Choosing Containers for Container Gardening

wooden container
Wooden Planter, chema.foces, Flickr

Choosing pots that meet your aesthetic and practical gardening requirements is essential to creating a beautiful, productive, low-maintenance container garden. The following is a summary of the advantages and disadvantages of various types of containers for garden plants.

Wooden Containers for Plants

Most commonly available in Versailles boxes and rustic half barrels, wood provides a number of natural advantages, including:

    • Frost resistance to protect against temperature extremes
    • Better water-retention than terra-cotta

However, a major disadvantage of wood is its tendency to rot. To prevent or slow the rotting of wooden containers:

    • Choose containers made from cedar, a naturally rot-resistant wood.
    • Use mini-supports, stone, or brick to prevent containers from sitting directly on the ground.
    • Use a natural, non-toxic wood stain that won’t leach chemicals into your plants.
    • Use a metal or plastic liner.
    • Rub the interior and exterior of the container with linseed oil.

Pressure-treated wood and other toxic chemical coatings should be avoided, particularly for containers that will house food plants.

Stone Planters

Stone Planter
Stone Planter, Horia Varlan, Flickr

Stone planters require no maintenance, and they are actually improved with age and weathering. This weathering process can be sped up by spraying liquid fertilizer or painting yogurt onto the pot to encourage algae and lichen growth. Additional benefits of stone include:

    • Strength
    • Durability
    • A non-porous texture, which reduces the likelihood of plants drying out

The main disadvantage of stone is its weight, which makes it difficult to move around. It also has a rustic look, and thus will clash with certain landscaping materials such as polished marble.

In addition, alternative stone-based materials such as limestone and concrete may cause a more alkaline soil environment by leaching lime into the dirt.

Terra-Cotta Plant and Flower Pots

terra cotta pots
Terra Cotta Pots, Felixco, Inc., FreeDigitalPhotos.net

Baked earth clay is a versatile container material, with pots available in a wide array of shapes, sizes, and prices. Terra-cotta pots are available in natural earth colours ranging from pale ochre to deep, earthy reds, depending on the region where the pot was made, and they may also be glazed in various colours, with blue being particularly popular. Like stone, unglazed terra-cotta pots are enhanced with weathering and age as nutrients leach through their porous surfaces, triggering the growth of algae, and these pots are always attractive and stylish.

Clay pots enable air to reach plant roots and prevent plants from becoming waterlogged (which can lead to root rot). However, there are a few disadvantages to clay pots, particularly their fragility. To care for terra-cotta pots:

    • Soak pots in water before planting.
    • Purchase frost-proof terra-cotta pots or bring pots indoors during the winter.
    • Line the insides of terracotta pots with plastic sheeting (be sure to poke some drainage holes in the plastic) to reduce the risk of cracking due to frost.
    • Avoid planting varieties that have very large, tough roots (such as agapanthus) in clay pots, as they may break through the clay.

Terra-cotta pots are vulnerable to frost and shouldn’t be used for winter crops. When not in use, store clay pots either on their sides or upside down, and move them to a dry place during winter to prevent cracking.

Terra-cotta pots tend to be very heavy when filled with soil, so large clay pots are not the best choice for balconies, or any space where they must be moved regularly.

If using terra-cotta pots, keep in mind that soil will dry out more quickly, so more frequent watering is usually required.

Metal Planters

Metal plant containers are available in a wide variety of finishes including coloured, polished, and matt. Frost-proof and tough, they are easy to maintain and many are quite beautiful. However, they do have a couple of disadvantages:

    • They eventually lose their shine due to oxidization.
    • They can be dented or scratched with rough handling.
    • They can heat up if placed in sunny locations, causing plant roots to scorch.
    • They can rust over time, so a drip tray should be used to guard against rust stains on the surface where the container sits.
    • They can reflect blinding sunbeams at certain angles.

Zinc is a good material for metal plant containers because it won’t become dull, show watermarks, or rust easily. Stainless steel also doesn’t rust, though fertilizer may cause corrosion unless a plastic liner is used.

Plastic Plant Containers

plastic pots
Plastic Planters, Simon Howden, FreeDigitalPhotos.net

Lightweight and versatile, plastic containers are particularly good for roof decks and balconies. Available in a broad array of styles, they can simulate stone or metal at a much lower cost.

Plastic containers can be used on their own or as inserts in more expensive containers that would require more maintenance if used directly as planters.

Grow Bags

grow bag
Grow Bag, cultivatorscorner/Trisha Dingillo, Flickr

Grow bags are space-efficient both for hanging and for storage because they’re collapsible. They enable people who don’t have yards or even balconies to grow strawberries, tomatoes, peppers, herbs, and other produce because they can be hung in sunny windows. Advantages of grow bags include:

    • Greater moisture retention, which saves time on watering
    • Versatility and space efficiency because they can be used in a wider variety of spaces, including vertical spaces when hung
    • Cost-savings due to their relatively low price compared to many other container types
    • Less mess and lower maintenance requirements
    • Reduced risk for pests, soil-borne diseases, and weed growth

Grow bags are a particularly good solution for the urban gardener who must work within a small space.

Alternative Plant Containers

With a little creativity, a variety of items can become attractive planters, including:

    • Wheelbarrows
    • Baking pans or metal mop buckets with drainage holes
    • Old rowing boats
    • Large seashells
    • Hollowed-out tree stumps or trunks
    • Lined wicker or wooden baskets

Although many sites recommend using rubber tires as inexpensive plant containers, these can leach toxic chemicals. For the same reason, you should avoid using any container with toxic paint or other coatings.

When choosing a container, be sure to select one with drainage holes (or a container that you can drill drainage holes into if it doesn’t have any). Also, keep in mind that darker colours capture and retain more heat, so they may be better for partial or full-shade plants, whereas lighter colours are better for full-sun locations.

For more gardening articles, visit the main Gardening page.

References:

    • Container Gardening Guide. (2011). “Choosing Containers for Container Gardening – Match Garden Containers to Your Landscape and Home Style.” Container-Gardening-Guide.com.
    • Harrison, J.K., & Smith, M. (2009). The Container Gardener’s Bible. London: Quarto Publishing Plc.

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