When I first began gardening I was amazed to learn how poorly I watered my vegetables. In fact, I have been astounded to learn how many others were doing the same as me. Hopefully in this post I can help explain how often, how much and why overwatering will yield poor results.

First, the frequency. All of my vegetables are on one of three different watering schedules.

• Twice a week schedule for water loving plants like strawberries, lettuce, onions, brocolli, cauliflower, carrots, peas etc.
• Once a week for summer crops like peppers, beans, corn, squash, cucumbers and eggplant.
• Once every two weeks for hot crops like tomatoes, and melons.

I will water a little more frequently when temperatures are pushing 100 degrees, but generally that is the schedule. The trick is to water deeply, but infrequently.

That leads to the question of how much. Of course this will depend on your drainage, evaporation and many other factors, but a basic rule of thumb is 1 inch of water will soak down 1 foot, 2 inches of water will soak down 3 feet and 3 inches will soak down really far. Therefore, I try and water 1-2 inches at each watering for water loving plants and 2-3 inches for once a week plants and 3-4 inches for hot crops. This means that I will leave my drip irrigation hose, which emits 2 gallons per hour, per emitter, with emitters 1 foot apart, on for about 1-1 and 1/2 hours for water loving, 2 hours for once a week plants and 3 hours for hot crops.

So what is the big deal you may ask? Watering schedules are important for plants because the same reason that plants need water to grow they also need oxygen. Overwatering will prevent your plant from getting the oxygen it needs. It will also prevent it from getting important nutrients into the roots like iron. Most importantly there is a phenomenon in plants called the source-sink relationship. This is a bit hard to explain without a white board, but lets see if I can make it simple.

Plants make all of the fruit sugars, proteins etc in the leaves. So in order to make fruit a plant must first make leaves. This is called the vegetative stage. Plants need water, nutrients etc. and the plant knows to send its energy into this process. Somewhere along the way the plant goes into a fruiting stage. It stops putting energy into creating leaves and begins to put it into the fruit. All of the fruit is being made in the leaves (the source) and then it must transfer this food into the “sink” or the fruit.

So what does all of this have to do with watering schedules? Well, when you overwater the plant it will not naturally go into its fruiting stage. It will stay in its vegetative stage and keep producing leaves and new growth. Basically, it still thinks it Spring because it keeps “raining”. For the same reason, you will want to stop side-dressings of fertilizers/nitrogen after a while so that the plant will not stay in the vegetative stage.

So for those of you who grow beautiful tomato plants with hardly any tomatoes, it is because you are watering too often. Trust me on this and if you don’t then ask the experts. This is especially important for tomatoes since over/under watering will cause blossom end rot. Don’t be worried if you see blossom end rot of the first few ripe tomatoes, this happens all of the time, however, it should only be on the first few and not the rest.

We do have a problem in Utah with tomatoes cracking. Therefore, after the plant has successfully gone into the fruiting stage, (it is making lots of tomatoes) then I begin to water once a week to help prevent cracking.

I use these practices in my own garden and get great results. I have yet to have a plant die due to lack of water, however, I have had many problems in the past due to overwatering. For more important information on irrigation practices please see another post on the subject.

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