Over time, the soil beneath your lawn will move and settle, leaving you with hills, hollows and undulations. Here are my tips on how to level a lumpy lawn.
To get that perfect bowling-green look, the surface of your lawn must be smooth. Doesn’t matter if it slopes slightly to help with drainage, but it must be free from lumps and bumps.
You’ll find too, that a lumpy lawn can lead to all sorts of problems with mowing. The hillocks are more likely to be scalped by the mower. Not only will this blunt your blades, it opens up the sward to let in weeds and diseases.
In contrast, dips in the lawn become obvious when the grass within them is slightly longer than the rest of the lawn. There’s a noticeable difference in colour.
Why is my lawn uneven?
Soil is amazing! Within the relatively small area of a domestic lawn there can be several areas with different soil types. Maybe there’s a mineral seam running through the lawn, or an old river bed. Perhaps parts of the lawn have been used for different things in the past. One of my customers has grassed over her old vegetable garden – but in certain weather conditions you can still see where they were.
If you’ve ever watched the TV program Time Team you’ll know that the soil in a garden (or a field) can give us clues as to what was there hundreds of years ago. So maybe the dips in your lawn are a hint that there’s treasure beneath it……you never know!
Dealing with gentle undulations
It’s perfectly normal for a lawn to develop gentle undulations over time. Especially if there are tree roots running underneath it or if one area gets more use than another. The simplest way of levelling out dips is to topdress with a very fine sand.
What is topdressing?
Topdressing is something that is carried out regularly by the best golf clubs and bowling greens. The greenkeepers apply a thin layer of finely graded sand or soil to the top of the grass and work it down towards the roots. The main purpose of it in this context is to create the perfect playing surface. But it can also help to control thatch, weeds and diseases.
For a domestic lawn, topdressing is the perfect way to smooth out the surface of your lawn without going to the trouble of lifting it or returfing.
Simply distribute the topdressing material around your lawn then work it into the sward using a broom or the back of your rake. You could even use a blower provided it’s switched onto its lowest setting (you don’t want to create a sandstorm!).
Watch my video to see how it works
A word about topdressing materials
If you are trying to level out a lumpy lawn, I always recommend using USGA topdressing sand. It’s not cheap but it does a grand job and rarely causes complications. Topdressing with builder’s sand is a no-no. It’s nasty sticky stuff that will stain your clothes and probably leave stones on the surface of the lawn. It’ll crucify your mower blades too.
Topdressing with a sand-soil mix is something that needs great care. You’ll find it described in many a lawncare book but in reality, it’s not as practical as they make it sound. Greenkeepers prefer to use an inert substance – like the USGA sand I’m using in the video. Introducing soil from an unknown source can also bring in weed seeds. If you are planning on re-seeding after topdressing, use a really good quality sand-soil mix from a reputable supplier.
- Topdressing is best done between March and October – when the grass is actively growing
- Choose a dry day
- Never topdress a lawn that is frozen or waterlogged
- Choose topdressing materials wisely
- Time your topdressing so that it doesn’t interfere with other lawn treatments. Ideally fit it mid-way between scarification or aeration treatments
- Avoid topdressing when your lumpy lawn is stressed by drought or disease
- Do not bury the grass completely. You should be able to see grass blades sticking up above the topdressing.
For more extreme lumps and bumps
Gentle dips are easily smoothed out using the technique in my video. Big bulges or deeper holes need a different approach.
Filling big dips in your lumpy lawn
For holes in the lawn, my advice would be to use a sharp knife of a lawn edger to remove the turf. Make sure you have a good 2-3 cm of soil on the back of your turf and set it to one side. Fill the hole with soil from elsewhere in the garden. If you use imported topsoil you’ll find that the grass will always look different where you’ve made the repair. Be sure to press the new topsoil down firmly. You don’t want it to settle and sink in the next few weeks!
Replace the turf carefully, ensuring that it is nice and level. Keep it well watered for 3-4 weeks while the grasses regrow their roots.
Getting rid of lawn lumps
Subtle lawn lumps can be rectified by topdressing around them. The big bumps that catch on the bottom of your mower call for bigger interventions.
Take a very sharp knife and cut a huge “H” shape in the lawn. The up and down lines of your H should run either side of the bump, the crossbar needs to be right across the middle of it.
You’ve created two flaps, starting in the middle of the bump, peel each flap backwards. Use your knife (or a sharp spade) to sever the grass roots but leave as much soil as possible attached to each “turf”.
Remove excess soil and check the level. Return the flaps of turf to their original position, and but the edges up together. You may need to trim them to fit. Water well and keep the soil moist until the grass has rooted back in.
To check for rooting, tug on the plants. If the whole sod lifts up, the roots aren’t quite ready for you to stop watering. If you get a handful of grass, your work is complete.
For lawn care help and advice
I have a comprehensive library of lawn care videos on my YouTube Channel and I’m very happy to answer any questions and comments you add to them.