Rooted Ramblings: Sowing seeds indoors and in the garden
- Master Gardener Volunteers
Written by Sambooranam (Sam) Kumar, Portage County Master Gardener Volunteers
Planting seeds, indoors or outdoors, creates the right environment for dormancy to break and new life to begin. Watching a seed sprout feels like magic. Starting seeds indoors is a rewarding, inexpensive way to grow hundreds of healthy transplants and get a head start on the gardening season.
Many long-season vegetables and herbs must be started indoors in early spring. Annual flowers also benefit from an indoor start to ensure summer blooms. Check your seed package for this information, then decide whether to start seeds indoors or sow them outdoors directly in the soil.
Season extension options
Cold frames
A cold frame is a raised, bottomless box with a clear cover that acts like a small greenhouse. Tunnels, hot caps, tents, and floating row covers also protect plants from cold and wind, allowing gardeners to start earlier and harvest later.
Winter sowing
Winter sowing involves planting seeds outdoors in covered containers during winter. Clear milk jugs or similar containers act as mini greenhouses. This method works well for gardeners without indoor space for trays, lights, or heat mats.
Seed starting basics
Seed Starting Mix
Use a lightweight germination mix rather than garden soil. It is finer, improves seed-to-soil contact, and drains well, helping roots stay healthy.
Choosing Seeds
Seeds can come from saved crops, neighbors, swaps, stores, or seed companies. Check germination rates on commercial packets. Germination refers to a seed’s ability to sprout, while viability describes its ability to grow into a strong seedling. Older seeds may sprout but produce weak plants.
Sowing depth
Plant seeds about twice as deep as their diameter. Very small seeds should be pressed gently onto the soil surface and lightly covered, if at all. Seeds may be started in their final container or transplanted later.
Temperature, Light & Water
Temperature
Most seeds germinate best between 70–80°F. Warm soil encourages faster germination and healthier roots. Use heating mats or place trays in warm areas during germination, then move seedlings to bright light. After sprouting, lower temperatures to about 65°F to prevent weak growth.
Light
Some seeds require light to germinate, others need darkness, and some have no preference. Once sprouted, seedlings need 12–16 hours of light daily. Grow lights (fluorescent or LED) provide better results than relying solely on windows.
Water
Moisture is critical. Too much water causes root rot, too little kills embryos. Keep soil evenly moist using a mist bottle or gentle watering. Young seedlings can die quickly if allowed to dry out.
Hardening off
Indoor-grown seedlings must adjust gradually to outdoor conditions before transplanting.
- Days 1–3: 2 hours of direct sunlight
- Days 4–7: 5 hours of direct sunlight
- Days 8–10: Full-day sun
Place plants in sheltered areas such as a porch, carport, or under a tree. Monitor moisture closely, as outdoor sun dries soil quickly.
Direct sowing in the garden
Some crops grow best when planted directly outdoors.
- Cool-season crops (late March–early April): radish, lettuce, spinach, peas, broccoli
- Warm-season crops (May): cucumbers, beans, pumpkins, squash
For pumpkins, squash, and cucumbers, create soil mounds 12–24 inches wide and 4–6 inches high. Plant 3–5 seeds per mound and thin as needed.
With proper care and attention to temperature, light, and moisture, your seeds will grow into strong, productive plants. Enjoy the results of your labor and happy gardening!
Sources
- Extending the growing season: start early, end later
- Winter seed sowing
- Seed Starting Mix Recipe
- Are my seeds still good? Testing seed germination
Ohio State University Extension Portage County Master Gardener Volunteer program. As OSU Extension Master Gardener Volunteers, our articles will never endorse specific products or companies. Questions/comments/suggestions/want to find out more/become a PCMGV: 330-296-6432 • OSU PCMGV web • portco.mgv.oh@gmail.com • FB PCMGV • PCMGV Speaker’s Bureau
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