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Watering   Houseplants

Over watering is one of the greatest killers of house plants. The most common questions home gardeners ask is, "How often should I water my houseplants?" There is no absolute answer to this question. It is impossible to set a time schedule for watering plants. The frequency of watering depends on many factors such as type and size of plant, temperature and humidity within the home, weather conditions and season of the year.

In general, it is a sound practice for most house plants to let the soil dry out somewhat between watering. To determine if a plant needs water, test the soil by poking your finger about half an inch down into it; you will be able to feel how wet or dry it is. Also look at the soil; it normally will be lighter in color when dry. If you have real difficulty in determining if your plants are too wet or too dry, soil moisture indicators can be purchased. These are very useful in getting to know the water needs of your plants. Of course, there are exceptions to the above general rule. Plants such as the Boston Fern, Caladium and Zebra plant won't tolerate dry soil. They should be watered often enough to keep the soil surface from becoming dry. Dieffenbachia and Schefflera plants need less water than the normal plant. They should be watered until the soil has been dry to the touch for one or two days. Cactus and Succulents prefer a dry environment and thus the soil should be allowed to dry out well between watering.

The next question to answer is: "How much water should be applied?" The general rule is to add enough water so that a small amount runs out of the drain hole in the bottom of the pot. This guarantees that all the roots get properly watered. It also washes some of the excess salts (fertilizer residues) out of the pot.

Sub-irrigation (watering from the bottom) is a very popular and acceptable watering method, especially for African Violets. Do not allow the pot to stand in water once the soil surface is wet. To prevent excessive accumulation of fertilizer salts flush the soil from above several times a year.

Pots without holes need a longer period between watering since there is no outlet for excess water to drain through. When you water apply just enough to wet the soil to the bottom of the container. Be careful not to over water. Remember there is no place for the extra water to go. Since it is so difficult to grow plants in pots without drainage holes I would like to discourage using this type of pot.

When watering your plants, the water temperature is particularly significant. Don't use ice cold water, especially on tropical plants. The water should be at room temperature and applied in the morning whenever possible. Allowing tap water to warm up to room temperature also allows water additives to evaporate or settle out in the water. These additives can cause the browning of plant leaf tips. The prolonged use of water from a softener usually results in poor plant growth

Todd Weinmann, Extension Horticulturist & Master Gardener Coordinator
Phone: (701) 241-5707

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