The benefits of covering soil with plastic

By Andrew Collyer - Practical Gardening

Published 12/03/2016 | 00:00

Andrew Collyer.
Andrew Collyer.

Feed fruit trees and bushes with potash.

Mahonia eurybracteata 'Soft Caress'

A couple of weeks ago I wrote about how covering an area of your vegetable garden with a plastic sheet might be a good idea. This was with the view that it would be uncovered and recovered according to the weather conditions allowing it to warm up quicker and dry out faster. This is looking like being an even better piece of advice than I had anticipated.

Having inspected, at home, an area of covered vegetable bed and comparing it with the rest of the vegetable garden, the latter is resembling something more like vegetable soup than a vegetable bed. Despite a reasonably dry week last week, Friday night and Monday have set back to square one any hopes of your garden soil drying out.

Vegetable areas can often be worse than ornamental beds as they are necessarily frequently dug over allowing air pockets to form in the soil which in turn fill up with water when it rains. This can turn the ground into litterally bog like conditions.

The benefits of soil covering have been such that I'm going to cover a second bed with plastic sheet. Heavy gauge plastic suitable for this is available readily in hardware shops and builders merchants and once you have it you can store it and reuse for many years to come. It tends to be black or green but I have occasionally come across clear rolls. A local polytunnel supplier might also supply you with a small quantity of poly tunnel plastic which would work perfectly.

The fact that it is clear does allow you to leave emerging plants covered for a little longer than with opaque plastic. But beware even if you have seeds sown under clear plastic and if it is not ventilated often mould and botrytis will soon put pay to your seedlings. This is known as damping off.

So realistically unless you are creating a framework for the plastic to sit on clear of the soil, and you can actually buy these units known as row covers, you will have to check daily for any seed germination then leave uncovered once this has happened. You will benefit from faster germination times though. Another hazard to be aware of is slugs and snails, but when arn't they a hazard, so be prepared with a supply of slug pellets or your chosen method of combat.

Peas, broad beans, onions, lettuce and beetroot can all be started now this way from seed. Onion and shallot sets along with garlic cloves are also suitable for getting started under plastic.

I am covering a second area with the intention of starting some first early potatoes [Sharpe's Express] under the plastic sheet in mid March. I will wait until there is some above ground growth showing before I remove the plastic. Even then I will keep it close at hand as during darkness if the temperatures drop I can recover until dawn.

I am hoping this method will gain me up to three weeks in getting my first early potatoes up and harvested. This is great news as not only can I be enjoying early crops but it will allow me to stagger my supply over a longer harvesting time. So no glut periods.

In the area I covered earlier I will plant onion and shallot sets this week. I will then recover with my clear plastic and after a week keep a daily check on them. Even if your plastic is opaque you can cover for a few days then uncover by day and recover by night until the sprout.

It will probably take the sets two weeks to show good sprouting and then I will remove the plastic probably for good unless we have a severe frost forecast. It is unlikely to kill off new shoots but could certainly be detrimental to them.

Wexford People

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