Growing radishes in a pot: the fastest first harvest

If you want proof that you can grow food, start with radishes. Depending on the variety they are ready 20 to 45 days from seed, they take light frost, and a small pot gives you a useful handful. They only ask for three things: cool weather, enough sun and room for each root.

The basics

• Pot: at least 6 inches deep. A 1–3 gallon pot gives you a useful handful; 2 quarts is the minimum.
• Sun: sources differ, from 3–5 hours to 6 or more. Aim for 6. In too much shade you get leaves and no root.
• When: sow 2–4 weeks before your average last spring frost, and again in late summer for a fall crop.
• Start from: seed only, sown where it will grow.

Sowing

Sow seeds about ½ inch deep and 1 inch apart. They sprout in 5–10 days once the mix is above 40°F. Instead of the whole packet at once, sow a few more every 10 days or so, so the harvest does not arrive all on the same day.

The step beginners skip: thinning

As soon as the seedlings are up, thin them to 2 inches apart. It feels wasteful, but crowded radishes make all tops and no roots. Too much heat and too much shade do the same.

Water and feeding

Keep the mix evenly moist. A dry spell followed by a soaking cracks the roots and makes them hot. Radishes are light feeders: the fertilizer in the potting mix at planting is enough, and extra nitrogen grows leaves instead of roots.

When to pull them

Pull when the roots are about 1 inch across; brush the mix away from the top of the root to check. Do not wait. Radishes stay good for only a short time before they turn spongy and hot, and summer heat above about 80°F makes them bolt, turn bitter and go hollow.