Seeding Advice

Wild flower meadows

Weed control is critical to the successful development of wild flower meadows.  It is very important to start with a site free from weeds.

On farmland deep ploughing to a depth of 15 to 20 cm, will help bury vegetation and bring less fertile soil to the surface.   For smaller areas rotavators can be used and weeds killed off with an herbicide.  The ‘stale seed bed’ technique is effective and involves allowing weed seedlings to germinate for some 4 to 6 weeks after seed bed cultivation and then using Glyphosate to kill the young weeds.  The more often the treatment can be repeated the fewer residual problems experienced with weeds.  Soil cultivation normally comprises ploughing and secondary cultivation to create a tilth using harrows, discs, tined cultivators or rotavator.

The optimum time for sowing is late summer/early autumn, with March to early May (especially on clay soils) the next best window.  Seed requires warmth and moisture to germinate and so should be sown later in Spring on cold, clay soil than on light sandy or chalky soil.  However, seed can be sown throughout the winter given good soil conditions.  To get an even distribution it helps to sow half the seed (at half the seeding rate) in one direction and the other half over the whole area again at right angles.  Sow onto the surface but do not harrow or rake in.  Instead use one or two passes from a ribbed roller to firm and level the seed bed and create good seed soil contact.  If it is a very small area, then walk over the site to create good seed to soil contact.

Seeding rates for grass and wildflower meadow mixes are normally 4 grams per m².  In difficult conditions the seeding rate can be raised to 5 gm/m², e.g. on sites considered to be at risk from erosion.  On large sites seed rates can be lowered to as little as 2 gm/m², when clients are prepared to allow a wild flower meadow to develop gradually.   Wildflower plug plants can be introduced after the sowing of the seed mix.

The grass management programme during the first year is critical for success.  During this season the vegetation should be cut down to 5-7 cm whenever the sward reaches 10-20 cm.  The number of cuts required will depend on the soil’s fertility and can range from 1 to 4.  This cutting regime has the purpose of eliminating any annual weeds by not allowing them to flower.

A Guide for Subsequent Management Regimes

There are a number of options for subsequent management, depending on what your objectives are, the soil fertility and the weather conditions in the individual seasons.

The classic wild flower meadow is a hay meadow with a cut taken in late July/early August and an aftermath cut in the autumn.  The cuttings are removed, especially after the hay cut.  This management regime aims to replicate the practice of taking hay in the summer and grazing the field over the winter.

If the soil is fertile, or the growing season is especially good, which would result in very strong grass growth swamping the wild flowers, lodging (falling over) and looking untidy in the summer, the management regime can be modified.  One, and possibly two additional cuts (if the site is especially fertile) in the spring and early summer (i.e. April/May) can be introduced.  Cutting at this time reduces the grass’s vigour, results in a shorter sward and a later flowering.

The hay cut is taken in early August, when the cuttings must be removed, followed by an aftermath cut in the autumn.

Spring Flowering meadows have their first cut taken in late June.   A second cut can be made in late July/early August followed by an aftermath cut in the Autumn.  This management regime encourages spring flowering wild flowers (e.g. Cowslips, Cuckoo flowers) and the shorter wild flowers (e.g. Birdsfoot Trefoil, Daisies and Selfheal) during the summer.

Late Summer flowering meadows can be encouraged by only cutting in the autumn; but adding one or two spring cuts if especially fertile.

Paths should be cut through the meadow to improve access and to demonstrate that the wild flowers are cared for.

Woodland seed mixes

The shade level of the site should be sufficient to at least severely weaken grass growth.  No site preparation is necessary in weed free, semi-shaded or shaded areas.  If vegetation levels are high some initial ground pre-treatment is necessary with herbicide or mulch to control weeds.  Seed may be distributed by hand in late September/October or February/March.  Some of the species require a period of cold for germination.  The seeding rate is about 1 gram/m².  In small areas it may help to rake the seed in a little but do not bury it.  In large scale seeding operations good results are obtained without raking.  Most species will germinate in the first season.  Red campion are usually the first plants to establish themselves.  Bluebells are slower germinating, requiring a warm and a cold treatment to germinate.  They may not germinate until the second season.  Thereafter it can take 4 or 5 seasons to produce flowering bluebell plants.  An annual cut may be taken in mid-Summer.

Yellow Rattle seed

Yellow Rattle is a valuable and attractive wild flower in its own right and is typical of traditional hay meadows.

Yellow Rattle is an annual which germinates in early March and its seed ripens in July before the hay cut.  The seed then over-winters on the soil surface.  The plant is semi-parasitic on grasses and can therefore suppress grass growth.  This is particularly useful in more vigorous grassland where other wildflower germination and establishment would otherwise be inhibited by competition from the grass.  The poorer the grass growth and the more ‘open’ the sward the more species of wild flower that can be accommodated.

No fertilisers should be used!

Yellow Rattle seed is one of the very few wild flower seeds that can be oversown on grass, but the grass should first be cut down to 2-3cm and raked or harrowed to expose 50% bare soil. Sow thinly by hand any time from August through to December. The seed needs to over-winter to be vernalised naturally in cold, moist conditions.   As a rough guide 0.5g to 1 gram is required per m² (i.e. approx. 3 kg/acre or 7.5 kg/hectare).  It is important to ensure that the grass is fairly short (maximum 4-5 cm) by the end of February so that the seedlings can more easily push up through the sward in early spring.

The grass should not be cut from early March through until the end of July, to allow the Yellow Rattle seed to ripen.  (Grass which is heavily summer grazed by rabbits will not be appropriate).  It is important that the grass is then cut quite short and the cuttings removed.  This will also help spread the Yellow Rattle seed around.  In subsequent years yellow rattle can be sustained under a typical hay management regime i.e. hay cut in late July/early August, followed by an aftermath cut in the autumn.

Cornfield Annuals Seed Mix

Cornfield annuals seed may be sown onto cultivated poor, medium or fertile soils at 1 to 2 grams per square metre. The optimum sowing period is autumn to early spring and flowering will occur in 3-9 months, reaching a peak in June.  A late spring sowing will shift flowering into middle and late summer.  Cornfield annuals can be re-established each year by rotavating the dead plants.

Cornfield annuals can be sown in addition to a perennial meadow seed mix to produce some colour interest in the first year.  Important Note:  Once the cornfield annuals have flowered and before they set seed or collapse, the area should be cut and the cuttings removed so that this lush growth does not smother the emerging perennial seedlings.

Last Updated: 31/03/2011