Container Gardening Basics

Choose the Right Container
Outdoor containers should:

  • Be at least 14-18” across otherwise they can dry out too quickly (indoor containers can be much smaller but will require more frequent watering)
  • Have adequate drainage (holes should be between ½ and 1” across, large pots should have multiple drains)—when planting, cover holes with fine screen, cheesecloth or coffee filters to keep soil from running out of the holes
  • Suit the size of the plant (or plants) that are going into them

Containers come in a variety of shapes and materials, which you choose are a matter of taste, style and how you plan to use it. Learn more about Choosing Containers.

Don’t Scrimp on Soil
Choose a soil mixture that:

  • Drains well so plants don’t get waterlogged
  • Holds enough moisture so plants don’t require constant watering
  • Is organic—everything that goes into the pot goes into the plant and will eventually wind up on your plate
  • Has the right pH—most vegetables prefer a slightly acidic soil (5.5-6.5), however blueberries require an even more acidic soil with a pH of  4.5 to thrive

For vegetables, add extra compost (up to 25%) so your plants have what they need to produce in abundance.

Pick the Right Plants
When selecting individual plants:

  • Size matters—always take into account the mature size of any plant before you put it in a pot, especially if you’re planting trees; make sure you stick with dwarf and/or slow growing varieties so they don’t outgrow their new home too quickly or crowd out other plants
  • Buy big—the larger the individual plant (say, a 1 gallon vs. a 4” pot) the more well-developed the roots
  • Consider the cold—in a container, a plant’s hardiness decreases by about 10 degrees (sometimes more in smaller pots); a plant that may ordinarily handle your winter quite well might not have the same success in a pot

When determining which plants go together:

  • Make sure they have compatible needs in terms of water, sun, soil pH, etc.
  • Coordinate plant heights—include something tall, a few things mid-range, a few more small and of course, some trailers to hang over the edge of the pot
  • Keep the pot’s location and planting design in mind—taller plants may cast shade on lower level sun-lovers or a building may block light from one half of the planter

Water Wisely

  • Keeping your containers appropriately watered is crucial to plant survival. Pots can’t hold as much wateras a planting bed while inadequate drainage may keep water trapped.
  • Check daily in hot weather—when the mercury rises, your plant’s water needs increase, and without the buffer of a large garden bed, to keep them cool and damp, sometimes it takes only hours to permanently damage a heat-sensitive plant
  • Dig deeper—don’t just rely on how the soil looks, dirt dries out fastest at the top of the pot so be sure to stick your finger at least one inch into the soil to test its true moisture content
  • Elevate your pots—putting containers on risers helps water drain and air circulate and protects your patio surface from water damage; you can purchase decorative pot feet in most garden centers, but bricks work just as well
  • Consider irrigation—container watering systems cost some money up front, but they will save you time, worry, and the cost of replacing lost plants; they are also invaluable for vacation care
  • Don’t forget the mulch, it helps retain moisture and helps keep roots cool in hot weather

A Few Other Tips

  • Place a saucer below pots on a wooden deck to prevent the deck boards from rotting
  • Consider placing heavy containers on rolling plant caddies so you can move them more easily—especially helpful in climates where tender plants need to be moved indoors for the winter

 

Choosing Containers

There are so many great things about container gardening. For starters, they fit just about anywhere from a tiny apartment windowsill to a sweeping multi-acre estate. They let you garden where you couldn’t otherwise—on a 5th story balcony, inside an office building, on land that’s soil has been damaged by toxins or overuse. They allow you to move plants around as your moods (or the weather) dictate. And most fun of all, containers come in a wide variety of sizes, styles and materials to suit your personality, architecture and budget.

Here is the low-down on some of the most common container types:

Terra Cotta
Probably what most people think of when they think of planting in pots, terra cotta has been around since ancient times. The signature orange unglazed pottery tends to build a mossy coating over time making it especially well-suited to English country gardens.

Pro: Inexpensive, available most everywhere in a variety of sizes, very well draining, easy and fun to decorate (use non-toxic paints as terra cotta is porous and any chemicals could leach through to your plants)
Con: Heavy, dries out very quickly, susceptible to cracking at freezing temperatures, easy to break

To help terra cotta retain water more efficiently, consider using it as a liner for another decorative pot.

Ceramic

Ceramic pots are a great way to add color to your garden. These days they come in a wide variety of patterns, shapes and hues. Try a bold red accent in an Asian-themed garden, or a rich gold for a Tuscan feel. Make sure they have drainage holes unless you plant to use them for a water garden.

Pro: Retains water well, lots of variety in size, shape, color and design,
Con: Often very expensive, especially in larger sizes, extremely heavy, can shatter in below-freezing temperatures

Cast Concrete
These planters can give an instant old-world feel to any garden, especially when overflowing with ivy or other tumbling vines. Consider adding a single, clean-lined focal piece for a bold modern statement, or flank an entryway with two more traditional containers for a classic look.

Pro: Strong design statement, ages beautifully, hard to damage
Con: Extremely heavy, often expensive, can be affected by severe weather, can break down over time

Because concrete can break down over time and because some concrete products may contain harmful chemicals, make sure it is coated inside and out with a non-toxic sealant.

Wood
From redwood planters on the patio, to a recycled wine barrel full of veggies, wood ads a warm, natural look to any landscape. Because wood is readily available, simple to work with and often inexpensive, you can easily build your own pots to suit your tastes and space.

Pro: Natural, not harmed by cold
Con: Decompose over time, can invite termites if placed directly on soil

If you’re going to place a wine barrel or other wooden planter directly in a planting bed, be sure to place it on brick or cement blocks to prevent contact with the soil.

Plastic

You used to only be able to get plastic pots in a terra cotta color and forest green, but things have changed a lot since those days. Now you can find just about any color, size and shape you can imagine, including pots made to look and feel like ceramic, terra cotta, cast concrete and even wood without all the weight and with a lot more resistance to cold and rot. With so much variety, you can find a plastic container for just about any style of garden you can dream up. Plastic pots are especially well suited for balcony and rooftops gardens where load-bearing may be an issue.

Pro: Lightweight, weather-resistant, retains water well, huge variety in color, size, style and price, work well as liners for other pots
Con: Can tip when planted with top-heavy trees, can be expensive for the more elaborate designs, inexpensive or thin-walled pots can break down or fade with prolonged sun exposure

Use caution when planting trees in plastic pots in high-wind areas, as they can be blown or tipped over fairly easily. Consider securing the tree to a nearby structure where wind is a problem.

Nursery Pots
A subset of the plastic category, nursery pots are the black, terra cotta or green pots that most plants are sold in. While they are not particularly attractive, most gardeners usually have a few lying around in a variety of sizes making them easy to get for little or no money, so if you’re on a budget they can be a great solution.

Pro: Inexpensive or free, lightweight, weather-resistant, retains water well, work well as liners for other pots
Con: Unattractive, can tip when planted with top-heavy trees

Nursery pots are best used as liners for other pots or in places where they can be hidden by foliage.

Every Day Objects
Just about anything that won’t rot when wet and can be drilled for drainage can be used to hold a plant, so get creative. Here are just a few ideas to get you started.

  • Metal trash cans
  • Buckets
  • Pedestal sinks
  • Claw foot tubs
  • Tea pots
  • Rubber boots
  • Empty paint cans (be sure the paint is completely removed)
  • Antique wash basins
  • Get creative!

If you’re going to be growing food plants, make sure your container doesn’t contain toxic materials (lead paint or glaze, for example). If you’re not sure, use a nursery pot as a liner to protect your plant (and your pot).