What Distance Between Holes When I Aerate Lawn?

Q.I intend to aerate my lawn using a ‘hollow tine’ tool, but would like advice on the distance between holes etc. We live on an area that has been reclaimed from use as a quarry, and the lawn is no more than 12 inches above a compacted layer of clay. The Lawn was laid about a year ago and appears to be very wet, though not waterlogged.

(R.S, 13 March 2009)

A.Yours is an interesting question – principally because it raises a whole lot of other issues beyond simply the distance between the holes!

You don’t say what type of soil your garden has above the clay layer and this is important in terms of your choice of aerating tool. Hollow tine aerators are great for heavy soils – they pull a core of soil out with them, which leaves good, wide channels for air to circulate – but they shouldn’t be used on sandy soils.

Assuming that this is the appropriate tool for your type of ground, the usual advice would be to make the “spiked” rows the same distance apart as the tines are from each other, to produce an even pattern of holes across the surface. I’m not clear from your question whether you intend doing the whole lawn – or, indeed, how big a patch of grass we’re talking about – but in general terms, you’d normally only expect to aerate actual problem areas, rather than the whole lawn, unless it’s a very small one.

Aerate Or Drain?

It’s difficult to be sure without seeing your site, but I’m tempted to ask why you’re thinking of aerating in the first place. Aeration is generally used to break the compacted layer that typically forms in the top three inches or so of a lawn when soil particles have been squeezed together – typically after very heavy use of the lawn, or the passage of time. Your lawn is only a year or so old – which makes this kind of natural near-surface compaction very unlikely.

What worries me about the situation you describe is that with compacted clay so near to the surface, I’m not at all sure that aeration is going to make any difference. As I said before, it’s always difficult to make too strong a diagnosis without actually being able to see things for yourself, but it seems to me that there’s a very good case for making a serious improvement to the drainage – or else it sounds like you’re always going to run the risk of having a fairly boggy lawn, with all the problems that entails.

Laying full drainage, usually a series of clay pipes in gravel filled trenches, is not often worth the cost and upheaval, but there’s pretty broad agreement that it’s the best approach for sites with impermeable clay subsoil – and often the only real hope of success. I honestly think that before you spend too much time and money on aerating or trying any other “surface” remedy, you’d probably be best advised to get a local land drainage adviser in to have a first-hand look at the problem.

I’m sorry to be the bearer of bad news, but if my suspicions are correct and you do get the right professional help at this point to sort out the drainage, you should end up with a lawn to be proud of – and be able to enjoy it for years to come. Good luck!

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