vegetables is great fun, good exercise and a sure way to more nutritious
eating. But for many of us, simply wanting to plant a garden may not be
enough. We may lack a good site, or be too busy with other things. Container
gardening is a simple and fun way to grow edible crops in just about any
situation. It’s growing in popularity because it’s easy to get started and
enables anyone to be successful— including those who think they have a “brown
thumb”. Even if you have an in-ground vegetable garden you may find it
desirable to have edible containers of herbs and salad greens near the kitchen
door. This fact sheet has the basic information you’ll need to grow some of
your own organic produce spring, summer, and fall!
The Growing Advantages
perfect for all kinds of people— kids, people with physical limitations,
college students, renters, novice gardeners, and any gardener wanting to cut
back, downsize, and save time. (You can water and harvest 10 containers in 10
There is no digging or tilling. You can garden in he rain
without getting your shoes muddy!
Container gardening is virtually weed-free.
It’s inexpensive to get started. Few tools are needed.
Helps to overcome some common gardener complaints:
backyards that are too shady for tomatoes compacted, poor
quality soils and soil contaminated with lead persistent soil-borne disease
tomato. Temporary or permanent containers (including window boxes) can be
fitted to any location.
balcony, deck, stoop, concrete pad, or any part of your
yard. You can locate containers where they are most convenient for you and
where they will grow best (place the tomatoes in full sun and the lettuce in
partial shade.) Better
control over growing conditions (water, sunlight, nutrients) can lead to
higher yields with less work than a conventional garden (10 sq. ft. can
produce 50 lbs. of fresh organic produce).
are easier to protect plants from weather extremes, insect pests and bigger
Get a quicker
start in the spring and grow further into the fall.•
Vertical growth saves space and allows use of exterior walls.
Organic gardening emphasizes soil improvement through the
regular addition of organic matter, and biological and genetic diversity to
manage insect and disease problems. A growing number of Marylanders are
interested in buying and growing organic produce to reduce exposure to
chemical pesticides. For most gardeners, “organic” means no chemical
fertilizers or pesticides. Luckily, it’s pretty easy to grow container
vegetables organically. There are many types of organic fertilizers. And
spraying, even with an organic pesticide, should rarely be necessary. This
fact sheet emphasizes organic and sustainable growing practices that will
save you money and put nutritious food on the table. For example, using
recycled materials for containers, filling those containers with backyard or
locally produced compost, and planting flowers to attract beneficial insects
are all ways to create a low-cost, ecological garden
There are a few simple ingredients for success— a little bit
of room, sunlight, containers, growing media (a.k.a.“ potting soil”), water,
and nutrients (fertilizer). The single most important ingredient for success
Care because your
container plants have to depend entirely on YOU for all of their needs. It’s
always best to start small the first year. Share ideas and create a plan
with the other people in your household. Plant crops that you and your
family like to eat, and keep your containers filled with edible plants
through the entire growing season.
Incorporating containers into outdoor living space requires
some basic knowledge about the needs of the plants you want to grow. An eye
for design will produce more pleasing, aesthetic results.•
Containers can be
placed on any level surface—decks, balconies, and along driveways and
sidewalks. You can also set them on bare ground and allow the plant roots to
grow down into the soil or place them on top of a mulched area. Edibles can
also be grown in hanging baskets and window boxes.
Southern and western
exposures will be the sunniest and warmest, while northern and eastern
exposures will be shadier and cooler.
You’ll need 6-8 hours
of direct sun for warm season crops (tomato, pepper, eggplant, squash) and
3-5 hours of direct sun for cool-season crops (lettuce, spinach, Asian
Easy access to water is
crucial. Some containers will need watering every day when the weather is
hot and dry. Consider the microclimate in the container garden area. Watch
out for heat sinks created by brick, concrete, and reflective surfaces.
Containers and the water
that drains from them can ark and stain concrete and wood decking. Using
self-watering containers or plastic saucers to catch water will prevent this
problem (and is very helpful if you are gardening “above” your neighbour’s
The light weight of large
plastic containers leads gardeners to believe they can be easily moved. Buta
20-inch diameter container filled with moist growing medium and plants can
weigh 100 lbs! You can buy or make plant caddies to make heavy containers
Containers can be temporary or permanent, practical or
whimsical, artistic or utilitarian, expensive or free. When selecting
containers, use your imagination and creativity, and know how much room your
crops will need to grow to their full potential. And you’ll need to decide
where and how to store the containers that are portable and used only during
the growing season.
Dozens of commercially produced containers can be purchased at garden
centers and through mail order catalogs (see “Resources” on page 8).Dozens
more everyday objects can be recycled or transformed into suitable
containers- 5 gallon plastic buckets, truck tires, hypertufa troughs, wooden
crates, ½ whiskey barrels, nursery pots, kids’ wading pools, plastic trash
bags, and plastic storage containers.
Avoid treated lumber products and be aware that plastics not made for
outdoors use can become brittle from exposure to the elements.
Except for the self-watering types described on page 5, all containers
should have holes or slats in the bottom to allow water to drain out.
Dark colors will create higher temperatures that could injure young tender
roots and prevent the full development of a plant’s root system.
Containers made from porous materials (clay, ceramic, concrete, and wood)
will dry out more quickly than containers made from plastic, or metal.
the “Dirt” on Growing Media?
The material that your plants grow in is called the “growing
medium”. Dozens of different ingredients are used in varying combinations to
create homemade or commercial growing media. By understanding the functions
of growing media, you can evaluate the qualities of individual types and
select which ones might work best for your container vegetable garden. The
choice is very important because your plants are dependent on a relatively
small volume of growing medium. Unlike their cousins growing in garden soil,
containerized plant roots cannot grow around obstacles or mine the soil far
and wide for nutrients and water.
• Growing medium
has three main functions- 1) supply roots with nutrients, air, and water, 2)
allow for maximum root growth, and 3) physically support the plant.
Roots grow in the spaces between individual particles of soil. Air and water
also travel through these pore spaces. Water is the medium that carries
nutrients that plants need to fuel their growth, and air is needed for root
growth and the health of soil microorganisms that help supply plants with
• Irrigation water
moves through the pore spaces, pushing out the air. If excess water cannot
drain away, fresh air cannot enter and roots will suffocate.
• Select light and
fluffy growing media for good aeration and root growth.
Qualities of Different Types of Growing Media
Garden Soil— never use this by itself for container gardens. Soils hold
water and nutrients very well and can drown roots growing in a container.
Diseases and weed seeds can also be a problem. And soil is heavy which is an
advantage if you are trying to anchor top-heavy plants and pots, but a
disadvantage if you want to move pots.
Commercial Soil-Less Mixes— these are an excellent choice for containers.
They are light weight, drain well, hold water and nutrients, and are
generally free of weeds, insects, and diseases. They have a pH of about 6.2
and are typically comprised of sphagnum peat moss, perlite, vermiculite and
small amounts of lime and fertilizer. Examples of soil-less mixes are Pro
Mix™, Reddi Earth™, Jiffy Mix™, and Sunshine Mix™. (To produce “organic”
soil-less mixes, suppliers omit chemical wetting agents and substitute
organic for chemical fertilizers.)
Other Types of Commercial Mixes— are advertised as “top soil”, “planting
soil”, “planting mix”, or “potting soil”. They vary a great deal in
composition and quality. Avoid mixes that contain edge peat, feel
heavy or gritty, have very fine particles, or appear clumped.
Sharp Sand— use only coarse builder sand, not play sand. Sand increases
porosity because of the large particles. It is relatively inexpensive and
Bark Fines and Wood Mulch— these are high in carbon and low in nutrients and
not recommended for container vegetables.
Compost: In a Class By Itself
Compost is the dark, crumbly, earthy-smelling product of
organic matter decomposition. Leaves, grass clippings, wood waste, and farm
animal manures are some of the common ingredients that are combined with
water in piles or windrows and digested by huge populations of oxygen loving
microorganisms. Leaf Gro™ is a well-known commercially available yard waste
compost in Central Maryland. It’s highly recommended to include some compost
in the growing media for your containers.
Compost contains all the major and minor nutrients that plants need for good
growth. This makes it an excellent substitute for sphagnum peat moss, which
has very few nutrients (although it does hold water better than compost).
Composting effectively recycles the nutrients from gardens, landscapes, and
farms thereby reducing nutrient pollution of waterways. However, fertilizing
is still necessary because the nutrients in compost are released slowly and
are usually not sufficient for an entire season.
Vegetables, herbs and flower plants can be successfully grown in 100%
compost or leaf mould. Baltimore City community gardeners have been doing
this for decades!
Vegetable plants generally grow best when soil pH is in the 5.5-7.0 range.
Many composts have a pH over 7.0 but research has shown that there is no
benefit in reducing the pH to a more desirable level, because nutrients in
compost are available over a wide range of pH values.
Properly made compost is turned multiple times and reaches temperatures that
kill weed seeds and plant and human pathogens.
The limited volume of
growing medium available to container vegetable plants makes it critical to
keep the root
system moist at all times.
Watering needs will vary
depending on container size, ambient temperature, wind, sunlight, and
humidity. You can count on watering most container vegetable plants daily
during the summer months. The growing media should always be moist, but not
soggy. Add water slowly until you see it drain out the bottom (except for “selfwatering”
a watering can or nozzle on the end of a hose that produces a soft stream of
water. Be careful not to use hot water! It can burn leaves and young roots.
Eating quality and yield will be greatly reduced if plants are allowed to
wilt due to a lack of water. Drought stress will kill feeder roots and slow
Water-holding polymers can be purchased and mixed with growing media to help
containers retain moisture. Although effective, these products are not
necessary for success.
Small containers dry out more quickly than large containers. Use a saucer to
catch excess water.
Large, mature plants need more water than seedlings and young plants.
Micro-irrigation with soaker hoses and drip emitters is efficient,
convenient, and relatively inexpensive. You can water all of your containers
automatically using a series of drip emitters on a timer.
Regardless of the growing media used you will need to
fertilize plants regularly. University of Maryland researchers were able to
double pepper production when 5-gallon buckets containing 100% compost were
fertilized, at planting, with a slow-release fertilizer. This occurred
because nitrogen is
usually the limiting nutrient.
This highly soluble nutrient is required in large quantities by vegetable
crops and is easily lost in the water that drains from the bottom of your
The questions “how much” and “how often” to fertilize will
depend on many factors— type of fertilizer, plant needs, type of container,
Even “quick” crops like leaf lettuce or broccoli raab that mature in 35-45
days may need to be several times.
Long-season crops like tomato, cucumber, eggplant, and pepper may need to be
lightly fertilized every 2 weeks or so, to produce acontinuous harvest.
Soluble fertilizers in liquid or powder form are very convenient to use and
effective because the nutrients are immediately available. They are mixed
with water and poured around plants according to label directions.
Liquid sea kelp and fish fertilizer, and compost tea are excellent organic
fertilizers that you mix with water and apply around plants.
Blood meal, composted chicken manure, nitrate of soda, cottonseed meal and
alfalfa meal, and worm castings are all dry organic fertilizers that you can
mix into growing media at planting and re-apply as needed.
Many non-organic fertilizers are available for container gardening. They are
usually either fast acting soluble “plant foods” that are mixed with water,
or pelletized slow-release fertilizers that are relatively expensive but can
provide nutrients for 2-4 months.
NOTE: never add lime, wood ashes, or gypsum to any commercial growing media
or compost. Limeis already added to commercial soil-less mixes.
Compost, either commercial or backyard, has a pH of 6.8-7.5
(a soil pH of 6.2-7.2 is a good range for most vegetable plants.) And always
follow fertilizer label directions.
How to plant and care for your container garden
What can I grow?
Just about any vegetable or herb! Some of the more popular container crops
are salad greens, peppers, eggplant, tomatoes, beans, chard, beets, radish,
squash and cucumbers.
More challenging crops include melons, corn, potatoes, and sweet potatoes.
The key is to experiment.
Look for “bush” or “dwarf” varieties of the crops you want to grow. There
are quite a few tomato and cucumber varieties bred for small-space
How big a pot do I need?
Match container size to plant size, both the top growth and root system.
Don’t squeeze large plants into small containers. Restrict root growth too
much, and plants don’t grow well. It’s useful to consider both the depth and
total volume of your container
Recommended media depth:
4-6 inches: salad greens,
Asian greens, mustards, garlic, radish, basil, cilantro, thyme, mint, and
marjoram. (Salad greens and some herbs have shallow, fibrous root systems
and are well suited to shallow containers with a large surface area).
8-12 inches: beans, beets, chard, carrots, chard, cabbage, pepper, eggplant,
tomato, squash, rosemary, parsley, lavender, and fennel.
Required pot volume:
gallons: herbs, green onions, radishes, onion, chard, pepper, dwarf tomato
or cucumber, basil.
gallons: full-size tomato, cucumber, eggplant, beans, peas, cabbage, and
• Don’t fill
the bottom of the container with pebbles, gravel, or rocks unless you need
the added weight to prevent tipping. Cover drainage holes with mesh, gravel,
paper towel, or a coffee filter, to prevent soil from washing away.
Prior to planting, use a trowel or your hands to thoroughly work water into
the growing medium. This is especially important for soil-less mixes
containing peat moss.
Don’t cram media into container. Fill to within an inch or so of top of
container. Follow seed packet directions for planting, spacing, and care.
attractive and versatile containers, mix herbs and annual flowers in with
the vegetable plants.
Herbs such as lavender, thyme, oregano, marjoram, and chives require a loose
growing medium, and dry conditions. Plant them together in porous clay pots
and add some sand to the mix.
Keep containers together to increase humidity and water retention
Keep those plants growing!
Three-season planting (a.k.a. “successionplanting”): When spring lettuce or
radish is spent, pull up and compost the plants. Then re-plant the container
in late May with pepper plants, beans or cucumber seed. In early fall you
can plant kale, lettuce or broccoli raab to finish out the season. Don’t
forget to fertilize after each crop!
Give them support. Cucumbers, pole beans, peppers, tomatoes, and eggplant
will all benefit from some type of vertical support.
Move plants around if containers are portable to maximize sunlight (for
heat-loving crops) and shade (for summer-grown salad greens).
Trouble in Paradise: Diagnosing Plant Problems
Container-grown plants are subject to the same insect and
disease problems as garden- grown plants, but container gardeners tend to
have fewer problems. The biggest causes of plant problems are lack of water
and nutrients, and overcrowding. Plants can also suffer root rot from too
much water, especially if the growing mix does not drain well. Go to
plant diagnostics. umd.edu
for additional help in
diagnosing vegetable problems.
“Self-Watering”Containers: The New Wave
“Self-watering” containers represent a relatively new
gardening concept. Instead of drainage holes in the bottom, these containers
have an overflow hole on one side. The growing medium sits on a perforated
platform directly above a water reservoir. Plant roots grow through the
medium and into the water. In most cases, water is wicked up from the
reservoir into the medium. These containers can be seen as a hybrid between
(plant roots growing in nutrient-enriched water) and
conventional container gardening. Self-watering container
help conserve water and nutrients and make it possible to ignore your
containers for a few days. The simplest application is to place a saucer
under a pot. The excess water is wicked up into the media or pulled up by
roots that reach the saucer. A number of commercial models are available
(see “Container Gardening Resources”on page 8) or you can make your own.
Convert a 5-Gallon Bucket into a Mini-Garden
The ubiquitous five-gallon plastic bucket is considered by
some to be the most useful tool on earth, particularly in poor countries.
Thousands are buried in landfills or burned each day in the U.S. Thrifty
gardeners rescue them from local businesses and use them to harvest, store,
and protect crops, carry water and tools, spread compost, and make compost
tea. University of Maryland researchers have designed a new use: a
mini-garden for vegetables and herbs that recycles water and nutrients and
uses only compost as
the growing medium.
5- gallon plastic bucket and lid (food grade). Bakeries,
delis, and restaurants will often give them away.7.5-inch section of 4-inch
diameter perforated drain tile6-inch section of ½ inch (inside diameter)
plastic tubing1 ½ inch wood or decking screw electrical tape empty 1-gallon
Saber saw, drill, 5/16 inch and 3/4 inch drill bits, utility
(see illustration below):
1) Using a saber saw or band saw cut the lid so that it fits
inside the bucket. (The lid will separate the medium from the water
2) Drill 15 holes, 5/16" in diameter, in lid. (Plant roots
will grow through the medium and pass through these holes into the
3) With a hacksaw, cut 3 pieces of 4-inch diameter black
perforated drain tile 2 ½ inches long. (These are placed in the bottom of
the bucket to support the lid-separator
4) Drill one ¾ inch hole with a drill bit 2 inches above the
bottom of the 5-gallon bucket.
5) Cut a 6-inch piece of ½ inch (inside diameter) cleara
snug fit, and insert it into the hole. tubing will sit directly below the
separator. ve screw through the tubing (inside the bucket)1 inch from the
7) Cut an “X” with a knife or razor into the shoulder of a
1-gallon milk jug. Insert the end of the tubing into the milk jug and raise
the bucket 8 inches by setting it up on a cinder block or bricks.
permission from University of Maryland