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If you do not
have space for a vegetable garden or if your present site is too small,
consider raising fresh, nutritious, homegrown vegetables in containers. A
windowsill, patio, balcony or doorstep can provide sufficient space for a
productive container garden. Problems with soil borne diseases, nematodes or
poor soil can also be overcome by switching to container gardening.
Grow vegetables that take up little space – such as
lettuce – or
crops that bear fruits over a period of time, such as
or miniature varieties often mature and bear fruit early, but most do not
produce as well overall as standard varieties. The amount of sunlight that
your container garden spot receives may determine which crops can be grown.
Generally, root crops and leaf crops can tolerate partial shade. Vegetables
grown for their fruits generally need at least five hours of full, direct
sunlight each day, but perform better with eight to 10 hours. Available
light can be increased somewhat by providing reflective materials around the
plants, such as aluminum foil, white-painted surfaces or marble chips.
Container gardening lends itself to attractive plantscaping. A dull patio
area can be brightened by the addition of baskets of cascading tomatoes or a
colorful herb mix. Planter boxes with trellises can be used to create a cool
shady place on an apartment balcony.
There are many possible containers for gardening. Clay, wood, plastic and
metal are some of the suitable materials. Containers for vegetable plants
must: (1) be big enough to support plants when they are fully grown, (2)
hold soil without spilling, (3) have adequate drainage, and (4) never have
held products that would be toxic to plants or people. Consider using
barrels, flower pots, window boxes, baskets lined with plastic (with
drainage holes punched in it), even pieces of drainage pipe or cinder block.
If you are building a planting box out of wood, you can use rot-resistant
redwood, cedar or cypress.
Some gardeners have built vertical planters out of wood latticework lined
with black plastic and filled with a lightweight medium, or out of welded
wire shaped into cylinders lined with sphagnum moss and filled with soil
mix. Depending on the size of your vertical planter, 2-inch diameter
perforated plastic pipes may be needed inside to aid watering.
Whatever type of container you use, be sure that there are holes in the
bottom for drainage so that plant roots do not stand in water. Most plants
need containers at least 6 to 8 inches deep for adequate rooting.
The imaginative use of discarded items or construction of attractive
patio planters is a very enjoyable aspect of container gardening. For ease
of care, dollies or platforms with wheels or casters can be used to move the
containers from place to place. This is especially useful for apartment or
balcony gardening so that plants can be moved to get maximum use of
available space and sunlight and to avoid destruction from particularly
A fairly lightweight potting mix is needed for container vegetable
gardening. Soil straight from the garden usually cannot be used in a
container because it may be too heavy, unless your garden has sandy loam or
sandy soil. Clay soil consists of extremely small (microscopic) particles.
In a container, the undesirable qualities of clay are worse. It holds too
much moisture when wet, resulting in too little air for the roots, and it
pulls away from the sides of the pot when dry.
Container medium needs to be porous because roots require both air and
water. Packaged potting soil available at local garden centers is relatively
lightweight and may make a good container medium. Soilless mixes such as a
peat-lite mix are generally too light for container vegetable gardening,
since they usually will not support plant roots sufficiently. If the
container is also lightweight, a strong wind can blow plants over, resulting
in major damage. Also, soil less mixes are sterile and contain few nutrients,
so even though major fertilizers are added, no trace elements are available
for good plant growth. Add potting soil if you wish to use a peat-based mix.
For a large container garden the expense of prepackaged or
soil less mixes
may be quite high. Try mixing your own with one part peat moss, one part
potting soil and one part clean coarse builder’s sand or perlite and a
slow-release complete fertilizer. Lime may also be needed to bring the pH to
around 6.5. In any case, a soil test is helpful in determining nutrient and
pH needs, just as in a large garden.
Plant container crops at the same time you would if you were planting a
regular garden. Fill a clean container to within one-half inch of the top
with the slightly damp soil mixture. Peat moss in the mix will absorb water
and mix much more readily if soaked in water before putting the mix in the
container. Sow the seeds or set transplants according to instructions on the
seed package. Put a label with the name, variety and date of planting on or
in each container. After planting, gently soak the soil with water, being
careful not to wash out or displace seeds. Thin seedlings to obtain proper
spacing when the plants have two or three leaves. If cages, stakes, or other
supports are needed, provide them when the plants are very small to avoid
later root damage.
Pay particular attention to watering container plants. Because the volume
of soil is relatively small, containers can dry out very quickly, especially
on a concrete patio in full sun.
Daily or even twice-daily watering may be necessary. Apply water until it
runs out the drainage holes. On an upstairs balcony this may create problems
with the neighbor downstairs, so make provisions for water drainage. Large
trays filled with coarse marble chips work nicely. However, the soil should
never be soggy or have water standing on top of it.
When the weather is cool, container plants may be subject to root rots if
maintained too wet. Clay pots and other porous containers allow additional
evaporation from the sides of the pots and watering must be done more often.
Small pots also tend to dry out more quickly than larger ones. If the soil
appears to be getting excessively dry (plants wilting every day is one
sign), group the containers together so that the foliage creates a canopy to
help shade the soil and keep it cool. On a hot patio, you might consider
putting containers on pallets or other structures that will allow air
movement beneath the pots and prevent direct contact with the cement. Check
containers at least once a day and twice on hot, dry or windy days. Feel the
soil to determine whether or not it is damp. Mulching and windbreaks can
help reduce water requirements for containers. If you are away a lot,
consider an automatic drip emitter irrigation system.
If you use a soil mix with fertilizer added, then your plants will have
enough nutrients for eight to 10 weeks. If plants are grown longer than
this, add a water-soluble fertilizer at the recommended rate. Repeat every
two to three weeks. An occasional dose of fish emulsion or compost will add
trace elements to the soil. Do not add more than the recommended rate of any
fertilizer, since this may cause fertilizer burn and kill the plants.
Container plants do not have the buffer of large volumes of soil and humus
to protect them from over fertilizing or over-liming. Just because a little
is good for the plant does not guarantee that a lot will be better.
The various types of insects and diseases that are common to any
vegetable garden can attack vegetables grown in containers. Plants should be
periodically inspected for the presence of foliage-feeding and fruit-feeding
insects as well as the occurrence of diseases. Protect plants from very high
heat caused by light reflection from pavement. Move them to a cool spot or
shade them during the hottest part of the day. Move plants to a sheltered
location during severe rain, hail or windstorms, and for protection from
Excerpted from the South Carolina Master Gardener Training Manual,