Seed Starting Herbs Indoors
Starting herbs from seed indoors gives you a head start on the growing season, access to varieties not available as transplants at garden centers, and the satisfaction of growing a plant from scratch. The process is straightforward once you have the basic setup.
What You Need
- Containers: Cell trays, peat pots, small plastic pots, or recycled yogurt cups with drainage holes. Any container 2–3 inches deep works.
- Seed-starting mix: Use a sterile, soilless seed-starting mix (peat and perlite based). Do not use garden soil or regular potting mix — they are too heavy and may harbor disease.
- Light: A sunny south-facing window may work for a few seedlings, but for best results use a fluorescent shop light or LED grow light positioned 2–4 inches above the seedlings for 14–16 hours a day. Inadequate light produces leggy, weak seedlings.
- Heat: A seedling heat mat (available at garden supply stores or online) raises soil temperature to the 70–80°F range that most herb seeds prefer for germination. Not strictly necessary but speeds things up significantly, especially for basil and peppers.
Sowing
Fill containers with moistened seed-starting mix. Sow seeds at the depth specified on the packet — most herb seeds are tiny and need only a light covering of mix or none at all (some, like dill and oregano, need light to germinate and should just be pressed onto the surface). Mist gently with water. Cover trays with a humidity dome or plastic wrap until seeds sprout, then remove immediately to prevent damping off (a fungal disease that kills seedlings at the soil line).
Germination Times
These are approximate and vary with temperature:
- Basil: 5–10 days
- Cilantro: 7–14 days
- Dill: 10–14 days
- Chives: 7–14 days
- Parsley: 14–28 days (notoriously slow)
- Oregano: 7–14 days
- Sage: 10–21 days
- Thai chili peppers: 7–21 days
Seedling Care
Once seedlings emerge, remove the humidity dome and keep the light source close (2–4 inches above the tops of the seedlings). Water from the bottom by placing trays in a shallow dish of water and letting the mix wick moisture upward — this reduces the risk of damping off. Thin to one seedling per cell once the first set of true leaves appears. Begin fertilizing with a diluted (quarter-strength) liquid fertilizer once seedlings have 2 sets of true leaves.
Hardening Off
Before transplanting seedlings outdoors, harden them off over 7–10 days. Start by placing them outside in a sheltered, shaded spot for a few hours. Gradually increase their time outdoors and exposure to direct sun each day. This prevents transplant shock. See Spring Herb Planting Guide for transplanting timing.