germinate, so do not cover them with soil. Instead, gently press them into the soil to ensure good contact.

4. **Spacing**: Space the seeds approximately 12-18 inches apart. Horehound can grow up to 2 feet tall and wide, so they need some room to spread out.

5. **Watering**: Water the area well after sowing, but do not overwater. Keep the soil evenly moist, but not waterlogged.

6. **Germination**: Horehound seeds can take anywhere from 14 to 30 days to germinate. Keep the soil temperature around 70°F (21°C) for optimal germination.

7. **Thinning**: Once the seedlings are large enough to handle, thin them to the desired spacing. This usually occurs 4-6 weeks after germination.

8. **Care**: Horehound does not require a lot of attention. Keep the soil moist, but not saturated, especially during the first year. It is relatively pest and disease-free.

9. **Transplanting**: If you are starting seeds indoors, you can transplant the seedlings outside once they are 2-3 inches tall and after the last frost date. Harden them off for a week before moving them to their final location.

10. **Sunlight**: Horehound prefers full sun but can tolerate partial shade. Choose a spot that receives at least 6 hours of sunlight per day.

11. **Fertilization**: Horehound does not require a lot of fertilizer. In fact, too much nitrogen can reduce the concentration of the medicinal compounds in the plant.

12. **Pruning**: Prune the plant back to about 6 inches in the spring to encourage bushy growth and prevent it from becoming too leggy.

13. **Patience**: Horehound can take a few years to reach maturity and produce a substantial amount of leaves for harvest.

Remember that Horehound is a hardy plant, but it can take some time to establish itself. Once it does, it can self-seed and spread, so you may need to control its growth to keep it in check. Enjoy watching your herb garden flourish with this useful and attractive plant!

Do not take internally or use for medicinal purpose without expert medical advice.