Information and Advisory Note Number 106 Back to menu
1.1 This note discusses the potential for creating grasslands approximating to
semi-natural communities on land which has previously been cultivated. It gives
advice on sources of wildflower seed and lists recommended seed mixtures for
different situations. It also gives advice on grassland establishment and
subsequent management.
1.2 Wildflower seed mixtures should not be used to replace semi-natural
vegetation or indeed semi-improved vegetation where significant elements of the
semi-natural vegetation remain.
1.3 It may be possible to enhance the species-richness of semi-improved swards,
without replacing them completely, by strip seeding wildflower seed in rows, by
sowing wildflower seed after partial cultivation by rotovator or by introducing
plug plants. These methods are currently under investigation by the Institute of
Terrestrial Ecology at Monks Wood in Cambridgeshire.
1.4 The creation of wildflower grasslands has the greatest chance of success on
soils of low fertility, such as shallow soils and upper slopes. Wildflower
grassland creation on fertile soils requires more work to control undesirable
species and maintain the balance of sown wildflower species.
2.1 The experience of set-aside shows that arable fields abandoned to set-aside tend to develop perennial cover very slowly. Annuals such as annual meadow-grass (Poa annua) and groundsel (Senecio vulgaris) tend to dominate initially, together with volunteers from previous crops. After five years the vegetation is generally species-poor and dominated by a few perennial grasses together with species such as white clover (Trifolium repens), creeping buttercup (Ranunculus repens) and spear thistle (Cirsium vulgare). So grassland creation by natural regeneration is unlikely to be suitable for most situations, though it may be worth pursuing near to existing semi-natural grassland which can act as a seed source.
3.1 Successful wildflower grassland establishment depends
upon the ability of the desired plant species to germinate, establish and persist. The main factors likely to limit
success are:
• the high nutrient status of soil which has been previously fertilised and
• the seed bank of competitive and invasive species in soil which has previously
been cultivated.
High nutrient levels encourage the rapid growth of competitive species, leaving
no room for the slower growing species typical of unimproved grasslands.
However, recent trials conducted by SNH and SAC have shown that, despite these
limitations, it is possible to establish vegetation approximating to
semi-natural grassland on previously cultivated land
3.2 It has been suggested that methods to reduce the residual fertility of
ex-arable soil
can improve the establishment of wildflower
grasslands. For example, nutrient offtake can
be maximised by continuous cropping without adding fertilisers but this may take
many years. Topsoil stripping is effective but likely to be too drastic a
solution for many land-managers, particularly when they rely on short term
funding.
3.3 The effects of the arable weed seed bank can be minimised by careful
preparation of the seed-bed and by careful control of undesirable species after
germination. Further details are given in section 5.
4.1 There is conflicting evidence on the
scientific justification for using only wildflower
seed of local provenance. On the one hand,
different ecotypes of a species separated by a
mile can be more genetically distinct than
populations from similar habitats separated by large distances. On the other hand, the
introduction of plant material differing in
chromosome number from the local
population could lead to hybridisation and
consequent sterility in the local population.
This possibility, though remote, is the chief
argument for SNH recommending that locally
sourced seed should be used wherever
possible and certainly adjacent to important
sites for nature conservation.
A second argument is that any supply of seed is almost invariably contaminated
with species other than those required. Locally sourced seed can only be
contaminated with local species while non-local seed may be contaminated with
species not native to the locality.
4.2 Until recently there has been little alternative to obtaining wildflower
seed from the large seed companies based in England. Some of the seed supplied
is foreign and most of the ready-mixed wildflower mixtures on offer contain
species which are not native in parts of Scotland. This situation is changing
and it is now possible to buy cultivated seed of Scottish provenance, as single
species and in mixtures, as well as seed mixtures harvested directly from
Scottish sites. A list of suppliers is included at the end of this note.
4.3 The Farming and Wildlife Advisory Group (FWAG) in Scotland is leading an
initiative to encourage land-managers to harvest seed from semi-natural
grasslands for local use. This will be particularly appropriate for schemes
funded under the Countryside
Premium Scheme (SOAEFD 1997) and its successor scheme, which support both the
management of existing species-rich grassland and the creation of new
species-rich grassland. It makes sense that, where appropriate, the existing
species-rich grasslands should supply seed to the new ones.
4.4 Hay bales from semi-natural meadows contain the seed of grassland species,
many of which are not obtainable commercially. Spreading hay bales can be an
effective way of scattering seed but is laborious and tends to give
unpredictable results. Much depends on the thickness of hay spread (too thick a
layer of hay can suppress germination) and on subsequent weather conditions.
Seed production of individual species is affected by the time of hay cut and by
weather conditions from year to year.
4.5 Details of procedures for collecting, cleaning, storing and propagating seed
are included in the publications of Wells et al, listed in section 14.
5.1 Given that a suitable wildflower seed mixture has been selected for the
particular ecological conditions of a site, successful establishment relies on
good seed-bed preparation, good control of undesirable species and careful
management, especially in the first year.
5.2 Both spring and autumn sowing can be successful and autumn sowing is usually
recommended in the south. However, seedbed preparation for an autumn sowing must
be carried out early enough to allow adequate seedling growth before the winter
and this is not always possible in Scotland.
5.3 After the last crop the stubble should be ploughed down in the autumn. If
necessary glyphosate should be applied two weeks before ploughing to control
competitive perennials such as couch grass (Elymus repens). The efficacy of
glyphosate depends on the plant being green and still actively growing. An
alternative strategy is to apply glyphosate pre-harvest of cereal (or grass)
crops.
5.4 A fine seed-bed should be prepared through repeated harrowing and rolling.
This will also encourage the germination of seeds
in the soil seed bank, depleting the seed bank before sowing. This is known as
creating a stale seed-bed. A fine seed-bed with a good tilth is required because
the seeds of many wildflower and grass species are small. It is a common fault
that many seed-beds are too loose and uneven. However, moving the soil too much
can result in soil moisture loss and this may then delay or inhibit the
germination of some species.
5.5 Depending on the area to be sown, the seed can be sown by hand or by
tractor-mounted seed or fertiliser broadcasters. Seed drills can also be used
and may be more appropriate in drier areas and on lighter soils where soil
moisture is limited. However, care must be taken (because of the small seed
size) to sow the seed no deeper than 1 cm. Obvious striping can be avoided by
using a narrow row spacing.
5.6 The grass and wildflower seeds should be thoroughly mixed before and during
sowing to avoid separation. As the quantities of seed are often small it may be
useful to mix the seed with an inert substance (such as fine sand, barley meal
or sawdust) to ensure an even distribution. Where large areas are to be sown, it
is best to sub-divide the land into smaller areas and to sow with weighed
quantities of seed.
5.7 After sowing, the site should be rolled to ensure good contact between the
seed and soil. This encourages rapid germination and establishment.
5.8 Careful management is required during the first growing season to control
competition from undesirable species and to encourage tillering and vigorous
establishment of the sown sward. This is the priority in the first year, so
flowers should not be expected until the second season.
5.9 In the newly established sward, undesirable species can only be controlled
by cutting or spot treatment. Annuals are best controlled by cutting at a height
of 8-10 cm approximately eight weeks after sowing. Cuttings should be removed.
Perennials are better controlled by spot treatment, with glyphosate applied by a
rope wick or similar wipe-on applicator.
5.10 Once established, the sward should be
cut and/or grazed to encourage tillering. The
first cut or opening up of the sward to grazing
should be at least eight weeks after sowing.
Further cuts may be necessary, depending on soil fertility and growing
conditions. Initial grazing levels should be low and carefully monitored.
6.1 A wildflower species mixture intended for use in the countryside should
reflect the semi-natural vegetation of the area in which it will be sown. The
ideal way to achieve this is by sowing a seed mixture which has been harvested
from a local semi-natural grassland. However, until such mixtures are widely
available, the next best option is to use a wildflower seed mixture based on an
appropriate community from the National Vegetation Classification (NVC).
6.2 The four grassland mixtures described in sections 9 to 12 of this note are
modelled on widely occurring NVC communities. They are suitable for use
throughout Scotland. The mixtures can be used as they stand or can be varied for
local use by adding appropriate species. Supplementary lists are included of
species which are not native throughout the whole of Scotland but which can be
added to the basic mixtures in parts of the country.
6.3 These mixtures contain the most frequent species of the community on which
they are based but exclude species which are not native throughout Scotland.
They also exclude species which are too competitive and likely to dominate at
the expense of greater diversity (such as Yorkshire-fog, Holcus lanatus) and
those which are unlikely to be commercially available (such as woodrushes,
Luzula spp, and sedges, Carex spp).
Species of lower frequencies have also been included in the mixtures where they
are particularly attractive or where there are too few species of higher
frequencies to make up a sufficiently diverse mixture. Some species will
inevitably do poorly or disappear over time so it is important to start with a
greater number of species than is expected to survive.
6.4 Wildflower seed mixtures usually consist
of 80-90% grass seed and 10-20% forb seed.
Semi-natural grasslands normally contain
higher proportions of forbs than this but, since
grass seed is normally cheaper than forb
seed, costs can be kept down by maximising
the proportion of grass seed in the mixture. The proportions of the individual
species used will also affect the cost.
6.5 Seed companies tend to recommend sowing rates of 30-50 kg/ha but 20 kg/ha
has been shown to produce good results. Lower sowing rates may also work well,
with careful management.
7.1 Grassland must be managed by cutting or grazing if it is not to become rank
and species-poor and eventually revert to scrub.
7.2 Fertilisers should never be applied since they encourage the rapid growth of
a small number of highly competitive species at the expense of greater
diversity.
7.3 Cutting:
• The MG1 mixture for tall grassland (described in section 10) should be cut
once a year and the other mixtures cut twice. The precise timing should depend
upon local conditions and should mimic a hay cutting regime, with a cut in late
July to early August and another (in place of aftermath grazing) in late
September to October.
• The aim is to maintain a sward which has space for new plants to germinate and
become established but no large gaps which would allow infestations of
undesirable species. Cuttings must be removed or they will smother the new
growth.
• Another reason for removing cuttings is to prevent the return of nutrients to
the sward as the cuttings decompose, thus helping to reduce soil fertility over
time.
• It may be necessary to control invasive species from time to time by
mechanical or chemical means. Care should be taken, when using herbicides, that
only the target plants are affected.
• Although the sward will not be highly productive it may produce a usable hay
crop as long as it does not contain ragwort (Senecio jacobaea).
7.4 Grazing:
• Where light grazing is practicable it is
usually the better choice of management
(except in the case of the MG1 mixture for
tall grasslands) since grazing creates more
diverse conditions than cutting, benefiting a wider variety of plants and
animals. Trampling by stock also creates small gaps in which plants can
establish.
• Cattle are more likely to maintain species-richness in a small area than sheep
or horses, which are more selective and more likely to remove all individuals of
a preferred species.
• Grazing can be seasonal, continuous throughout the year, or following a hay
cut (aftermath grazing). Grazing during the summer will suppress flowering and,
where there are ground-nesting birds such as lapwing and skylark, their nests
can be trampled by grazing stock in spring. So a period of grazing in the late
summer and/or autumn is likely to be the most appropriate grazing regime for
most sites.
8.1 The following sample calculations illustrate the likely costs, at 1998
prices, of using one of the proposed mixtures, the MG5 mixture for neutral
grasslands (described in section 9). Costs of individual species change from
year to year so these are indicative only.
8.2 A mixture composed of 80% grasses and 20% forbs, with equal numbers of seed
of the grass species and equal numbers of seed of forbs, would cost about
£75/kg. The same 80%/20% mixture, made up of equal weights of seed of grass
species and equal weights of forb species, would cost about £67/kg. A 90%/10%
mixture made up of equal weights of seed would cost about £55/kg.
Costs can be significantly reduced by cutting the proportions of the more
expensive species and increasing the cheaper species. For example, an 80%/20%
mixture made up of amounts of equal value of grass seed and of forb seed would
cost about £23/kg
9.1 MG5 (Centaurea nigra-Cynosurus cristatus grassland) is found on neutral soils where there has been a long history of low intensity management of the grassland as meadow or pasture. It is the mesotrophic community of greatest conservation value in Scotland and the most appropriate community to mimic on moderately- or well-drained neutral soils where the vegetation can be grazed or cut regularly. This will be the best mixture for use on most ex-agricultural soils.
10.1 MG1 (Arrhenatherum elatius grassland) is an ungrazed grassland of neutral
soils and is found on sites such as road verges, railway embankments and
neglected agricultural or industrial land. It will be invaded by shrubs if left
completely unmanaged but is appropriate for sites which are rarely cut and can
be allowed to grow tall, such as field margins and road verges. This mixture is
based on the Centaurea nigra sub-community (MG1e) which is the most species-rich
of the MG1 sub-communities.
11.1 U4 (Festuca ovina-Agrostis capillaris-Galium saxatile grassland) is the
typical grazed vegetation of moderately- or well-drained base-poor mineral
soils. It is often heathy and in fact heathland creation should always be
considered as an alternative to grassland creation on acid soils. Many of the
more typical species of this community (such as mosses and sedges) and the more
attractive species (such as common dog-violet, Viola riviniana, and
bitter-vetch, Lathyrus montanus) are unavailable commercially so this is
inevitably a short species list. However, this reflects the nature of the
community, which is not normally species-rich.
12.1 MG8 (Cynosurus cristatus-Caltha palustris grassland) is found on seasonally
inundated land by streams and rivers, and also on land receiving a constant
trickle of water from springs, flushes and seepage lines. This vegetation was
once typical of water meadows, which were deliberately flooded in order to warm
and enrich the soils in spring and so stimulate an early bite from the sward.
Poaching may be a problem if the vegetation is heavily grazed when the ground is
wet.
Jane MacKintosh
Advisory Services
Scottish Natural Heritage
2 Anderson Place
EDINBURGH
EH6 5NP
Tel: 0131-4474784
Anna Christal
Scottish Agricultural College
Crops Division
Bush Estate
PENICUIK
Midlothian
EH26 OPH
Tel: 0131-535 3311
Crofts, A. 1994. How to create and care for wildflower meadows. Lincoln: The
Wildlife Trusts.
Crofts, A.& Jefferson, R.G. (eds). 1994. 777e Lowland Grassland Management
Handbook. Peterborough: English Nature and The Wildlife Trusts.
Rodwell, J.S. (ed) 1992. British Plant Communities Volume 3, Grasslands and
montane communities. Cambridge: Cambridge University Press
Wells, T.C.E., Bell, S. & Frost, A. 1982. Creating attractive grasslands using
native species. Nature Conservancy Council, Peterborough.
Wells, T.C.E., Frost, A. & Bell, S. 1986. Wildflower grasslands from crop-grown
seed and hay bales. (Focus on nature conservation No 15.): Nature Conservancy
Council, Peterborough.
Wells, T.C.E., Cox, R. & Frost, A. 1989. The establishment and management of
wildflower meadows. (Focus on nature conservation No 21.: Nature Conservancy
Council, Peterborough.
Flora locale is a partnership project of Plantlife and the Institute of Ecology
and Environmental Management, with funding from WWF (UK) and English Nature. It
is looking at some of the problems caused by the use of wildflower seed in
habitat creation schemes, such as the introduction of non-local seed and
non-native species into the
countryside. Flora locale suggests solutions such as an accreditation scheme for
growers and suppliers of native provenance plants. The project also produces
technical guidance notes on aspects of habitat creation, including a code of
practice for collectors, suppliers and growers of wild plant genestock.
For further information contact:
Flora locale
36 Kingfisher Court
Hambridge Rd
NEWBURY
RG14 5SJ
Tel: 01635 550380
The following companies produce wildflower seed of British provenance:
Scotia Seeds
Branxton
Boarhills
ST ANDREWS
Fife
KY16 8PR
Tel: 01334 880241
(Sells seed of Scottish provenance.)
Meadowlands Ltd
The Park Lodge
Park Avenue
WORTLEY
S. Yorkshire
S30 7DR
Tel: 0114 283 0322
(Sells mixtures harvested from SSSIs and
other species-rich grasslands.)
Emorsgate Seeds
The Pea Mill
Market Lane
Terrington St Clement
KINGS LYNN
Norfolk
PE34 4HR
Tel: 01553 829028
(Specifies from which English county the stock
seed of each species was collected.)
Naturescape
Little Orchard
WHATTON IN THE VALE
Notts
NG13 9EP
Tel: 01949 860593
Really Wild Flowers H.V.
Horticulture LTD The Shop,
The Street Sutton Waldron
BLANDFORD FORUM
Dorset
DT11 8NZ
Tel: 01747 811778
Johnsons Seeds
London Road
BOSTON
Lincolnshire
PE21 8AD
Tel: 01205 365051
British Seed Houses Ltd
Bewsey Industrial Estate
Pitt Street
WARRINGTON
Cheshire
WA5 5LE
Tel: 01925 654411
John Chambers' Wild Flower Seeds
15 Westleigh Road
Barton Seagrave
KETTERING
Northants
NN15 5AJ
Tel: 091933 652562
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