Show#4
Dr.
Rick discusses container gardening and how to select the
proper
container.
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.
Back to Top
