Good drainage crucial to any potted plant

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Last Updated: 
October 4, 2004

CORVALLIS - Both indoor and outdoor plants require good drainage for a healthy root system. If you have either indoor or outdoor container plants, be on the lookout for salt buildup on the soil surface or pot, according to Ross Penhallegon, horticulturist with the Oregon State University Extension Service.

Whitish-colored deposits, composed of salts built up from hard water and fertilizer, usually indicate insufficient drainage or not enough flow-through of water. To avoid salt build up, water your plants each time until liquid runs out of the bottom of the pot, recommended Penhallegon.

To keep soil from washing out of the hole at the bottom of the pot, place gravel or broken piece of pottery over the hole.

Unfortunately, some plant containers such as terrariums, plastic pots provided with bulb forcing kits or decorative gift plant containers do not have drainage holes. If you own such a pot and want to use it to grow plants, transplant your plant into a pot with a drainage hole. Then place the planted pot with drainage into your pot without a drainage hole.

Check the level of the water in the bottom of the larger container regularly. Any excess water applied to the smaller pot will accumulate in this area.

Penhallegon recommends removing salts and hard water deposits out of potted soil once per month, by flushing a potted plant with lots of water. For example, each month, you would flush a one-quart potted plant with about a gallon of water.

Keep the water in the bottom of pots or terrariums to a minimum. Root injury will occur if a plant's root system is submerged in water for very long. Any excess water should be poured out of the larger container periodically.

Another way to make sure closed-bottomed potted plants get adequate drainage is to line the bottom of the pot with charcoal. Then cover it with a layer of coarse gravel. Next, add potting soil and place the plant. The water will drain through the soil to the gravel and the charcoal layers. Be sure to apply just enough water so that the water level in the gravel layer is not touching the soil. The charcoal will assist in removing some noxious gases and other materials from the water.<?P>

Author: Carol Savonen
Source: Ross Penhallegon