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Good Growing

Starting a Garden: Irrigation

Sprinkler head

Watering. The inescapable task of any garden. No matter what, at some point, you will need to water your plants. That’s just the fact of the matter here in Illinois. We do get lots of rain, but then there are times we go through some very hot, and dry weather.

Can Watering Wait?

It seems to be commonplace that when I get out to water my garden, it is followed by a day of rain. Even if rain is forecasted in the coming days, don’t wait if your plants are drought-stressed. If you are thirsty now, you get a drink. You don’t wait for one or two days. The same goes for your plants. Yes, it can be quite exasperating to spend the time watering your garden only to have the rain come in a few days later, but if your garden needs a drink, you have to give it water.

How Often?

When and how much we water is highly dependent on several variables, but the main ones are soil type and weather.

Sandy soils are very porous, which means, water can move through them very quickly. On the other hand heavy soils, such as clay, hold on to water and do not drain very quickly. And then you may have constructed soils, such as what you may find in a raised bed. A raised bed soil may resemble your native soil, but more than likely there are significant differences. Usually, a raised bed soil is very well-drained, similar to sandy soil. If your soil is very well-drained, you may need to water two or more times a week during the hot summer days. For more clayey soils, you could get away with irrigating perhaps only once a week.

How Much?

Remember as a child when you wanted to be the weather person on TV? As a gardener, now is your chance. You will be monitoring the weather maps and tracking how much precipitation you get each time it rains. The only equipment you may need to buy for this new job is a rain gauge. Or you can check your local weather station records. Additionally, lots of weather websites offer the service of precipitation records.

You need to know how much rainfall because ideally, a garden will receive one inch of rain per week. If Mother Nature provides it, you’re off the hook. However, if it does rain, but doesn’t get up to a one-inch total, and the soil is dry, you need to make up the difference.

You can determine how much water to applying by knowing the total volume your water system applies (for most of us, that’s a hose). The easiest way is to just use the water meter to see how long it takes to spray out five gallons worth of water. If you can’t use a water meter a five-gallon bucket and a clockwork just as well. Make sure to mark the actual five-gallon volume on the bucket.

Over a 100-square-foot garden one-inch of rain equals about 62 gallons of water. Once you know how long it takes to spray five gallons of water, multiply that time by 12 to know how long it would take to irrigate 100 sq. ft. with your hose and sprayer.

You can also check your overhead sprinklers rate, by turning them on and timing how long it takes them to fill up a rain gauge to 1-inch. A standard tuna fish can also work, as these are 1-inch deep.

Soil type also impacts the rate at which water is absorbed. Heavy clay will take longer for water to penetrate soils and you may get more runoff of water than absorbed into the ground. A good solution for this circumstance is to slow down the rate at which you apply water. Soaker hoses or drip irrigation systems would be an option as a slow delivery method. Set your irrigation to a battery-operated hose timer and sit back and enjoy the garden while your automated system waters the plants.

Too much water can be as much of a problem as too little. Plant roots need to breathe, and a saturated soil does not have much oxygen. Essentially, plants sitting in water for prolonged periods drown. If nature is supplying too much rain, there are few options for a gardener other than watch and wait for the rains to end. Raised beds can be an option for water-logged, or flood-prone soils.

What Options Are There?

There are lots of ways to irrigate a garden. Here are a few things to consider based on the method you choose:

Hose – For most Illinoisans, we need some type of nozzle at the end of the hose to slow the water and make it less of a destructive force, to something gentler so it doesn’t wash away soil and plants. Water wands are useful because they allow gardeners to water near the base of plants without bending over. I prefer to use a shower-type setting on the hose nozzles. Water the roots, not the leaves.

Over-head sprinklers – A lot of gardens are watered using some type of overhead irrigation. It could be a lawn sprinkler or a sprinkler designed for vegetable gardens. These gardens may experience little issues arising from such watering practice. However, there are some things to consider with overhead watering:

  1. Overhead sprinklers use a lot of water. Much of it never makes it into the soil. Instead, a portion evaporates en route to the roots.
  2. Water droplets that land on leaf surfaces and remain wet for prolonged periods are more conducive to disease development.
  3. You can reduce evaporation and disease-favoring environments by watering in the morning. This is during cooler parts of the day and allows the plants to dry in the afternoon.
  4. Not only do you water the rows of vegetables, but also the paths in between, which can be conducive to weeds.

Drip Irrigation – Probably one of my preferred methods for irrigation in the vegetable garden, drip irrigation has become quite popular. In the past, it may have been a foreboding task to tackle, these days garden centers sell kits with everything you need to assemble a drip irrigation system. If you can build Legos, you can put together a drip irrigation system.

  1. Drip irrigation is highly efficient. 90 to 95 percent of the water applied infiltrates into the soil, while the exact opposite is true for overhead watering on a hot and windy day.
  2. Because of their efficiency, drip systems use 30 to 50 percent less water than sprinkler irrigation.
  3. Applying water directly to the soil minimizes leaf wetness and therefore reduces disease occurrence.
  4. Drip irrigation provides moisture directly to desirable plants, while weeds struggle to get the moisture they need.

How Can I Spend Less Time Watering?

Mulch is a fantastic way to reduce the need to be standing out in the garden with a hose in your hand. Preferably use organic-based mulches such as straw, coarse woods chips, or pine straw. These mulches insulate the soil and help conserve water. Avoid using cardboard or newspaper alone, because if they dry, they can begin to repel water and create unfavorable soil conditions. Some commercial growers use plastic mulch or landscape fabric with holes cut or burned in them to allow the garden plants to grow through.


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