May
07
2014

Effects of Water Quality on Plants

It would be very sad if one day you turned on your hose, watered your plants and they died. It’s not science fiction. While that does not happen to most people in America, it does happen to some whose water supplies have been compromised. Livestock waste, heavy metals, fracking and industrial waste are just a few of the participants in contaminating our water supplies. Sadly it will only get worse. Water is one of the most precious commodities on earth. As population and industry grows we will further affect this lifeline of all living things. Even if your garden does not curl up and die when you simply water it there is a good chance your plants are not as happy with their water as you think. Chloramines and excess salts (hardness) are a toxic meal for plants and a constant in most municipal water supplies. When found in heavy amounts they can have a big effect on what you grow and how plants mature and ultimately produce. While it’s not crucial that you treat your tap water for plant growth, it’s something to be aware of since most gardeners never think about it. If you have any concerns that your tap water may be harming your garden, read on and re-examine your gardens water supply.

Who likes to organic garden? I do! Nowadays, going organic is not just reserved to new age moms from San Francisco. Many people are making the change. Organic foods often taste better and with all the chemicals being used around us on a daily basis it’s nice to know what we are putting in our bodies. But if you have organic soil and use organic nutrients and pour water with chlorine and chloramines all over them, you are killing all the living microbial activity that makes organic gardening, well, organic gardening. When someone says “I have great soil”, what they’re really saying is my soil is alive. The organic process in your garden requires living microbial bacteria to break down plant food in the soil that is not readily available to the roots. Chloramines are the necessary evil we live with on a daily basis which mankind uses to kill bad bacteria. But unfortunately it also kills this good bacteria that are used by all plants. What you should know is how easy it is to attach a dechlorinator before any drip system.  A dechlorinator is exactly as it sounds, it takes nearly all of the chlorine and chloramines out of your water. Dechlorinators are inexpensive and very easy to set up and they make different sizes for different applications. Small dechlorinators work great for hand watering and general use. Larger dechlorinators can be purchased for use in a drip system or inline with your home’s water main. A cheaper solution is to fill up an uncovered barrel or holding tank and allow the chlorine to slowly dissipate naturally over a 24-48 hour period. Using an air pump or water pump in the barrel or holding tank will help speed up the process. Even though a lot of the chloramines will still be in the water, the idea is that any reduction in chlorine levels are better for the plant.

Water hardness is another major problem in most city water and wells. Hard water is caused by an excess amount of minerals in your water. Ironically, these excess minerals are the same minerals found in most complete plant nutrients. The problem is the heavy concentrations cause massive salt build-up on the roots and in the media which can cause nutrient lockout of varying degrees. At the very least your plants won’t uptake a proper balance of all the nutrients they require. At worst the plant can stop getting major nutrients required for normal growth which will eventually cause the plant to die. The most common cause of hard water is excess calcium, magnesium, iron and sulfur. All these minerals will collect on the roots much like they do on faucets and appliances in your home. Get a water sample from your water district or take in a sample of your well water to find out if you have hard water. You can also take a general ppm reading with a digital TDS meter. If your water is over 250 parts per million you should consider treating your water. if your water over 400 ppm you should definitely treat your water. Unfortunately, the only way to treat hard water is with a water filtration or reverse osmosis system or a water softener.

PH is also a very important factor in water quality and plant need and requirements. The reason is actually very simple but few people know why. PH of your water, after nutrients and anything else has been added, should fall between 5.8 and 6.8. When pH is too high or too low nutrients in the water become unavailable to the plant as seen in the chart below:

So as you can see, when pH is too high, micronutrients become less available. When pH is too low the macro and secondary nutrients are most affected. Additionally, if you constantly use water with a pH that is too high or low the soil slowly drifts towards towards that unsatisfactory pH level eventually causing a complete shutdown of the plants ability to use and store the proper levels of critical nutrients. PH test strips or drops or a pH meter are great ways to test and monitor the pH in your water. Once identified you can use a pH solution to adjust the pH level. If you are using tap water and you identify high or low pH levels you can use amendments in your soil before planting or spread around the base of your plant to help correct the problem. To raise pH most people use dolomite lime. Dolomite lime contains magnesium so if your water already contains a lot of magnesium try calcitic limestone. Wood ash and oyster shell are 2 other natural amendments that will help correct high pH in the soil. Lowering pH is more difficult. Elemental sulfur is popular but must be used cautiously as it’s easy to apply too much. Peat moss is very acidic and can be mixed into the top 8-10” of soil. Home remedies include coffee grinds, ground up pine needles or home-composted leaf and vegetable refuse. When acidifying your soil with these home based options, monitor the progress of your plants for a month or two as results can vary widely.

I’d like to end this article on a good note and that is, most home water is going to be just fine for your yummy yams and beautiful begonias. More advanced summer crops often require more nutrients and care than more forgiving crops like flowers and herbs so it’s never a bad idea to investigate your water and do a couple checks. As we said earlier, we recommend 1) checking your water’s pH and 2) checking the total parts per million (ppm) or get a water analysis from your water district. Water is just one of those things that many gardeners overlook and take for granted. Commercial growers take extreme steps to make sure their water is always tip top since poor water quality can lead to complete failure and even bankruptcy. Water is the key to life for all living things. Thinking and acting proactively to your garden’s water needs is one of the steps you need to take to insure a healthy happy garden.

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