Reducing water use and effort spent watering

It’s a while yet, but soon you’ll have a bunch of thirsty vegetable plants on the plot, requiring your attention and just the right amount of water! Actually, if you remember, last spring was exceptionally dry: it was the driest since 1984, and 11th driest since 1910, so it probably pays to be ready!

Not only does saving water help prevent depletion of natural aquifers and water courses, and save you money (if you’ve got a meter), but rain-water is free of chlorine that can effect soil bacteria, and free of lime, which with our hard London water, can harm lime-hating plants (although most vegetables like a bit of lime).

Here’s a check-list:

  • Get a water-butt.
  • Improve your soil.
  • Mulch.
  • Use a drip-irrigation system.

Water butt tips

  • Buy the biggest one that you can afford/that fits the space; an overtopping small water butt in early summer is sure to be pretty empty by mid-summer!
  • If you can attach it to a down-pipe from your house’s roof using a diverter, all the better, but remember that even a small shed or greenhouse roof collects quite a lot of water; that’s where mine is, and it easily fills my 250l butt during a wet winter month.
  • Check if your council has teamed up with a supplier to provide cheaper equipment; for example Ealing has here: http://www.ealing.getcomposting.com/

A butt on a shed will collect a significant amount of water

Improving Your Soil

One of the best ways to reduce watering is to improve your soil. Although clay soils often seem soaked in winter, the small particles of the clay actually make it difficult for roots to extract water when things start drying out, and there are few gaps where water will be held after rain.

The best way of improving any soil is to add a lot of coarse organic material, such as (properly) composted wood-bark, horse manure and garden compost. Adding Sharp Horticultural Sand is also pretty good idea on clay, as the larger particles help provide space for water (avoid builders stuff, as it my contain salt).

Modern advice is not to dig the material in (e.g. by double-digging), just put it on top, and lightly fork it into the surface: worms and weather should do the rest (although the foxes are doing quite a good job of digging my compost in at the moment!).

Another thing you can do, before it’s warm enough to sow anything frost-intolerant outside, is to sow a fast-growing green manure. This is a plant that will put down roots, opening up the soil and bringing nutrients to the surface; it also covers the soil, stifling weeds and protecting it from being washed away or compacted by heavy rain, and provides some bulky organic material to dig in afterwards.

Mustard grown as green manure: the bed in the left has been cut and left to wilt before digging-in

This time of year, try Mustard or Fenugreek, which are both good on clay soil; after a few weeks of growth, but before they flower, cut the plants up using a hoe or sheers, leave them to wilt for a couple of days, and then either add them to the compost heap, or lightly dig them in. If you dig them in, leave a couple of weeks before sowing seeds, as they may inhibit germination (transplanting is fine though). You can also leave some of the crop to flower, which will feed the bees and hover-flys, and provide you with seed to collect and save for next year.

Mustard in Flower: the bees love it!

Mulching

A mulch is a material that you put on-top of soil to prevent it from drying out; it’s usually (but not always), an organic material such as wood-chips, straw or compost, or layers of cardboard or shredded paper. This material will eventually break-down to add humus to the soil, but in the mean time it stops the wind and sun from drying the surface of the soil, greatly reducing water-stress.

Make sure the soil is well wetted before applying it as it will be difficult for water to get down to the soil surface afterwards, and don’t put it right up against the stems of plants, or you may cause them to rot. You can water plants after applying the mulch (by watering at the stem of the plant), but the whole point is to avoid having to provide much extra water. Mulch also works well when put on-top of ‘leaky hose-pipe’-type drip irrigation systems.

Drip-irrigation

Although this may seem a high-tech solution, in my opinion, nothing is better at getting the right amount of water to the right place than drip-irrigation!

Systems range from perforated hose-pipes that you bury under mulch for watering larger beds and shrubs, to small dripper systems that take water to individual plants or pots. They’re also great for hanging baskets.

If you’ve mains water available in your garden, you can buy a hose-attachment and a timer (don’t get all gadgety, the simplest timer will probably do what you want, you don’t need an LCD display!).

If you’ve no mains-pressure water you can run a system from a water butt (if it’s either full-enough, or elevated enough), or what I did, which was install some high-level toughs, in my case, on top of the shed, fitted with water-butt taps, which I could keep manually topped-up with a couple of weeks of water. The main thing is that you have enough pressure to ensure that water reaches all the plants you want to water, and enough water to last for a couple of days, or however long you may need to leave them unattended.

My off-mains drip-irrigation system; a little heath-robinson, but it worked!

My extended system (pictured) did just over two weeks on 30 litres of water, drip-irrigating four strawberry plants, six tomato plants, a hanging basket with a cucumber in it, a fig tree, some mint and another hanging basket with bee-friendly flowers in it. But do replace the battery in the timer each season: don’t do what I did and come back after a week to find some rather droopy strawberries (fortunately this was a test before the tomatoes went in)!

A simple battery-powerd timer: you can set it for e.g. 5 minutes, twice a day

This year I may even get around to doing my proposed solar system, using the power of the sun to pump water from the water-butt into the troughs, rather than climbing a step-ladder with a watering can!

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