Many people associate lawn rollers with traditional gardening practices and think that rolling the lawn regularly is an essential part of maintaining a high-quality lawn.
But why were lawns rolled at all? Early lawns were cut with scythes (the first lawn-mower was invented in 1830). So they had no heavy equipment running over them. As well, there were no specially-bred turf grasses, and since finer grasses tolerate trampling better, heavy rolling tended to encourage finer grasses at the expense of coarser ones, giving a more attractive surface.
Today, especially if you use a cylinder mower, your lawn is lightly rolled every time it is cut. Plant breeders have provided us with fine grasses which we can encourage with over-seeding, fertilizing and close mowing.
So what benefits are there in rolling?
After frost, aeration or if there is a lot of earthworm activity, the surface of the lawn may be a little irregular. Rolling with a medium-weight roller will reduce those imperfections.
However rolling will compress the top few centimetres only and will not remove deeper irregularities.
If the layers of the lawn were not evenly compacted during preparation, or if stumps were left in which ultimately rot and collapse, then those problems will not be removed by rolling. Indeed, attempting to do so with a heavy roller may just introduce new problems.
If you have sunken areas in the lawn there are two ways to deal with them. Gradual top-dressing, adding only a couple of centimetres of soil at a time, will fill hollows eventually. The best approach is to remove the sod, fill the hollow, firm the soil well and re-lay the sod. This will fix the problem immediately. If you have buried stumps it is better to make the effort to remove them, (much easier now they are partly rotted) fill the space with soil and re-sod.
You should also consider your soil-type. If you have a rather sandy soil, rolling will do no harm. If you have clay, however, frequent rolling will damage the soil-structure and restrict air-flow into the soil, reducing root growth. It may also cause surface pooling of water which leads to further oxygen-deprivation of the root system.
If you do roll a clay soil, do it when the soil is dry as the structure is more stable at that time and is therefore harder to damage.
A roller is, however, a very useful tool when preparing and seeding a lawn. Frequent rolling as you level and prepare the seed bed will give you an even amount of compaction across the whole lawn surface, greatly reducing the chance of developing sunken areas later.
As well, after spreading seed, a roller is the best way to press the seed into the soil and establishing an intimate contact between the seed and the soil. This helps to keep the seed from drying out and is better and easier than trying to cover the seed with a thin layer of soil. How often do we see the best seed germination in the accidental footprints on a surface that has been left too loose and soft?
So if you are preparing a new lawn or want to roll your lawn to remove those surface irregularities, that old concrete roller is not what you need.
A modern, light-weight roller which fills with water is a much better choice. When empty it is easy to move around and can even be hung on the wall of a shed. It can be filled with any amount of water to adjust the weight depending on your needs or your soil-type. Sand can also be used as a filler, but the extra weight that gives will rarely be necessary.
If you play a lot of lawn games, like croquet or bowls, or if you use your lawn to practice putting, then you will need to fill the roller and use it regularly, as these games require a hard surface.
If you don’t have a cylinder mower a roller can even be used to fake those coveted lawn stripes, although you would do better to invest in a cylinder mower that will also give you a fantastic close cut, a gently roll every time you mow AND produce those stripes!