How to Irrigate a Garden

Overhead sprinkler in my garden

Water is one of the limiting factors for growth in gardening in the dry summers of the Pacific Northwest. Though it is possible to dry farm (grow with little to no irrigation), if you have limited space, irrigation is necessary.

Drip irrigation is the most efficient and works great if you plant in rows and do not need to disturb the tubing/emitters. If you have a low producing well or live in a drought, this is a great option. I use this for my food forest. Fertigation is another option (spraying the plants with compost tea or a fertilizer water mix).

The traditional method is overhead sprinklers. These ideally have overlap to avoid blind spots. I currently use 4 of these — one in each corner of my garden. Each has a good deal of overlap. Since my irrigation well is low production, I purchased a triple timer and a single one and time them to wait an hour between watering again for the well to fill again. It has not dried up yet, so I recommend this method for low production wells. I have a 1hp pump with built in pressure tank that I purchased for around $120 and I dug a 1” line about 250’ from the well to my garden. This has worked great so far. Overhead irrigation is less efficient and wastes more water than other methods. So if water is expensive or limited, this is not ideal.

I also have a raised bed with small sprinklers along one edge. This works well also.

Using automatic timers is a great way to save the hassle of having to remember to turn on sprinklers manually and can keep your garden alive when you are on vacation. Keep an eye on your irrigation though as I have had a couple instances where my timer was not setup or working properly putting my plants back quite a bit.

1-2” of water a week is the rule of thumb. Place a small bucket if you use overhead sprinklers to see how long you need to irrigate. With drip irrigation, read what your emitters advertise in gallon output and research what your plants require.

If you live somewhere with dry summers, one of these irrigation methods is a must. If you live somewhere summers are wet like the East coast, irrigation can still be important but no where near as essential. Keep an eye on your plants for wilting and occasionally feel the soil. Mulch can make your watering go further.