Guidelines and methods for collecting

1. The Millennium Seed Bank Project say a collection for a species:

  • should come from a minimum of 50 plants to ensure there is good genetic variation
  • must not be made in a way that takes over 20% of the mature seeds of a species that are available on the day

The second of these is important in ensuring collecting does not damage the source population

2. Check whether it looks likely that what you are about to collect is mature seed. You can do this by looking at whether:

  • some plants in the population have already shed their seeds
  • the seed heads, stems near seed heads or fruits have changed colour (often changing from green to brown).
  • pods, seed heads or fruits easily break apart releasing seed
  • seed coats have changed colour (again, often changing from green to brown)
  • seeds are rattling in their pods
  • seeds are hard and dry (seeds that are soft and moist when pressed between fingernails are unlikely to be ripe)

3. Start collecting early in the season. It is easy to miss the first species to ripen. The species our grassland collecting starts with are Field Woodrush and Meadow Saxifrage. I start checking these for ripeness in mid-June

4. To make sure we get at least some seed from a species, we do some collecting as soon as we find it is producing viable seed. If possible, we also collect some later so we are getting seed from across the range of flowering time for that species

5. Collect in dry weather whenever possible. This makes handling, drying and storage of seeds easier

6. Collecting is usually quickest at sites with a high population of the target species

7. If the species you are looking for is spread across a collection site, then take some seed from across the whole site rather than just collecting in one small area. This will help increase the genetic diversity of your seed collection

8. We do almost all our collecting by hand. The method varies depending on the species:

  • With some species, ripe seed is hard to get out of the seed head in the field, so we gather whole seed heads, for example Crested Dog’s-tail and Common Knapweed (we use scissors to cut just below the seed heads for species with tough stems)
  • With others, ripe seeds are easily pulled from the plants, so just seeds are collected
  • Some plants have seeds hidden among a lot of leaf material. Crosswort is an example. We collect whole stems including leaves and seeds and then separate the two once the collected material has dried out

9. With some species (e.g. Aaron’s Rod), it is worth checking seed heads from plants that grew in the previous year as these can still contain seeds

10. In some years, late-flowering plants may produce most of their viable seed after the ideal drilling date for most species (roughly late-August to mid-September). These late ripening species can be added to a site later by hand after the main mix has been sown

11. For each species, we try to collect from more than one local site in order to increase the genetic diversity of the collection

Field woodrush flowering in the first week of April
Field woodrush flowering in the first week of April. Seed may be ready to collect as early as mid-June
Clary with seed ready to collect
Clary with seed ready to collect
Seed collecting
Collecting Wild Carrot (in the container) and Harebell by cutting off ripe seedheads