Lawn Feed Through the Year: What to Use and When

If there's one thing I've learned after years of poking at lawns with a soil probe and a spreader, it's that feeding grass isn't about chucking down whatever bag happens to be on the shelf. The single biggest mistake I see — and I made it myself for years — is using the wrong feed at the wrong time of year. A high-nitrogen spring feed flung onto a lawn in October will push out soft, sappy growth that frost murders within weeks. An autumn formula applied in May will leave your grass looking distinctly underwhelmed when it should be racing away.

So this guide isn't a single product review. It's a proper walk through the whole calendar, looking at what your lawn actually needs each season, which real products deliver it, and — crucially — how to read those three numbers on the bag (the NPK ratio) so you never get caught out again. I'll be referencing specific feeds I rate, including the Pro-Kleen Spring & Autumn range, Pro-Kleen Autumn Green, MycoGro's mycorrhizal blend, and the Proctors seasonal pair, with their real specifications throughout.

NPK Explained: The Three Numbers That Run the Show

Every bag of lawn feed carries three numbers, typically printed large on the front — something like 6-5-10 or 11-5-5. That's the NPK ratio, and once you understand it, choosing the right feed becomes genuinely straightforward. Whilst it looks like a code, it's really just a recipe ratio for three nutrients.

You'll also see "extras" beyond NPK — things like iron (often written as Fe, sometimes a percentage like "+6% Iron"), magnesium (MgO), and biological additions such as seaweed or mycorrhizal fungi. Iron is the one that catches people out: it greens grass up dramatically and, at higher rates, blackens moss so you can rake it out. It also happens to be the most common cause of staining on patios and the scorch we'll talk about shortly.

Spring Feeds: Waking the Lawn Up

Spring is the lawn's growth season, and the feed you reach for should reflect that. Spring lawn feeds are high in nitrogen, which promotes strong leaf growth to get the lawn into good shape for summer. This is also why feed-and-weed combination products — which are usually high in nitrogen — are best used in spring at the start of the growing season, when actively growing weeds take up the herbicide most effectively.

A textbook spring feed is the Proctors Spring & Summer Lawn Feed, with an NPK of 11-5-5. That dominant first number tells you immediately it's built for top growth and that classic lush green look. It comes in a mini-granular format that spreads easily and suits all lawn types and sizes, applied at a rate of 35g per square metre.

The Pro-Kleen Spring & Autumn Lawn Feed also covers the spring window, recommended for application in the January–March period (and again in autumn, which we'll come to). Its formulation is a more balanced 6-5-10 plus 6% iron in the 2.5kg tub, which makes it less of a pure growth-pusher than the Proctors and more of an all-rounder — that iron content gives an early-season green-up and helps tackle the moss that always seems worst after a long, damp winter.

Why nitrogen-forward works in spring

Through April and May the grass is hungry. It's recovering from winter wear, knitting together bare patches and building the density that crowds out weeds and moss. Nitrogen fuels that. The Proctors 11-5-5 ratio, with more than double the nitrogen of its phosphorus and potassium, is squarely designed for this push. Apply it as growth gets going and you set the lawn up for a strong, dense summer.

Autumn Feeds: Toughening Up for Winter

This is where the philosophy flips entirely. In autumn, lawn growth naturally slows, and the feed should accommodate that change with less emphasis on nitrogen (which would only push out vulnerable leafy growth) and more on the nutrients that strengthen roots and build hardiness. As Proctors rightly point out, many spring problems can be reduced simply by not ignoring autumn and winter feeding.

The standout illustration of this is the Proctors Autumn/Winter Lawn Feed at NPK 3-10-5. Look at those numbers: nitrogen knocked right back to 3, phosphorus pushed up to 10. That high phosphate is all about healthy roots, giving the lawn extra protection through the cold months without forcing the excess top growth that frost would damage. It's applied at the same convenient 35g per square metre as its spring sibling.

The Pro-Kleen Autumn Green Lawn Feed takes a slightly different route with an NPK of 10-5-10 +2MgO, applied August to October at 25–40g/m². The higher nitrogen here might surprise you for an autumn feed, but it's balanced with strong potassium and crucially blends fast and slow-release nitrogen — the fast portion gives a quick green boost as the season turns, while the slow-release feeds steadily. It's specifically formulated to protect against red thread, the pinkish fungal disease that loves autumn conditions, by strengthening each blade for disease resilience.

The Pro-Kleen Spring & Autumn Range in Detail

For gardeners who want a single product covering both shoulder seasons rather than buying two separate feeds, the Pro-Kleen Spring & Autumn Lawn Feed is the obvious candidate, and it's one I keep coming back to. It's designed for application across the September–January window as well as January–March, with balanced NPK to supply the nutrients needed during both spring and autumn periods.

There's a subtle but worth-noting difference between the two pack sizes. The 2.5kg tub runs an NPK of 6-5-10 plus 6% iron, while the larger 20kg bag shifts slightly to 6-5-11 with iron and seaweed. That seaweed addition in the bigger bag is a nice touch — seaweed extracts are well regarded for encouraging stronger, more resilient growth.

The standard application rate is 25–35g per square metre for regular feeding, stepping up to 40g per square metre if you're using the iron content to tackle unwanted growth such as moss. The fine 1–2mm granules are a genuinely practical detail — they settle into the sward and disappear from view quickly, rather than sitting on top looking like spilt cereal. The 2.5kg tub is slow-release lasting 4–6 weeks per application, while the 20kg bag is described as nourishing the lawn for up to three months.

MycoGro: The Biology-First Alternative

If your interest in lawn care extends beyond simply feeding the grass to feeding the soil, the MycoGro Spring & Autumn Lawn Fertiliser is a fascinating option. It's a premium slow-release feed enriched with mycorrhizal fungi and thatch-degrading microorganisms, specifically formulated to support lawns through the spring and autumn growth periods.

Its NPK is 5-2-10, enriched with 4% magnesium and 2% iron, and — unusually — it contains 50% organic matter. That high organic content, combined with the living additions, is what sets it apart. The mycorrhizal fungi colonise and extend the grass's root system, effectively increasing the reach of every root, while the thatch-eating microbes break down the dead grass layer that otherwise builds up and returns those nutrients to the soil.

It's applied at 25–50g per square metre, every six to eight weeks or as required, and comes in 10kg and 20kg bags. It suits fescue, closely mowed and standard lawns alike, and even works on fruiting and flowering plants — which makes it a versatile bag to have in the shed. It's used not just by domestic gardeners but on estates, in professional landscaping and on schools and local authority projects, which speaks to its consistency.

Head-to-Head: Comparing the Seasonal Feeds

Here's how the main contenders stack up side by side. I've lined them up by the metrics that actually matter when you're standing in the shed deciding what to spread.

And for the autumn/winter slot specifically, the contrast between the two dedicated autumn formulas is instructive:

Neither is "better" in absolute terms. The Proctors 3-10-5 is the purist's autumn/winter feed, almost entirely root and protection focused. The Pro-Kleen Autumn Green is more of an early-autumn green-up-and-protect feed, suiting the August–October window when there's still a bit of growth left in the season and red thread is a live threat.

How to Avoid Scorch — The Bit Everyone Gets Wrong

Scorch is the heartbreak of lawn feeding: those harsh yellow or brown stripes and patches that appear days after you've spread fertiliser, often tracing the exact path of your spreader. It happens because concentrated nutrients — particularly nitrogen and iron — draw moisture out of the grass blades when there isn't enough water around to dissolve and carry them into the soil. The result is, effectively, a chemical burn.

Here's my reliable, scorch-free routine, refined over plenty of trial and error:

Your Year-Round Feeding Calendar

Pulling it all together, here's the simple seasonal rhythm I follow. You don't need to feed monthly — a couple of well-timed applications in spring and autumn, using the right NPK each time, does the heavy lifting.

Spring (January–March into April–May): Reach for a nitrogen-forward feed. The Proctors 11-5-5 is the classic growth-pusher; the Pro-Kleen Spring & Autumn 6-5-10 with iron is a gentler all-rounder that also tackles spring moss. Apply onto damp grass or before rain.

Summer (June–August): The danger zone for scorch. The Pro-Kleen Spring & Autumn feed explicitly isn't recommended for summer. If you feed at all in summer, do it only with adequate moisture and never in a heatwave.

Autumn (August–October/November): Switch your thinking to roots and resilience. The Pro-Kleen Autumn Green (10-5-10 +2MgO) suits the August–October window with its red thread protection, while the Proctors Autumn/Winter 3-10-5 is ideal as the season deepens and you want minimal top growth.

Winter (September–December/January): The Pro-Kleen Spring & Autumn 20kg blend, with its iron and seaweed, is designed to nourish through this period for up to three months, encouraging resilience to falling temperatures and frost. Keep nitrogen low and don't feed onto frozen ground.

Who Should Buy Which Feed?

Overall Rating

Taking the seasonal feeding approach as a whole — and the Pro-Kleen Spring & Autumn range as the most versatile single recommendation within it — here's how I score things across the categories that matter.

Frequently Asked Questions