80/20 vs 100% Wildflower Seed Mixes: How to Choose

Every Wildahome meadow mix comes in two formats: 80/20 (80% fine native grasses, 20% British wildflowers) and 100% wildflower (no grass at all). The wildflower selection in each pair is identical — Traditional, Chalk & Limestone, Heavy Clay, and so on. The only difference is whether grass seed is included, and that one difference changes what ground each format suits, how it establishes, and what it costs to cover a given area.

The short answer: sowing bare, cultivated ground into a brand-new meadow? Choose 80/20 — you need the grasses to form a sward. Adding flowers to a lawn, paddock or existing pasture that already has grass, or want a flower-only border or strip? Choose 100%.

80/20 vs 100% at a glance

	80/20 mix	100% wildflower mix
Contains	80% fine native grasses, 20% wildflowers	100% wildflower seed, no grass
Sowing rate	5g per m²	3g per m²
Best for	Bare, cultivated or newly stripped ground	Over-sowing existing grass; flower-only areas; your own blends
Not suited to	Sowing into existing grass (needs bare soil to establish)	Creating a whole new meadow from bare ground on its own — gaps will fill with weeds and coarse grass
Pack sizes	10m² to 2,000m² (plus seed & mulch mats)	20m² to 6,500m² (plus seed & mulch mats)
Habitat selections available	13 (Traditional, Chalk & Limestone, Heavy Clay, Wetland & Pond, and more)	Same 13 selections, wildflower content only

What “80/20” and “100%” actually mean

The number refers to the make-up of the packet, not the finished meadow. An 80/20 mix is four-fifths fine, non-aggressive native grass species and one-fifth wildflower seed by weight. Those grasses aren’t filler — they cover bare ground quickly, hold the soil, out-compete coarse weeds while the slower wildflowers get established, and give the meadow a structure that can be cut, grazed or walked on once it’s mature. A 100% mix is the wildflower component on its own, with no grass seed added.

Every habitat-specific selection — Traditional, Chalk & Limestone, Heavy Clay, Wetland & Pond, Loam & Alluvial, Hedgerow & Banks, Woodland & Heavy Shade, Coastal, Acidic Soils, Restoration, Bee & Butterfly, and Cornfield Annuals — is available in both formats. Pick the habitat match for your soil and site first, then decide 80/20 or 100% based on your starting ground.

Choose 80/20 if you’re starting from bare ground

If you’re creating a brand-new meadow — a stripped field, a cultivated plot, ground that’s been cleared of turf — you need the grasses. Wildflowers alone don’t form a stable, self-supporting sward on open ground: without grass to knit the surface together, gaps open up and get colonised by whatever weed seed is already in the soil, which on most sites is a great deal. The 80/20 ratio has been the standard proportion for new-meadow creation for decades because it gives wildflowers enough grass structure to grow through without letting the grass dominate — provided fertility stays low.

Choose 100% if you already have grass, or want flowers only

If the ground already has a grass sward — a lawn, orchard floor, paddock, or thin existing pasture — you don’t need more grass, you need flowers. Cut it short, scarify hard to expose at least half bare soil, and sow a 100% mix directly into it (adding Yellow Rattle the following autumn will help weaken the existing grass further). A 100% mix is also the right choice for a flower-only bed, verge strip or border where you don’t want any grass at all, or if you’re building your own bespoke ratio — pair a 100% mix with our Native Grass Seed Selection to blend your own 80/20, 60/40, or whatever proportion a specific brief calls for.

Cost: what covering the same area actually costs

Because the sowing rates differ (5g/m² for 80/20 versus 3g/m² for 100%), packs of the same “coverage” number aren’t priced the same — and the two formats aren’t equally cheap per square metre either. Using our Traditional mix as a worked example, at current prices:

Coverage	80/20 Traditional	100% Traditional
150m²	£133 (≈89p/m²)	£194 (≈£1.29/m²)
300m²	£243 (≈81p/m²)	£320 (≈£1.07/m²)

An 80/20 mix generally costs less per square metre than a 100% mix covering the same area, because four-fifths of an 80/20 packet by weight is grass seed, which is cheaper to produce than wildflower seed. That’s not a reason to choose 80/20 for existing grass, though — a 100% mix sown into a lawn or paddock is still cheaper than stripping that ground bare and starting again with 80/20. Match the format to the ground first; cost is the second question, not the first. Exact prices vary by mix and pack size — check the current price on each product page for your area.

Establishment: what to expect from each

80/20, year one: grasses germinate fast and dominate visually; wildflowers are present but modest. Annual weeds often flush in the first season on freshly disturbed ground — cut if growth gets rank and remove the cuttings, but don’t expect a flowery display yet.

80/20, from year two: as fertility drops and the sward settles, wildflowers strengthen and spread. A well-managed 80/20 meadow keeps improving for several years — this is a long-term investment in a resilient, low-input meadow, not an instant display.

100% into existing grass: success depends entirely on how much bare soil you exposed at scarification. Thin scarification means poor germination — most of the seed sits on top of a grass sward it can’t get through. Done properly (at least 50% bare soil showing), expect a visibly flowery first or second season, since you’re not waiting for grass to establish alongside it.

100% as a flower-only planting: the fastest route to colour, since every gram sown is a wildflower. Without any grass structure, expect more bare ground between plants in year one, and be ready to hand-weed or spot-treat more aggressively, since there’s no grass competing with weeds on your behalf.

Both formats need the same underlying discipline: low nutrient soil, no fertiliser or compost, and an annual late-summer cut with the cuttings removed once the flowers have set seed. Full step-by-step guidance is in How to Establish a Wildflower Meadow.

Do this / avoid this

Do this: match the format to your starting ground (bare soil → 80/20, existing grass → 100%) before you pick a habitat selection; test or eyeball your soil type so you choose the right habitat mix; keep fertility low from day one; sow in the recommended windows (spring, March–May, or early autumn, August–September); cut and remove arisings every late summer once seed has set.

Avoid this: sowing an 80/20 mix straight into existing grass (it needs bare soil to establish, and the seedlings will lose to the incumbent sward); sowing a 100% mix onto bare, cultivated ground expecting it to hold on its own (gaps will fill with weeds and coarse grass without any nurse grass to knit the surface); adding fertiliser or compost at any stage (it feeds the grass and weeds at the wildflowers’ expense); cutting and leaving the arisings on the ground (this raises fertility over time and works against the meadow).

FAQs

Can I mix the two formats on one site?

Yes. Many larger or mixed sites use 80/20 on the bulk of an area being created from bare ground, and 100% for borders, verges or existing grassed sections within the same project.

Which is better for biodiversity net gain (BNG) projects?

Whichever matches the starting ground on each parcel — BNG habitat targets are usually met by the wildflower diversity and management regime, not by the format. See our Biodiversity Net Gain guide for more on meeting habitat metrics.

Is 80/20 by weight or by seed count?

By weight. Wildflower seed is far lighter and smaller than grass seed, so 20% by weight still delivers a meaningful number of wildflower seeds per square metre.

How much seed do I actually need for my area?

80/20 mixes are sown at 5g per m², 100% mixes at 3g per m². Use our seed coverage calculator to work out the quantity and nearest pack size for your area.

Can I add a 100% mix to an 80/20 meadow later to boost the flowers?

Yes, provided you open up the sward first (cut hard and scarify) so the extra seed can reach bare soil — oversowing straight into a closed grass canopy rarely works, whichever format you use.

Not sure which format or habitat mix fits your site? Email paul@wildahome.co.uk or call 0333 242 0602 with your soil type, location and area, and we’ll point you to the right one.

Related reading: Bespoke Wildflower Seed Mixes for choosing a custom balance beyond standard 80/20 or 100% ratios, and Choosing Wildflower Seeds for Hotter and Drier UK Summers if resilience to drought is a bigger factor for your site than format.