Seed collection methods from grassland
Harvesting grassland flora
Timing seed collection
- Site management (e.g. grazing, hay cutting)
- Geographic location
Grassland "whole habitat" harvesting
- Offers the only really practical field-scale solution for obtaining seeds of known local origin
- This approach is the only way to obtain the full range of native grasses that are associated with native grassland
- This technique is invaluable for restoring or extending ecologically sensitive sites.
Efficiencies of scale
Enables large quantities of seed to be collected with minimal effort
One hectare of land harvested produces sufficient seed for an equivalent area (but seed can be spread more thinly if desired, especially if used to inoculate floristically-poor grassland).
The composition of harvested seed mixtures directly reflects that of the donor site
Many species are sampled including a number that are simply not available from usual commercial sources
The overall diversity of meadow harvested mixes is often much greater than can be obtained in proprietary seed mixes
However, the composition of seed collected (species by quantity and weight) will depend on what is ripe at the time of harvesting:
Late summer harvesting leads to higher proportions of grass seed in the mix and spring-flowering species may not be well-represented.
The seed-harvesting window is brief
Timing is site- and weather-dependent.
Harvested seed can be sown directly onto a prepared donor site (although the best time to sow seed is late August-end September)
More usually seed is stored for later use, as the optimum window for seeding does not often coincide with the harvest
When seed is harvested to reinstate vegetation following engineering works several years may separate harvest and sowing (viability can be maintained only if the seed is correctly stored).
Can be uneconomic, difficult and sometimes impossible in years when hay fields are sodden by prolonged wet spells
Hay cutting or grazing must be delayed to allow seed to ripen
Only suitable on level accessible sites which have a relatively large area of floristically rich grassland.
English Nature's protocol for harvesting from grassland Sites of Special Scientific Interest
Either harvest seed from no more than 30% of the meadow in any one year, or
(Protocol as @ January 2003)
Harvesting methods and equipment
- The most effective and wildlife-friendly method for whole-field harvesting
- Lightly brushes seed off, with minimal chaff and minimal wildlife "bycatch"
- Takes only a proportion of seed ñ unripe seed won't be taken (plants such as Yellow Rattle will still seed sufficiently to maintain their populations)
- Brush harvester is easily transported
- Offset versions don't flatten the sward prior to harvesting
- Hay can be cut afterwards.
- Won't take seed easily from some species (e.g. Scabious, Knapweeds)
- You may have to follow-up with some manual collections.
- Commercially available equipment *indicates machinery that can be trailed offset
- *Emorsgate Brush Harvester (requires standard 40hp agricultural tractor with 3- point linkage and PTO) - for large areas of grassland
- *Eyre seed harvester (trailed using standard tow bar/tow ball fixing)
- Rekord Seed Harvester (for use with pedestrian tractor so suitable for smaller sites)
- Turf-cleaning machines (e.g. Charterhouse Turf Tidy).
Combining - using a plot combine
- Available mainly as second-hand machinery (otherwise not widely available)
- Used by commercial nurserymen and research stations
- May be available for hire
- Less efficient than a good brush harvester for collecting species having light seeds (e.g. Yellow Oat-grass Trisetum flavescens, Yarrow Achillea millefolium)
- More efficient at collecting seed from species holding seed tightly (e.g. Knapweeds) ñ that can be missed by a brush harvester
- Can be calibrated for different seed types
- Cuts grass for hay and removes seed at same time
- Used for harvesting some commercially grown wild flower crops.
- Suitable for whole-field harvesting or for smaller sites
- Timing is critical
- Carry out when the maximum number of species have ripe seed, but not too late in the season
- Mow or forage-harvest the sward
- Loose bale it straight away or blow the cuttings direct into a trailer
- Transport it directly to the receptor site
- Spread the hay immediately to allow it to dry and the seed to drop out (bales can be rolled out)
- Leave it for a minimum of one week in dry weather and three weeks in wet weather to allow seed to ripen and fall out
- Grazing or using a swath turner followed by rolling can be useful to aid seed shedding and bedding in.
Alternatively, hay can be spread thinly on bare ground sites and not removed, or can be chopped before spreading and left.
- Suitable for receptor sites very close to the donor site
- Farmers can collect their own seed, using standard agricultural equipment.
- Hay is bulky and costly transport - so this method is only suitable for sites close by
- Timing is critical - hay must be collected and spread within a few hours to prevent seeds dropping out, rotting or being destroyed by heat.
- A usable or saleable crop of hay is lost (on a productive hay meadow, this could be equivalent to losing between 20 and 70 hay bales).
- The sward can be manually or mechanically cut
- Rake grass immediately and put into a trailer
- Spread it directly on to the receptor site.
- Agricultural machinery isn't necessary
- Standard car with towbar and trailer
- Petrol/2-stroke brush cutter or heavy duty mower
- Scythes, reap hooks and yard broom
- Hay forks (to strew hay from trailer)
- Labour - could be a volunteer conservation task.
- Readily available
- Reasonably cheap
- Easily carried to inaccessible sites
- Designed for collecting leaves from parks and gardens
- Good for using on steep ground and land not accessible to brush harvesters or pedestrian mowers
- Can be used to collect seed from individual species and small sites.
- Buy heavy duty, good quality, petrol/2-stroke versions
- Disable the internal leaf-shredder if present (usually a fan) to prevent damage to seed*.
- *modifications should be undertaken by a person knowledgeable about the technical specifications of the equipment, are at user's risk and may invalidate the manufacturer's guarantee.
To reduce impact on invertebrates
- Disable the leaf-shredder (see above)
- Spread the seed on to a poly sheet laid out on site for at least half-an-hour immediately after collection (to enable invertebrates to crawl off or fly away).
Other pedestrian equipment
- Commercial leaf vacuums ("billy goats")
- Small brush harvesters (e.g. the Rekord harvester)
- small sites or small populations (e.g. wild flowers on road verges)
- species which are difficult to mechanically harvest (e.g. Field Scabious Knautia arvensis, Harebell Campanula rotundifolia, orchids).
Equipment for hand-picking
- Waterproof felt pen - to write on collecting bags (species name, date, where collected)
- Collecting bags (not poly bags, which will sweat and rot the seed), e.g.
- Strong brown paper or woven polyproylene flour bags
- Old envelopes
- Home-made from muslin (cheap to buy, available from fabric shops)
- Cutting and raking equipment can be useful, e.g. strong pair of kitchen scissors or pruners, reap hook or slasher, rake.
Keep both hands free by tying the collecting bag around your waist (remember string).
Beware hazardous plants, such as Wild Parsnip Pastinaca sativa , which produces phytotoxins that can cause painful blistering following skin contact and exposure to sunlight.
Methods of hand picking
- The density of the plants and ripe seed heads
- The ripeness of the seed
- The species.
- Stroking, rubbing or shaking seed heads so seed falls into collecting bag
- Cutting or picking ripe seed pods or stems holding one or more seed-heads.
- cut off the ripe seed heads (e.g. using a strong pair of scissors, or reap hook)
- rake up the cuttings (e.g. for low-growing plants such as Birdísfoot Trefoil, where growing densely on short turf) or
- cut the stem and put it or allow it to fall into the bag.
Paying for seed
Drying and cleaning seed
- Uncleaned seed can be put down directly on to a receptor site without removing chaff if spread by hand.
- Other seed should be dried, cleaned and removed from pods and capsules.
- Plant disease (e.g. fungi, viruses)
- Invertebrate predators.
Seed to be drilled should always be dried and cleaned, or chaff will block the drill.
Drying the seed
Drying racks: Weald Meadows Initiative
Once seed has been harvested it is taken back to the farm and spread thinly on specially made drying racks. These are made of wooden frames covered with a fine polypropylene mesh. The construction allows for air to circulate between the stacks of seed, and the racks can be moved with a forklift.
Manual seed cleaning
A variety of methods will be required to remove stems, petals and leafy material,
and to remove seed from husks and pods.Peter Greenhalf/CA
Treading or light crushing can be used for legumes with hard-coated seeds and unexploded pods (for small quantities, the seed can be put into a poly bag and bashed with a rolling pin to break up the dried seed pods and free the seed).
Light mesh racks, standing proud of the ground, with a diameter of 1 centimeter can be used on site to reduce the quantity of stem and leaf matter when unloading the seed hopper and before spreading the seed to dry on polythene sheets.
Drying seed on site can be thwarted in wet weather. It will also be more difficult on small sites that are sheltered by large hedges or in wooded areas, where humidity remains high even in warm weather.
Manual seed-cleaning is time-consuming and not 100% effective. For large quantities of seed, mechanical methods will need to be used.
Store clean, dry seed only
Put in sealed labelled jars, poly bags, sacks or dustbins
Keep in a cool, vermin-free, dry place
Most wild flower and grass seed can be stored and remain viable for many years
Seed requiring hardening must be chilled at 0 degrees C or less for a week or more prior to sowing
Some species requiring hardening will not germinate in spring unless sown the previous autumn, even if pre-chilled.
http://www.theseedsite.co.uk/db9a.html for useful information on the seeds of different species and genera, including many British native species
http://www.wildseed.co.uk/Prices/Singles/flowerorigin.htm and http://www.wildseed.co.uk/Prices/Singles/grassorigin.htm for information on the sizes of seed for different grassland species.
The following links are designed for North American wild flowers, but some of the general principles will apply to
harvesting wild flower seed in other countries.
Collecting wild flower and prairie seed
- Guidelines for seed collecting (Lady Bird Johnson Wildflower Centre)
This technical note is one of a series produced by Flora locale, in association with English Nature, to encourage good practice in the use and collection of native flora. It may be downloaded and distributed electronically or by simple photocopies but may not be published, placed on a website or sold for commercial gain. To seek permission to publish this note, or extracts from it (electronically or otherwise) please contact email@example.com
Information in this note is provided for guidance only and focuses on wild seed collection in the UK. Flora locale accepts no liability over its use or application by individuals, businesses or institutions. See also the Technical Notes: Equipment for harvesting wild flora and heather and Harvesting and using heather seed. Training courses are available to practitioners wishing to learn more about issues covered in this Technical Note. See the training section of the website. Special training and demonstration events can also be organised by request.
© Flora locale and English Nature 2003. Photographs © as credits.
AcknowledgementsFlora locale is grateful for financial support received from the Esmee Fairbairn Foundation and Ernest Cook Charitable Trust, which funded the production of this Technical note.
With thanks to Tony Robinson (English Nature), Penny Anderson, Richard Brown (Emorsgate Seeds), Dawn Brickwood (Weald Meadows Initiative) and all contributors to the Enact magazine features Options for seed harvesting techniques (published in Enact Winter 2001 and Spring 2002) and Diversity from Molinia moorlands (Enact, Winter 2002). Back issues of Enact can be obtained from British Wildlife Publishing, tel: 01256 760663, firstname.lastname@example.org).
Enact has been superceded as the magazine Conservation Land Management, available on subscription from the same address.
Additional information, either text or images, which will enhance the usefulness of this technical note would be appreciated. Please email Flora locale using the above address.
Compiled by Sue Everett, Flora locale.