Grass is Useful Stuff!

Mulched Potatoes Sarpo Mira

Grass Clippings Mulched Potatoes (Sarpo Mira)

The grass is growing fast, plenty of water in the ground and a bit of sunshine really pushes it on. We’ve been mowing and the clippings are proving very useful.

Mulching Comfrey

I have topped up the mulch around the comfrey in the side field. The comfrey is doing much better this year since I started mulching it to reduce competition from the grass that was swamping it.

Normally comfrey just swamps out any weeds but with the very poor soil quality here it has had trouble getting properly established. Hopefully now it will have the strength to get its roots down and really take off. It’s such a beneficial herb for feeding the crops.

Grass Mulched Redcurrant Bush

Grass Mulched Redcurrant Bush

Grass Mulching Under Fruit Bushes

More grass clippings went around the fruit bushes on top of cardboard. Not only does this stop weed growth but it improves the soil underneath, encouraging worms and adding humus. It’s surprising how much just a layer of clippings will improve the soil.

Grass Mulching Potatoes

Yet more clippings went on top of the straw over the potatoes. I used to think of grass clippings as just being a problem. They’ve a tendency to clump in compost heaps unless well mixed with ‘browns’ like shredded cardboard. Now I’m using them as a weed suppressant and humus additive to the soil, even with a field to mow I could use more.

I’ve noticed that the mulch also helps keep the soil moist in hot, dry weather, the rain soaks through OK when it comes.

Note: Do not use clippings as a mulch if the grass has gone to seed or you’ll have grass growing where you don’t want it.

Generally gardeners would be happy if their lawns stopped growing and saved them the task of mowing but since I’m putting the clippings to good use I’m looking to increase the yield.

Growing Grass as a Crop

Ideal Height for Mowing Grass Pasture

grass growth rates

Cutting grass too short or too long reduces growth

The thing with grass is that when cut or grazed to a low level it allows some of the now unneeded roots to die back. This does have a benefit as those roots rot down providing humus to the soil. As it recovers, it produces some more roots and then the rate of growth increases until it reaches maturity. Then it stops growing and puts its energy into making seed.

There’s conflicting information on the ideal height, which varies according to the grass species anyway. I’ve seen anything between 2cm which is very short and 15cm which is quite long quoted.

In any case, if I let the grass grow too tall mowing becomes difficult as it clogs the blades and collection system. In practice I try to take a pass with the mower on the highest setting of 8cm when the grass is around 10 to 12cm high and, if I can, a second pass on the height setting below a few hours later or the next day. This collects the maximum amount of clippings with the least effort.

If the grass gets very long, perhaps because of rainy weather, I can cut tall grass using the mower’s side discharge system but then I have to rake the clippings up which are deposited in rows. This is very time consuming.

How Often to Cut the Grass

Periods between cuts vary depending on the season and weather conditions. Grass doesn’t grow when it’s below 5ºC and growth is slowed or even stopped when water is in short supply. With the long growing season we enjoy, growth can be nearly year round in some years and a cut in December if it’s dry enough is common. In the spring and autumn every fortnight is about right but in the summer it can need cutting every week.

Further Improving the Grass

The next stage will be to improve the quantity of grass by scarifying to remove the moss and thatch followed by liming in the autumn to increase the pH. Grass, like our veggies, grows best on soils with a pH level between 6.0 and 6.5. Most of our land is basically acid with a pH between 5.0 and 5.5.

In the spring I’ll follow up with a light application of a general fertiliser like Growmore at 70g/M2 and additional potash from wood ash (and possibly some sulphate of potash) which I know is very lacking. The potash will encourage clover that will fix nitrogen into the soil which will, in turn, fuel grass growth.

Note: Diagram adapted from one on Grass Fed Solutions web site (about low-cost pasture-based cattle farming)

Posted in Allotment Garden Diary
5 comments on “Grass is Useful Stuff!
  1. Sian Kealy says:

    I have used grass clippings this year to mulch my potatoes and raspberries. Earlier in the year I put the grass down to protect the potato plant from frost, then instead of earthing up I continued to use grass instead. It kept weeds down and the potatoes have been easier to harvest. The raspberries are still to be harvested in autumn but seem to be putting a lot of flower on.

  2. Jane Burnham says:

    Just a word of warning. I once used grass clippings early in the season to protect from threatened frost. I subsequently earthed up over the clippings and ended up with both clippings and potatoes rotting underground. Otherwise, with a tiny lawn and three allotments I definitely can’t get enough!

  3. john y says:

    are grass cuttings from greens and the fairways from from golf courses advisable for using on the allotment compost heap.

  4. Linda Ashton says:

    This is all good useful information
    Thank you

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