Marin Master Gardeners
University of California
Marin Master Gardeners

Short on space? Containers to the rescue...

Container Gardening: a great way to expand your garden

Succulents are excellent container plants
Succulents are excellent container plants
By Kathy Reiffenstein

Just because you live in a condo with a long, narrow, bowling alley-shaped deck or an apartment with a postage stamp sized balcony or patio, that's no excuse not to garden! In fact, these outdoor spaces, somewhat removed from "terra firma," provide a wonderful opportunity to enjoy nature. Containers in all shapes and sizes allow you to cultivate flowers, herbs, and fresh veggies in the smallest of spaces.

Before getting down to the digging and planting, take some time to think about what sort of a look and feel you want to achieve in your garden. Do you simply want some color that you can enjoy from inside? Do you want a quiet oasis, where you can sit and read among sweet scents and lush greenery? Do you want the look of an English garden, filled with all shapes and sizes of flowers, overflowing their containers, with barely enough room to squeeze by? Do you want the minimalism and simple elegance of a Japanese garden? Or do you want a formal look, with neat plants and classic containers, all highly organized in symmetrical arrangements? Answers to these questions will make for a much more productive trip to the nursery.

Another bit of homework that you need to do before you get started is to observe the weather and the microclimate(s) on your deck or balcony. How much sun do you get a day? Is it morning or afternoon sun? Are there shady spots? For how long? How much wind do you get? Is it generally warm or cool? It is critical that you know the weather conditions in your garden or it is very likely that you will end up with the wrong plants. Although one huge benefit of a container garden is that you can move the pots to take advantage of shifting sun or shade angles, you still want to maximize your success by choosing the best possible plant(s) for your specific location.

Containers
Virtually anything can be used as a planter, as long as it has drainage holes and can survive outside. If you fall in love with a container that doesn't have drainage holes, you can drill your own (use an electric drill with a masonry bit for clay and concrete) or use it as an outer, decorative pot, and put a smaller draining planter inside (don't let the inner pot sit in water; empty excess water).

Planters run the gamut from traditional terra cotta to wood to ceramic to plastic to concrete to even whimsical items such as an old pail, a watering can or an old rubber boot. Your imagination's the limit!

Keep your style in mind as you consider various containers. An old rubber boot probably won't really fit in your formal garden, unless you are looking to add an amusing note of whimsy. Most nurseries and home improvement stores will stock the standard plastic terra cotta look-alike, genuine terra cotta, and ceramic. To find other, more unusual containers, search out garage sales, antique shops or your parents' attic. Also think about how well the container will complement the plant you're putting in it. A good rule to follow is that if the container is quite elaborate or bold in design, keep the planting simple; if the pot is simple and basic, you can go for a more dramatic plant.

Aside from the look, different materials hold water differently. Keep this in mind as you think about how much attention you'll pay your garden. Terra cotta and untreated wood are the most porous; they will allow air to get to the roots, and water and fertilizer to move out through the container walls. But they will require frequent watering since they will dry out quickly. Glazed ceramic and plastic containers tend to retain moisture so you need to be careful that you don't overwater or over-fertilize.

No matter what kind of container you choose, before planting, clean it out thoroughly with household bleach and water (1 part bleach to 10 parts water). Also, be sure to raise your container up off the ground once it's planted. It only needs to be an inch or so off the ground to promote good drainage and air circulation, as well as prevent water stains on decks and balconies. You can put bricks or blocks of wood beneath your pots (be sure to position them so that air can reach the drainage hole) or you can purchase decorative feet at nurseries. Another inexpensive solution is to purchase the tiny, three-inch wide pot saucers at the nursery and turn them upside down under your plant. Three saucers provide a stable perch for most pots.

Choosing Plants
Almost any plant will be happy in a container, as long as the container is big enough and the growing conditions are appropriate. However, a container does restrict a plant and makes it almost wholly dependent on you for its water and nutrients. So, it is a good idea to select plants that have certain characteristics that are well suited to living in a container:

  • naturally compact growth habit
  • attractive foliage
  • flowers for a long time (or repeat flowers)
  • isn't a water guzzler

Annuals, perennials, grasses, bulbs, shrubs, vines, herbs, and veggies all do well in containers. If you're buying perennials, don't fill the pot because they'll grow and, before you know it, you'll have to repot. Instead, add some colorful annuals to fill in around perennials until they fill out.

Consider using color and texture in a container for added impact. Mass a number of the same plants or combine several different plants of the same color family for drama; for example, fill up a container with trailing purple-blue convolvulus (Convolvulus sabatius), or pair up orangey-yellow black-eyed susans (Rudbeckia fulgida ‘Goldsturm’) and lemon yellow coreopsis (Coreopsis verticillata ‘Moonbeam’). Match up a cool pastel plant with gray-green grasses or foliage, for example, lavender or pink scabiosa (Scabiosa caucasica) with lambs ears (Stachys byzantina). Or mix plants with opposite colors on the color wheel, for example, purple New England asters (Aster novae-angliae ‘Purple Dome’) and yellow marigolds (Tagetes).

Soil
The right growing medium is critical to the success of your plants. It is best to use a good organic potting soil from your nursery, as regular garden soil is way too dense to use in containers. Potting soil is lighter, fast-draining and contains numerous nutrients and mineral matter; if you choose potting soil specially formulated for containers, you won't need to add any other ingredients. Place a piece of shade cloth or plastic mesh over the drainage hole(s) so the soil won't run out each time you water. Be sure to thoroughly water the soil once you've put it into the container and before you plant.

Care
Now that you have chosen your plants, matched them up with containers that will show off their beauty, and artfully arranged them, it’s time to focus on taking care of them. Care of a container garden is not all that different from an in-ground garden, except that plants in containers are almost completely reliant on you for their moisture and nutrients.

Watering
Watering your pots faithfully is the most important aspect of container gardening. Because your plants are confined to pots, they can't draw as much moisture from the surrounding soil as in-ground plants; therefore, they tend to need more frequent watering. Check the moisture level of your plants often -- the easiest way is to stick your finger in the pot. If the top inch of soil feels dry, you should water. Lightweight potting soil, terra cotta containers, and warm or windy weather all tend to make your plants dry out more quickly. Check the moisture requirements for each of your plants, as some plants prefer constantly moist soil, while others can go dry between waterings. Be sure to mulch, using bark, straw, cocoa bean hulls or almond shells; this will prevent the soil from drying out and, if the mulch is organic, it will add some nutrients to the soil as it breaks down.

When you water your containers, give them a good drenching. When water runs freely from the drainage hole(s), you'll know you've saturated the soil. If you have saucers under your plants, be sure to empty them once the water has drained through or the soil will stay too soggy.

If your container garden is not too large, it is a good idea to water everything by hand. That way, you can ensure that each plant gets exactly the amount of water it needs, and you can check for insects and diseases at the same time. A large number of pots or a too busy gardener necessitate a drip irrigation system to ensure that your containers are adequately and consistently watered.

Fertilizing
The only nutrients your container plants are going to get are the ones you give them, so it is a good idea to fertilize when the plants are actively growing from spring though fall. That said, be wary of over-fertilizing (particularly with high nitrogen fertilizers), which causes rapid growth and in turn, tends to attract pests such as aphids.

Read and follow fertilizer package directions, although it may be wise to give your plants a half-strength dose and see how they do, thus minimizing the chances of over-fertilizing. A slow release fertilizer (vs. a liquid fertilizer) will allow the plant to take up what it needs over a period of time, rather than giving it a concentrated "hit" all at once. Fertilizers are an area where you really need to talk with your nursery professional and experiment in your own garden to see what works best for you.

Pest Management
Pests and diseases will be less frequent visitors to your container garden if you keep your plants healthy and happy -- give them the right growing conditions and water and feed them adequately. Deadhead your plants frequently and clean up any fallen debris in the pots; don't over-fertilize; check regularly for initial signs of any problem.

If you do find some insects on your plants, treat immediately and use the least toxic method of control possible: hose off aphids with a strong stream of water; hand-pick slugs and snails and dispose of them; hang yellow sticky strips to catch whiteflies; plant yarrow, dill, cosmos, and alyssum to attract beneficial insects (like lady beetles) which eat the harmful insects.

Pruning
To ensure that your plants produce as many flowers as possible, cut or pinch off (deadhead) spent blooms regularly. Some plants, such as roses, need to be pruned each year, generally in January. Let the look of your plant be the guide as to whether or not you need to prune -- if the plant appears straggly or is producing stunted-looking flowers or fruit, prune it back by about a third to encourage new growth. Most plants can be pruned in the fall, after the growing season.

Finishing Touches
To put the finishing touches on your garden, add a few decorative elements intermingled with the plants. Consider small, whimsical concrete statues or painted garden signs that proclaim, "A Garden is the Happiest Place on Earth.”


edited by Marie Narlock and Anne Wick

Webmaster Email: banielsen@ucanr.edu