Producing seed crops of native wild flowers and grasses
Flora locale 06/08/2001
This is an agricultural operation, using conventional agricultural methods.
Stock seed should be frequently replenished by collecting from locations in the wild. All collections should follow best practice such as laid out in the Flora locale Code of Practice for Collectors, Growers and Suppliers of Native Flora and the Botanical Society of the British Isles Code of Conduct.
Records must be kept relating to the dates of original seed collections for stock seed, and the origin of all stock (see the Flora locale Code of Practice).
Seed is usually sown in blocks and/or rows on clean (weed-free) ground.
Pests may build up over time, in which case species rows will need to be rotated around the nursery or farm. (Problems tend to be more acute in locations with a wetter climate). Fungicides may need to be applied to control fungal pathogens (e.g. on wild strawberry crops). Selective herbicides should be used with care. Many are not as specific as they claim to be (they could kill the sown species) and may not be licensed for horticultural application.
The seed of some species, such as Oxeye Daisy, can be combined - mini-("plot") combines with 2-m cutting blade are ideal (cost c. £2000 second hand - make sure to choose a make for which parts are still available). The timing of combining must be carefully chosen to ensure that the optimal window for seed collection is chosen. Remember that some species will "suddenly" shed their seed, so the window for harvesting can be easily lost (e.g. Sorrell/Rumex acetosa).
Some species can be brush-harvested. Certain species are better harvested by combine (e.g. Knapweeds/Centaurea sp) as the brush harvester is not very effective at picking them up.
Some species are difficult to harvest mechanically (e.g. Meadow Cranesbill/Geranium pratense has sticky outer seed coverings that can clog up machinery) and will need to be collected by hand.
After collecting, seed should be dried by laying out on polythene sheets in a dry airy barn or polytunnel. Outdoor-drying is fine in dry weather. The seed should be turned daily to enhance the drying process and to reduce the potential for mould growth. Once dry it can be bagged up for a short while before cleaning (an autumn operation).
Large quantities of seed can be cleaned using conventional seed cleaning machinery - this may be purchased relatively cheaply second hand. Sieves and drums can be specially made by an agricultural engineering company to deal with seeds of particular sizes. Manual cleaning using sieves is an alternative approach, time and labour permitting. The objective is to produce seed for individual species which is free of trash and weed seed.
For small-scale operations, seed can be separated from lighter trash by blowing it in front of a fan - the seed will drop down, while the lighter trash gets blown away. Hand-sieves can be used to separate out the seed of different species or to remove large trash initially.
Once cleaned, seed must be stored in a clean dry place in secure containers where it cannot be got at by pests (especially rodents). Insecticides may be used as a precaution against weevils or other insect infestations. The life of seed in store can be considerably enhanced by storing it in a chilled store which is dehumidified. Cold storage will also prevent hatching of invertebrate pests which would feed on seed.
The longevity and viability of seed varies with different species. Yellow Rattle will rapidly lose its viability and should be sown the autumn after collecting but cold storage can extend its life.