When to Fertilise Your Lawn in Hamilton (and What to Buy)

Walk down any street in Hamilton in November and you can pick the lawns that get fed. Same grass, same rain, same mowing. One is thick and deep green right to the fence. The one next door is pale, thin and full of clover. Most of the time the difference is two or three bags of lawn fertiliser a year, put on at the right time.

Most of the advice online is written for Australia or the northern hemisphere, so the months are wrong for the Waikato. Here’s when to fertilise a lawn in Hamilton, what to buy, and how to spread it without burning stripes into the grass.

The Short Answer

• Late September: the first feed, once the grass is clearly growing. Not before.
• End of November: a lighter feed to carry the colour through summer. That’s now.
• March: the autumn feed, after the first decent rain.
• Never in the cold of winter, and never on a lawn that has gone brown in a dry spell.
• Always water it in, the same day or just before light rain.

When to Fertilise, Month by Month

This is for a normal Hamilton lawn, which is mostly ryegrass with a bit of everything else mixed in. If yours is kikuyu, read the section further down.

The full year, with mowing, seed and weeds as well, is in the Waikato lawn care calendar.

Is It Too Late to Feed the Lawn in November?

No. November is one of the right times, as long as you go lighter than the spring feed. The grass is growing flat out right now, so the lawn uses what you give it.

What you don’t want is a heavy dose of nitrogen right now. It gives you a fortnight of soft, fast growth, more mowing while the lawn is already putting up seed heads, and nothing to show for it by Christmas. Light feed, watered in, then leave it alone until March.

Which Lawn Fertiliser to Buy in NZ

Mitre 10, Bunnings and Farmlands all have a wall of lawn food. It mostly comes down to four types.

• Slow-release lawn fertiliser (granules). The easy one. It feeds the lawn over several weeks, so it’s hard to overdo and you only need it two or three times a year. Best pick for most people.
• Quick-release lawn food (granules). Cheaper, greens up fast, but runs out sooner and is easier to burn the lawn with. Fine if you are careful with the rate.
• Liquid lawn food. Clips onto the hose. Very fast colour, very even, but it only lasts a few weeks. Good for a small lawn or a quick green-up before visitors.
• Weed and feed. Fertiliser with a broadleaf weed killer mixed in. Only worth it if the lawn has clover, catsear or similar weeds. If it doesn’t, you are paying for weed killer you don’t need.

Whatever you pick, make sure the bag says it’s for lawns. Lawns need mostly nitrogen. A general garden fertiliser has much more of the stuff that makes flowers and fruit, which grass doesn’t need.

Weed and Feed: When to Use It

Weed and feed works best in spring, when the weeds are growing hard and take the chemical in fast. In Hamilton that’s October into November. Autumn works too.

• Put the granules on a lawn that is damp from dew or a light shower, so they stick to the weed leaves.
• Don’t mow for a few days before or after. The weeds need leaf to take it in.
• Don’t water it in straight away like a normal fertiliser. Follow the bag for how long to wait.
• Not on a newly sown lawn. Check the label for how long to wait.
• Got clover or prickle weed? Those posts have the full fix.

How to Spread Lawn Fertiliser

1. Mow first. A day or two before you feed. Then leave a few days after feeding before the next mow, so the catcher doesn’t pick the granules back up.
2. Pick a dry lawn. Granules stick to wet grass blades and scorch them. Weed and feed is the exception.
3. Use a spreader. Throwing it by hand leaves dark green stripes and pale gaps, the classic patchy lawn. A cheap push or hand-held spreader does it evenly.
4. Half one way, half across. Set the spreader to half the rate, go up and down the lawn, then do the other half going side to side. No missed strips.
5. Stick to the rate on the bag. More is not better. Too much nitrogen burns grass the same way dog wee does.
6. Water it in. The same day, or put it on just before light rain is forecast. Not before a downpour, which washes it into the drains.
7. Sweep the paths. Blow or sweep stray granules off the driveway and footpath back onto the lawn. Some lawn foods with iron in them stain concrete, and anything left on the path ends up in the stormwater.
8. Keep kids and dogs off until it has been watered in. The bag says how long.

Signs Your Lawn Needs Feeding

• A pale, yellowy-green colour in spring when the lawns around it are deep green.
• Thin grass you can see soil through.
• Clover taking over. Clover makes its own nitrogen, so it moves into lawns that never get fed.
• Slow growth in October and November, when every other lawn in the street needs mowing weekly.

Before you buy a bag, rule out two other causes of a yellow lawn. Mowing too low is the most common one, so check your mowing height. And if a brown patch lifts up like carpet, it’s grass grub, not hunger. Fertiliser won’t fix either.

What About a Kikuyu Lawn?

Kikuyu runs on a different clock. It grows in the heat and goes dormant and straw-coloured from about June. Feed it while it’s growing, from late spring through summer, as long as it isn’t drying out. No amount of fertiliser in winter will wake it up. Not sure which grass you have? See kikuyu or ryegrass.

Frequently Asked Questions

When should I fertilise my lawn in Hamilton?

Three times a year suits most Hamilton lawns: the first feed in the last week of September once the grass is clearly growing, a light feed at the end of November, and an autumn feed in March after the first decent rain. Don’t feed in winter, and don’t feed a lawn that has gone brown from dryness.

Is it too late to fertilise my lawn in November?

No. A light feed at the end of November carries the colour through summer. Go lighter than the spring feed and water it in. Once the lawn starts drying out in December or January, stop until autumn.

Should I fertilise my lawn before or after rain?

Just before light rain is ideal, because the rain washes the granules down to the roots. Avoid putting it on before a heavy downpour, which can wash it onto paths and into the drains. If no rain is coming, water it in yourself the same day.

Should I mow before or after fertilising?

Mow first, then feed a day or two later on a dry lawn. Water it in, and leave a few days before the next mow so the catcher doesn’t pick the granules back up.

What is the best lawn fertiliser in NZ?

There isn’t one best bag. For a Hamilton lawn, buy a fertiliser made for lawns, which is mostly nitrogen. Slow-release granules are the easy option if you only want to feed two or three times a year. Liquid lawn food gives a fast green-up but doesn’t last. Weed and feed is only worth it if you have broadleaf weeds like clover or catsear.

Can fertiliser burn my lawn?

Yes. Too much in one spot, fertiliser spread on a hot dry lawn, or granules that aren’t watered in all scorch the grass yellow then brown. Use the rate on the bag, spread it evenly with a spreader and water it in.

Happy mowing!