Keeping Containers Happy and Healthy

Barb Mrgich
Adams County Master Gardener

This is the time of summer when containers should be really filling in and getting nice. Individual or grouped containers can make excellent accents for outdoor décor, but always remember anything stuck in a pot depends on you for nutrition and water.

A plant in the ground has the advantage of nourishment and water from a wide source. A container plant has only what is contained in that pot and is solely dependent on you to supply for its needs. A plant in the garden may or may not need fertilizer during the growing season. The plant in the pot needs to be fed regularly.

As an organic gardener, I do not buy chemical fertilizer for my in-the-ground garden plants. It does not build the soil. However, chemical fertilizer will feed plants just fine, so I use it in containers. Each time a container plant is watered, nutrients are washed out the drainage hole of the pot. They need to be replaced regularly using just a small amount of fertilizer at a time if plants are to remain healthy.

When summers are especially hot and dry, we are asked to conserve water. However, watering containers is usually permissible. Fortunately, there are other ways to get water to plants without relying on the hose. I get about a gallon of water a day just from the overflow pipe of my central air conditioner. Too, how long does the water run waiting to get hot when the tap or shower is turned on? That is a lot of water down the drain that could be used for plant watering.

Consider installing a rain barrel or two. Water collected in a rain barrel is the absolute best water to use because it is untreated. Even more important, using rain barrels to collect rainwater is a recommended way to help eliminate stormwater run-off from leaving private property.

Obviously, with 90+ degree sunny days, containers will dry out quickly. When I plant mine, I use a good bit of compost which is known to help soil hold onto water longer. I use fairly large containers, and because of the compost I only need to water them every other day.

Pay close attention to the tag when buying a plant. Some will say to let the soil dry out between waterings, and some will say to keep the soil constantly moist. There is a big difference. Do not put both plants together in the same pot.

The type of container you use also helps determine how often there is a need to water. Terra cotta pots will dry out the fastest, and those thin plastic hanging pots from the nursery filled with only potting soil are useless on very hot days. No wonder plant tags tell you to water them two or three times a day. I like the thick glazed pottery containers. They are heavy to move and expensive, but they hold onto water and I really like the way they look. If pots seem to be drying out too quickly on hot days even though they are full sun plants, it may be smart to temporarily move them to where they will get a little light afternoon shade.

Do noy be fooled by short rains. Waking in the morning after an overnight rain and seeing puddles on driveways, roads and other hard surfaces does not always mean pots do not need to be watered. Sources sometimes advise to stick a finger into the soil to see how far down it is damp. Good advice, but I do not like dirt under my fingernails, so I use a handy dandy little water meter. Sticking its prongs down into the soil indicates the amount of moisture in the soil. After a brief rain, the soil in some pots will be wet on the surface, but if the prongs of the water meter indicate the soil is dry, believe that the soil is dry. If there are doubts, dig down a little into the soil to check it. It will be dry.

When watering, be sure the water is running out the drainage holes in the bottom of the pot. Never put a plant in a pot that does not have drainage holes. The plant will drown. Try to put water directly onto the soil, not on the plant foliage. Always remember, wet foliage encourages disease. Mulch can be useful to help keep the moisture a little longer in the container just like it does in the garden. But mulch is also a great deceiver. After a short rain, the soil beneath the mulch might not even be wet.

When it comes to selecting watering equipment, a drip hose or some type of drip irrigation system cannot be beat for making the most efficient use of water. If containers are arranged on a timed drip irrigation system, they may never have to be watered by a hand-held hose ever again!

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