Tuesday 22 October 2019

Scorched lawns? Nature will heal it

If summer's heatwave killed your grass, let time and nature revive it, writes Gerry Daly

AFTER A DRY SPELL: It is from the tough resilient stems that new shoots and leaves are rapidly produced when rain falls.
AFTER A DRY SPELL: It is from the tough resilient stems that new shoots and leaves are rapidly produced when rain falls.

As expected, most lawns recovered very quickly from the severe damage done by the prolonged period of drought or near-drought. Grass in a lawn suffers most from drought damage because cut grass sward is only two or three centimetres deep. Nor does it have the shading effect that tall grass has. But, in any case, grass is especially well fitted to cope with drought.

The leaves of grass grow from a stem. When the pressure comes on a grass plant in a dry spell, growth slows down and eventually stops the production of leaves. The existing leaves have their water supply cut off and they shrivel, but still perform the useful function of shading the lower stems. Grass stems are relatively tough and have a better moisture-sealing skin. It is from the tough resilient stems that new shoots and leaves are rapidly produced when rain falls. Just a couple of days after a few heavy showers grass will have recovered.

But the quick recovery of grass over the last week or so is not just down to the rain. It got an extraordinary boost from natural nitrates produced in the soil by the decomposition of dead roots and other organic material. You might have noticed how green and lush the new grass appears and this was the boosting effects of plant nutrients that had been produced by high soil temperatures. The nitrates built up to exceptional levels as grass plants were not able to use them but there was no rain to wash them away. Nitrates knocked out of the air by lightning also contributed to the supply of natural nutrients.

However, not all lawns have recovered completely. In some parts, notably in the east, lawns are still short of moisture. Many lawns have patchy regrowth with some areas of grass not recovering at all. Shallow depth of soil, or gravelly shalely ground is the cause. It is most evident where areas have dried along kerbing, and it is not uncommon for builder's rubble to have been buried randomly with a shallow depth of soil spread over the rubble, and such a situation would allow dead patches to develop.

Whether your lawns have recovered or not, the natural initial boost is largely over and many lawns have slowed down now for the year.

Autumn lawn feed can be applied to continue the boost of growth, or on large lawns of more than 1,000 square metres, low-nitrogen farm fertilisers can be used as a cheaper alternative. An autumn lawn feed sets up the lawn for winter, alongside mowing regularly as necessary.

Patches of withered grass with no signs of growth will soon come under the influence of the next natural process, namely the germination of grass seeds shed previously.

However, along with self-sown grass seedling, weed seedlings will also emerge. This is one of the main ways that broad-leaved species, such as daisies, dandelions and clover get started against weak grass opposition.

This will be welcomed by those who grow a wildflower lawn and considered unwelcome by those who prefer a uniformly green lawn. Ruffling the soil surface with a rake and scattering some lawn seed will help the grass to compete with the broad-leaved lawn wild flowers. When mowing the lawn, avoid sown patches for a few weeks until the grass is growing well.


WALK IT: Looking for garden ideas? Take inspiration from the Dublin Garden Trail. Featuring 12 beautiful private gardens from Ardan in Howth in north Dublin to the Dower House in Ashford, Co Wicklow, all within striking distance of the M50. Trish Farrell, of Knockrose garden in Kilternan, promises: “A warm welcome awaits you in each of these beautiful gardens. Visitors go home energised and full of ideas for their own garden.” DublinGardens.com

PLANT IT: Agapanthus, the blue African lily, is the star of the show in many gardens at the moment, the blue flowers contrasting with so

much seasonal yellow. The sunny hot summer has suited it and it has responded accordingly. A good plant anywhere, it is even better in coastal gardens. From good garden centres nationwide.

POST IT: Four new €1 stamps designed by Dublin’s Design HQ, based on illustrations by botanical artist Shevaun Doherty, pay tribute to our native bumble bee, heather bee and rarer Tawny Mining and Ashy Mining bees. They are even hexagonal in shape. Also available at post offices, Dublin’s GPO and online at irishstamps. ie is a beautiful mini-sheet of the stamps and a

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