Autumn & Winter Lawn Feed

Feeding a lawn in autumn

Autumn feeding is a different job from spring feeding, and the difference is the nitrogen. Through spring and summer you are asking a lawn to grow: nitrogen drives the leaf, and a high-nitrogen feed is the right tool. From late summer onwards you are asking it to survive — to harden off, hold colour through cold weather and come through winter with its roots intact. Nitrogen applied late produces soft, sappy growth that goes into the first frosts unhardened, which is the opposite of what you want. Potassium is what matters instead: it thickens cell walls, improves cold tolerance and helps the plant regulate water. That is why a proper autumn feed is low in nitrogen and high in potash, and why our high-nitrogen Lawn Fertiliser is not in this collection. It belongs in spring.

The potassium and magnesium

Sulphate of Potash is the straightforward answer: chloride-free potassium with no nitrogen attached, so it does the hardening job without pushing growth. Kieserite supplies magnesium as magnesium sulphate. Magnesium sits at the centre of the chlorophyll molecule, and lawns short of it go pale and yellow between the veins of the older blades first — a common sight on sandy soils and on lawns that have had years of high-potassium feeding without magnesium to balance it. Seaweed Extract Powder is the optional extra, watered on through the autumn.

Winter-wet, compacted and puddling lawns

Most British lawns fail in winter for structural reasons rather than nutritional ones. Water sits on the surface, air cannot reach the roots, and the ground compacts under foot traffic until nothing drains. Three products address that directly.

• Liquid Gypsum. Micronised calcium sulphate in suspension. The calcium helps clay particles flocculate into crumbs so water can move through, and because gypsum is a neutral salt it does this without shifting soil pH. Watered on, so it works on established turf you cannot dig.
• Granulated Gypsum. The slower granular form, for autumn top-dressing and for lawns being renovated or reseeded.
• Natural Wetting Agent. Made with soap nuts and aloe vera. It lowers the surface tension of water so it enters the soil rather than beading and running off. Adds no nutrients; it simply gets the water in and, on a lawn that puddles in one corner and stays bone dry in another, that is the first job.

Soil life and structure over the long run

Humic Acid Flakes dissolve completely and can go on through a hose-end feeder or watering can. Slow Release Humic Acid is the granular leonardite humate for autumn top-dressing, where it releases over months rather than weeks. Both help hold nutrients in a form roots can reach and support the soil biology that binds a rootzone together. Neither is a quick fix and we would not sell them as one.

Lime, and when not to use it

Sea Shell Meal and Garden Calcium Carbonate both raise soil pH and add calcium. Use them only if a test shows your lawn is genuinely acid. Guessing is how people end up with a lawn at pH 7.5 where iron and manganese lock up and the grass goes yellow for a completely different reason. A soil test kit costs a few pounds and settles it.

Common questions

When should I apply an autumn feed?

September into October for most of the UK, while there is still enough soil warmth for the grass to take the nutrients up. The further north you are, the earlier. Later than the end of October and you are mostly feeding the following spring.

Will any of this deal with moss?

No, and we will not pretend otherwise — none of these products is a moss treatment. What they do address are the conditions moss favours: compacted ground, water sitting on the surface, poor drainage and, sometimes, acidity. Fix the drainage and the compaction and you change the environment moss is thriving in. That is a slower answer than a moss treatment and a more durable one.

Can I use the spring lawn feed in autumn at a lower rate?

Better not to. Halving a high-nitrogen feed still puts nitrogen down at the wrong time of year; it just puts less of it. The ratio is the point, not the quantity.

My lawn is on heavy clay. Where do I start?

Liquid gypsum and the wetting agent, before anything else. Feeding a lawn that cannot drain is money spent on the wrong problem. The full set of clay amendments is in clay soil improvers.

Everything else for the lawn, including the spring and summer feeds, is in lawn care.