Watering vegetables
Apply water to the soil, not plants
How much to water depends on a number of variables:
- soil (clay, silt, sand),
- effect of wind,
- amount of organic material in the soil,
- whether a mulch has been applied
- and when it last rained!.
A good guide is to try to imagine your plant above ground mirrored by the root system below ground. Seedlings will require more watering than a tall plant that has an extensive root system. Alternatively, dig down a spades depth – the soil should not be dry.
Commercially, irrigation is used to maximise production – but most vegetables will crop adequately without much additional watering.
Water requirements
Requirements for watering vegetables varies depending on the crop, and growth stage. Leafy crops need more water than those grown for their fruits or roots. Seedlings will not recover if they dry out because of their small root system; water regularly in dry weather until established.
Drought tolerant once established
Onions, leeks, carrots, beetroot, sprouting broccoli, Brussels sprouts, winter cabbage, spring cabbage, winter cauliflower, parsnips, marrows, spinach beet, Jerusalem artichoke, parsnip, radishes, swede, turnips, chicory and endive.
Regular watering (only in dry weather)
Leafy crops may need regular watering in dry weather, particularly on light soils to encourage leaf growth.
Water after flowering (only in dry weather, if needed)
Peas
Beans (Runner beans need a lot more water than French beans)
Tomatoes
Squashes, Pumpkins and marrows (many will survive without much extra watering
unless you are trying to grow huge fruits)
Courgettes
Watering these crops before they start to flower will only encourage leafy
growth, without improving the crop.
Watering vegetables in containers
Do not allow container vegetables to go short
of water. In hot, dry weather a tomato plant may need watering twice a day
for instance. Rain can bounce
off leaves and doesn’t always get into the roots, so you might need
to water, even on rainy days.
Remember, the container grown vegetable (or any other plant) relies on
you completely to supply all its needs. Never let the plants dry out.
When to water
Apply directly to the soil either in early morning or evening, when the air and soil are cool (reduces loss to evaporation). Slug susceptible plants (leafy crops etc) should only be watered in the morning though, as slugs are not only nocturnal but will be more active if you wet the soil, thus creating ideal conditions.
Ways to conserve water:
Collect as much rain water as you can
- Mulch the soil surface. Materials like leafmould, grass clippings, newspaper, straw and composted bark chippings, will all help to reduce moisture loss and suppress weeds. Apply when the soil is moist and has warmed up and the plants are established. Water well if soil is dry before laying down the mulch.
- Remove weeds; they will be in competition for water resources with the plants/vegetables you want to grow.
- Windbreaks are good for sheltering plants from drying winds.
- Shade seedlings in hot weather.
- Water loss is increased by evaporation when digging in dry hot weather.
- Increase the water-holding capacity of the soil by digging in organic matter. Alternatively use organic matter as a mulch, reducing water run-off.
- Watering early morning and late afternoon will reduce evaporation rates.
- Apply water to the soil, not plants.
- Collect as much rainwater as possible by using water butts.
- Overwatering has more of a detrimental affect on plants. It will also encourage the roots to search in the top few centimetres of the soil, thus discouraging roots from searching deeper into the soil. Grow runner beans over a well prepared bean trench.
See also:
- Garden Organic Guidelines on Water use in the garden
- Water in the organic garden - factsheet
- Grow Your Own - What to do in your vegetable garden now
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