What Happens If You Want to Grow Seeds Indoors but Don’t Have the Space?

Consider winter seed sowing. While we are strong advocates for growing seeds indoors, we understand that not everyone has the room or the budget to buy grow lights. This year, we experimented with winter seed sowing, which involves growing seeds in opaque jugs outside in the cold.

It was an extreme leap of faith in Mother Nature, trusting that these seeds would germinate despite the bitter cold. We initially thought the experiment had failed, as the seeds didn’t germinate until the first week of May.

So, Let’s Back Up: What Is Winter Sowing?
Winter sowing involves planting seeds in containers that act as mini-greenhouses and leaving them outdoors during the winter. You can sow the seeds at various times—some people start as early as January, while others begin later. We started at the beginning of March.

If you’re sowing perennials, ensure there are a couple of weeks of below-freezing weather beforehand. Many perennials require cold stratification to germinate.

For warm-weather crops like tomatoes and peppers, it’s best to sow them about a month or two before your local frost date.

Supplies Needed for Winter Seed Sowing:
Opaque containers: Vinegar, juice, or water bottles work well. Look for containers with narrow tops. We also used large containers with flat tops and drilled holes in them. The goal is to create a mini-greenhouse.
Instructions for Preparing the Jugs for Winter Sown Seeds:
Cut the bottles: Cut about 4 inches from the bottom, leaving part of the bottle attached as a hinge.
Drill drainage holes: Drill a few holes in the bottom of the bottles.
Drill weep holes: Add weep holes about an inch from the bottom on all sides to allow excess snow and water to drain.
Add potting soil: Fill the bottom with 3-4 inches of moist potting soil.
Plant seeds: Space the seeds as you would when planting in the garden. Over-seeding is fine if you’re using older seeds, but you’ll need to separate the plants later.
Choose fresh seeds: Use first-year seeds whenever possible for a higher germination rate, especially for crops like onions and spinach.
Seal the bottles: Use duct tape to secure the bottles and remove the tops. You may need to reapply duct tape during the winter.
Ventilate on warm days: Open the bottles on 70°F+ days to prevent overheating. Reseal them when temperatures drop.
Water from below: Place the bottles in a tray of water so the soil absorbs moisture from the bottom. Avoid watering from above, as it may dislodge the seeds.
What to Watch Out For:
Delayed germination: During a very cold winter, seeds may not germinate until consistent 70°F+ weather arrives. Our seeds didn’t germinate until the first week of May.
Protect from frost: If seeds germinate during winter, cover them with a blanket during freezing weather.
Soil dryness: In areas with dry winters or prolonged cold spells, soil can dry out. If this happens, use a boot tray filled with water to hydrate the jugs from below.
Avoid top watering: Watering from the top may dislodge seeds, disrupting germination.
Reflections on Winter Seed Sowing:
Patience is essential: This method requires a lot of patience. If you’re not a patient person, winter seed sowing might not be for you.
Prepare for potential failure: If seeds fail to germinate, you’ll need to buy plants. Given the late germination date, re-seeding isn’t feasible.
Comparison to indoor growing: Indoor growing allows for reseeding if needed. With winter sowing, you don’t have that flexibility.
Cold weather challenges: Be prepared to protect germinated plants from sudden cold snaps.
Germination timing: Our winter-sown seeds germinated in May, which is much later than our indoor plants would have been ready for transplanting.
Seedling size and strength: Winter-sown seedlings were smaller than their indoor counterparts but surprisingly stronger.
Interestingly, some perennials didn’t germinate at all, likely due to old seeds. For example, catnip—an easy germinator indoors—had few seeds germinate in the jugs.

Winter seed sowing can be a rewarding but challenging method. If you’re patient and prepared to face a few hurdles, it might just work for you!