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How to water (timing, amount, method)
I'm moving from New Jersey, the Garden State, to California. In New Jersey I only had to water during dry spells every couple of years because of frequent rains and the humid climate. It's a different story in California.

Watering depends a host of factors, including things like soil type, sunlight/shade, plant type and regional climate (humidity, wind).
Other factors are:

  • Where is the plant, container or soil?
    Most container plants need watering on a daily basis in hot, dry conditions
  • How well established and what size is the plant, seedling or mature with deep roots.

Two key rules are:

  • Irrigate deeply and infrequently. Plant roots need air as well as water, so let the water soak in so the plants don't drown.
    For lawns and annuals concentrate their roots in the top 6" of soil; for perennials, shrubs and trees, it's the top 12".
    Watering deeply encourages deep roots to make the plant more drought tolerant.
    There are planter boxes which allow you to water from the bottom.
  • Water in the morning. If you do get moisture on the leaves, this gives them time to dry out. It's much more difficult for plant diseases to get a foothold when the foliage is dry.
    Late afternoon is the second best time.
How Much Water Do Vegetables Need? A good general guideline is an inch of water per week, either by rain or watering; in arid climates, it is double that. In hot weather, vegetables need even more water, up to about 1/2 inch per week extra for every 10 degrees that the average temperature is above 60 degrees.
Squash, eggplant, tomatoes, and other crops with large leaves need more than 1 inch a week.

evapotranspiration (ET) is the release of water to the atmosphere either thru evaporation from the soil or leaves where water taken in by the roots and and used for metabolic and physiologic functions is transported to the leaves.

There sensors like the Hunter WSS - Wireless Solar Sync that continually gathers on-site solar and temperature data used in the calculation of evapotranspiration (ET), then determine watering requirements.

Methods - Water Conservation:
Soaker hoses and drip systems save water because there is less evaporation with them.

See also:
Watering timers
Evapotranspiration - The Water Cycle, from USGS Water-Science School
How Often Should Tomato Plants Be Watered? | Home Guides | SF Gate
Vegetable Watering table | The Old Farmer's Almanac

Aside: When I googled "How frequently to water" the 3rd hit was "How often do I water marijuana plants? at Grow Weed Easy." Welcome to California.


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last updated 1 May 2017