Watering -- When, How Much, and Methods

Last year's tomato bush fully branched and leafed out means high respiration rate and evaporation, so much more water is needed, especially above 90-95-degree days.

Lettuce roots are shallow, going down to maybe 1 foot.

Potato roots are shallow, going down to 1 foot.

Beans roots grow to a moderate 2 feet deep. These are from last year.

Carrot roots, depending on variety, can grow down only a couple of inches (great for clay soil) or to 2 feet (great for sandy soil).

Asparagus roots can grow down to 3 feet and need a lot of manure added each year to thrive up to 15 years.

Last year's Celebrity plant grew roots down to 3 feet.

Keep lavender and rosemary in a dry garden space away from other plants that want lots of water.

Hand-held hose with fine-spray wand fills 4-foot-wide basin of apricot tree. Also, pointed upward to wash undersides of foliage.

Hand-held hose with bubbler attachment fills basin of cauliflower plants.

Soaker hose strung around tangerine tree about 9" apart to beyond the drip line. Cover with mulch to lessen evaporation. But be careful if digging in the area so you don't puncture the hose!

5-gallon nursery containers with bottom holes buried almost up to their rims, leaving space for more mulch applied on top of the soil. Adding a small shovelful of manure or compost into the container provides manure tea or compost tea with every filling of the container.

   One of the more frequent questions beginning gardeners ask is “When do I water, and how much?    To which experienced gardeners respond, “It depends”.  Frustratingly unhelpful for everyone!  But, it’s true – it depends on many factors specific to each garden in each season, each plant and each gardener.  What extent of direct sun and shade does the garden get during each month of the year?  What kind of soil is in each garden, and are there different kinds in different places? What plants are growing, how deep are their root systems, and are they drought-tolerant or water-needy?  How attentive is the gardener – walking through the garden daily or weekly or only when there’s something to harvest? 
     Each of these elements balanced together provides a list of possible answers to that basic question of when and how much to water and what methods to use.  Now’s the time to fit these pieces together to get plants growing well as we move into our warm summer season.
 
When Do I Water?
   Frequency changes depending on the weather.  Mostly to this point, we’ve had a coolish spring, so that wonderful quantity of November and December rains that soaked into the soil has not evaporated beyond the surface inch-deep or so.  But, those couple of days of 90-degree air temperatures weeks ago, combined with the current high-80-degree temperatures means that established plants have begun actively growing and pulling moisture from the soil.  Which means that gardeners need to begin consistently replacing that moisture as the air warmth continues and new plants are added.
     A basic timing schedule for watering during each season is:

• Spring = Once every 3 weeks.  Soils are still cool, and roots are just beginning to actively grow.
• Summer = Once a week, with more according to the plants’ specific foliage bulk and respiration rate – like fully-branched-out tomatoes when air temperatures are above 90-95 degrees.  Above these temperatures, plants shut down to wait until cooler temperatures return, so more water will run the risk of drowning them.
• Fall = Once every 2 weeks.  Soil temperatures are still warm, but air temperatures and direct sun are lessened, so plant roots are more comfortable and growing.
• Winter = Once a month if there’s no rain. As cool as we get – perhaps into the low 40 degrees, plant roots basically go dormant and stop growing, so more watering than this will run the risk of drowning the plant.

     You may be surprised at how infrequent this schedule is.  But, it leads directly into our next element.    

How Deeply Do I Water?
    Watering depth stays the same year-round for each group of plants so their entire root zones remain evenly moist.  Each time you water, you apply enough water to reach each plant’s bottom-most roots.  This is why it’s important to grow together those plants that have similar root depths and moisture needs.

• Shallow – to 1-foot depth – carrot (depending on variety), celery, lettuce, onion, radish, potato
• Moderate – to 2-foot depth – bean, carrot (depending on variety), cucumber, eggplant, pepper, squash
• Deep – to 3-foot depth – asparagus, globe artichoke, melon, pumpkin, tomato

 

• Water needs of individual plants are another consideration when you plant.  For example, keep lavender and rosemary (which want little water) separate from basil and cilantro (which want more water). 

      When you water more frequently and not as deeply, as I’ve specified above, plant roots stay close to the surface since that’s as far down as the water goes.  When hot weather bakes the soil, these roots also get baked, and the plant dies or becomes so weak from heat stress that it succumbs to pests. 
     I used to have a neighbor that loved to sprinkle her garden every evening when she came home from work.  It gave her great pleasure to be in touch with her garden and its plants. This worked fine during the mild spring weather.  However, once the daily air temperatures rose above 85 and 90 degrees, her plants were perpetually droopy, even when she took to sprinkling everything before she left for work in the morning as well as when she returned home in the evening.  Within two weeks, the plants died – the shallow roots never had the relief of growing deeply into the cooler soil, and they rotted out due to drowning from being watered twice a day that pushed out all the air pores.

What’s Soil Got To Do With It?
   The soil in the garden determines how quickly water is absorbed and how widely it spreads underground.  Sandy soil drains quickly and mostly downward.  Clay soil is the opposite, draining more slowly and sinking broadly but shallowly.  Loam soil, the middle type, spreads somewhat and goes down somewhat. 
     Incorporating more organic material in the soil – no matter which type of soil – will help the soil both drain and hold water while providing lots of air spaces for roots to develop.  
 
Which Methods Do I Use?
   Depending on how often you like to wander through your garden, and how much time you’d like to spend communing with each plant – or not – there are several watering methods that may satisfy both your needs and the plants’ needs.  In my garden, I employ all five of these options in different locations and at different times under different conditions.

• Hand-Held Hose – Deal with specific plant needs like needing more water than its neighbors or washing down foliage undersides to get rid of pests.
• Overhead Sprinkler – Wash off dust on foliage for more effective photosynthesis. My father installed an overhead sprinkler for each fruit tree 60 years ago and left the water running overnight for deep watering.  This is impractical now, so I now use it once a month to wash the foliage.
• Mini-Tube Drip Emitter On Timer – Especially good for individual plants spaced far apart so water isn’t “wasted” in between plants. Make sure entire root zone gets moist, not just one limited spot due to the type of emitter.
• Soaker “Leaky” Hose Under Mulch – Made of recycled tires, it drips along the entire length of the hose.  Lay it about 9” apart to achieve moisture going to the entire root zone, especially on fruit trees and intensively-planted raised beds.
• Buried 5-Gallon Nursery Container With Bottom Holes – Fill with water to gradually release into soil 9-11” deep, directly to plant root zones.  Adding a small shovelful of manure or compost into the container will enable each watering to add fertilizer as manure or compost “tea”.  Because water is released so deep into the soil, evaporation is minimal and roots remain consistently moist however hot the summer temperatures are.

 
For more monthly tasks, go to March and April.
 
For major-topic articles by season, go to Homepage.