What the area has to tolerate - traffic, shade, drought, mowing height - rather than seed quality.

Hard-wearing mixtures are coarser and recover from damage.

Fine ornamental mixtures look better and will not take footfall.

Shade-tolerant mixtures exist because standard blends fail under trees.

Drought-tolerant and low-maintenance mixtures trade appearance for less watering and mowing.

A mixture chosen for the wrong conditions fails however well it is sown.

The existing sward competes with the seed, so seed-to-soil contact is the whole problem.

Broadcasting onto uncut, unprepared turf achieves very little.

Scarifying or aerating first is what makes it work.

Cutting short beforehand reduces competition for light.

Top-dressing after sowing improves contact and protects the seed.

New establishment is far simpler: prepare a seedbed, sow, keep it moist.

By soil temperature rather than the calendar - late summer and early autumn is usually better than spring.

Seed sown into cold soil sits and rots or is eaten.

The same seed weeks later into warm soil germinates quickly and outgrows the weeds.

Autumn offers warm soil, reliable moisture and less weed competition.

Spring sowing works but faces both weed competition and the risk of a dry early summer.

Local climate shifts the windows considerably, so the principle rather than the month is what transfers.

Moisture - seed that germinates and then dries out is dead.

The soil surface is exactly where it dries first.

Little and often is the requirement until establishment.

A single missed period in warm weather can lose a whole sowing.

Light top-dressing or a covering helps retain surface moisture.

Traffic must be kept off until the sward has established, which takes longer than people expect.

Viability declines in storage, and faster in warm damp conditions.

Part bags kept for several years germinate poorly.

Cool dry storage in a sealed container slows the decline.

Sowing old seed at a higher rate partly compensates and is not reliable.

Buying to the season rather than to the discount is the simpler answer.

Germination test information on the packaging indicates what the seed was when it left the supplier.

Coatings can improve moisture retention and deter birds, at the cost of fewer seeds per kilogram.

Coating adds weight that is not seed, so rates differ from bare seed.

Some coatings carry fertiliser or fungicide to aid establishment.

Availability of treated seed differs between markets under pesticide regulation.

Bird predation is a real loss on open sowings and coatings help with it.

Comparing prices requires comparing seed content rather than bag weight.

Considerable - within a species, cultivars differ in wear tolerance, disease resistance and appearance.

Independent cultivar trial data is published in several markets.

Named cultivar mixtures state what is in them; generic mixtures often do not.

A cheap mixture may be species-correct and cultivar-poor.

For sports and high-specification turf, cultivar choice is a serious decision.

For a general domestic lawn the species blend matters far more than the cultivars within it.