Envelope Garden

Vegetable and flower seed saved from a small backyard, one paper envelope at a time.

Germination tests on wet paper towels: what two-year-old seed can still do

26 September 2026 · 3 min read

Before I plan the beds I want to know which envelopes in the shoebox are still alive, so the last week of September is testing week. The method is the simplest one there is: count out ten seeds, lay them on half a damp paper towel, fold it over, slide it into a plastic bag with the envelope’s label written on in marker, and set it on top of the refrigerator where it stays around 75 °F. Check at seven days, count what has sprouted, check again at fourteen, and write the final number on the envelope itself.

This year I tested twenty-two envelopes, which took a Sunday morning to set up and about five minutes a day after that. The results sort cleanly by what the seed is, not by how old it is.

  • Tomato, 2024 harvest: 9 of 10 up by day seven. Two years old and barely slowed down.
  • Tomato, 2025: 10 of 10.
  • Bush bean, 2024: 8 of 10, though two of those had a rotten spot and might not have made it in soil.
  • Lettuce, 2024: 6 of 10, all by day five. Lettuce, 2025: 9 of 10.
  • Onion, 2024: 1 of 10. Onion, 2025: 7 of 10. Onion seed is famous for lasting about a year and it earned that reputation here.
  • Parsnip, 2025: 0 of 10 at fourteen days. I will buy parsnip seed every year and stop pretending.
  • Zinnia, 2025: 8 of 10. Cosmos, 2025: 10 of 10. Calendula, 2024: 7 of 10.
  • Squash, 2025, hand-pollinated: 10 of 10, big and fast.

Two lessons that were not about the numbers. First, the plastic bags must be left slightly open or the towel grows a gray mold by day five that makes the count impossible; two of my bags went that way and had to be redone. Second, a seed that sprouts on a paper towel at 75 °F is not the same as a seed that comes up in cold April soil. My rule from last year holds: whatever the towel says, I sow outdoors a third thicker than the count suggests and thin later.

Everything under 5 of 10 goes in the compost, except the onion, which I will sow thickly in a flat and see. Everything over 8 I can share, and the tomato envelopes from 2024 will go to the seed swap in February with a note saying 90 percent in September 2026, two years old, keep cool.