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Dr. Rick discusses container gardening and how to select the proper

As temperatures warm up and we start thinking about container gardening, one frustration always causes Southerners concern. Containers are difficult to water and care for when temperatures begin to soar. It is not unusual to have to water them every day. Let me share some advice with you on how to select and prepare your containers to be able to deal with the intense temperatures of June, July, and August.

First, consider containers made of plastic or something other than clay. Clay pots breathe and this is great if our plants lack air but not so good if you're trying to keep your plants from drying out. If you do choose clay try lining the inside sides of the container with plastic. Make sure water can drain out the bottom if necessary. We don't want to create a swamp in the bottom of the container. Rocks or clay potshards are not necessarily a good idea in the bottom. But it isn't a bad idea to put a layer of landscape fabric across the bottom, if the soil you choose tends to drain out the hole in the bottom.

Soil selection is a critical ingredient to success with containers. A good rule to follow is put your money where your dirt is. Do not go with the cheap soil, as it will haunt you all summer long. The first criterion for good container soil is it must be soil-free. In other words, you don't want any mineral matter in the soil at all. No sand, gravel or anything you've dug up out of the ground. You may save a little bit with a cheap mix but it is often filled with weed seeds and does not encourage the correct ratio of air and water. A premium soil mix will create an environment that holds 25% water by volume, 25% air by volume and 50 % potting mix. In general, purchase the lightest mix you can find. A combination of peat, perlite and vermiculite is your best bet.

Let's take a quick look at each of those. Peat comes from bogs where it has been submerged underwater for many years and years. Peat comes in various stages of decomposition and is particularly acidic. It does an excellent job holding water in the soil mix. Perlite is a volcanic rock material that has been heated up to 1800 degrees. It extremely light and does an excellent job of providing air in the soil. We want a little of this in our mix but not too much as our soils will dry out too fast. Vermiculite is mica like material that has been heated to very high temperature and expanded just like popcorn. Vermiculite is an excellent water holding component, so we want a pretty high level of this in our containers. There are numerous other ingredients you look for. Bark is often part of the mix as a substitute for peat. Try to avoid too much bark unless the particles are very small and you are sure that it is totally composted.

The size and shape of our container also affects how much moisture it will hold. Believe it or not containers that are tall and narrow tend to drain faster than wide, squatty ones. Here's why. Pretend this sponge is the soil in your container. If I completely saturate this sponge with water it doesn't drip when it is held horizontally. But take the same sponge and turn it more vertically much of the water drains out. It is because the water column is longer and the water pressure is greater from above. Select containers that are wider than they are tall if you want them to drain slower and therefore hold water longer.

Coring a container involves placing a core of dense, water-holding material at the bottom of the container. One of my favorites is pure clay soil mixed with a little water absorbing gel. This is some interesting stuff that really holds moisture. Once it touches water it absorbs many times it weight and swells up. As the soil begins to dry out the water absorbing gel begins to dry out and releases water into the surrounding soil. Fill up a small pot with clay and water absorbing gel and turn it over into the bottom of the container and remove the pot. Here is your core of water holding material. Fill around the core with good potting mix up the rim. When the soil is moistened it should compact a bit and allow for a lip to form so water will not run off from the soil as you water.

As you plant, try to place your plants at a 45-degree angle around the edge. As they fill in, they will fill up the middle and cascade over the edge as well. Something taller in the middle such as this ornamental grass should be approximately 1 ½ to 2 times the height of the container to make it feel proportional. Use a slow release fertilizer and you can even supplement it with a little with a high middle number. That's phosphorus and it is responsible for lots of flower and root growth. You may want to add a little mulch on top to insulate the soil and keep it from drying out so fast. Otherwise, your container plants should thrive in this type of environment all the way to frost next fall.

Different types of mulch.

Pruning Forsythia and Holly

Erin visits Turnipseed Nursery

Turnipseed is located in Fayetville, Georgia.
Its phone number is 770-460-8534.

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