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Pots and planters are great on patios and decks, or rooftops and balconies, or just to use as pots of colour to set into the garden when you need some extra bloom!

Choosing a container:

Suitable containers can be of any size and manufactured from many materials but consideration must be given to the size of the plants, as well as the required amount of soil medium and the need for drainage. Most plants require good drainage, so drainage holes are essential to prevent root damage or death. Excess water must be able to drain out, or you'll literally drown your plants. Look for containers with good drainage holes. However, remember that some plants, such as bog, pondside or water plants, require moist or wet soils or water to float in.

You can improve drainage and use less soil mix (of particular concern when using large containers) by putting stones, broken shards of pots, or even scrunched up empty cell packs in the bottom. Try self-watering containers designed to raise the soil and roots above the water level of the saucer and then provide a "wicking-system" to bring the water up from below.

The right soil mix:

Choose a mix that is lightweight - especially for hanging baskets. Soilless mixes (a combination of peat moss, perlite and vermiculite) have a number of advantages. They are convenient to use, lightweight and weed free but are low in plant nutrient. Small amounts of weed free compost or well-rotted manure can be added initially to add nutrients. Add bone and blood meal or granular slow release fertilizer. Always work with your potting mixture slightly damp or wet.

Polymer gels are crystals that form a gel when mixed with water. These crystals will help to prevent your pots from drying out so quickly in the heat of the summer. Bags of potting mixes are available with this already included. Garden centres may have other products that can be added to the soilmix that will help to retain water (e.g. sponge products).

Design Elements:

• Location: Consider where the planter will be located - sun or shade.
• Plant choices: Select a mix of annuals, herbs, perennials, shrubs or vegetables suitable to the growing conditions.
• Colour: Consider colour of the plants (blooms and leaves) and container.
• Texture: Consider the texture of both the mixture of plants and the container.
• Shape/size: Consider the shape and size of the plants (leaf size, form, height and width of plants) as well as the dimensions of the container.
• Balance: Consider the size of your container and the mature height of your plants. Plants should not be much more than 2 times the height of the container.
• Number of containers: Design experts recommend using an odd number of containers in a given location instead of an even number.

Planting Your Container:

Ensure that the container is clean (particularly if used before). Soak porous containers before filling them. Choose plants that are suitable for growing conditions (e.g. choose plants that are drought tolerant for containers in extremely hot and dry conditions; choose shade plants for containers in shade conditions).

Water plants well before you begin planting to help the soil stick to the roots. Remove some root if necessary to fit into the container. Start with a plant for height in centre. You may have to use your imagination to visualize the mature size of the plant - read the label! Next, add medium height plants around in odd numbers. Finally, add trailing plants (closer to the edge) and more soil to secure all plants. Water thoroughly.

Consider using a mixture of plants that will provide colour and/or form (both leaf and bloom) during the entire growing season. Consider using plants that provide form during the winter months (e.g. ornamental grasses).

Maintaining Your Container:

Pinch off the ends of the shoots and any flowers or flower buds after planting, or when the plant is still young and leggy, to encourage bushiness and the development of many more flowers.

The most important job requirement for maintaining a planted container is to water consistently to keep plants looking healthy. Do not let your container completely dry out. A watering regimen will depend on the location and size of the container as well as growing conditions. For example, containers in windy, hot conditions will dry out more quickly than similar sized ones in protected, partial-shade conditions. Small containers will generally require water more frequently than larger containers. Remember that water will evaporate faster in some containers (e.g. porous ones) than in others (e.g. plastic). The need for water will also depend on the species planted.

Containers often need water each day. In the heat of the summer you may have to water small containers several times a day. Water thoroughly but gently, until water runs out the drainage holes.

Once the plants start growing fertilizer must be provided. At a minimum, every few weeks feed your plants with a balanced, water-soluble fertilizer. Plants in outside containers require fertilizing more frequently because of rapid plant growth and because frequent watering will cause nutrients to leach out of the soil. Always wet the soil before adding fertilizer solution to avoid burning dry roots. Be careful to follow instructions on the label of the fertilizer.

Deadhead blossoms by pinching off the dead blooms. This encourages more flowers. Annuals have a job to do - produce flowers and set seed to reproduce. If you remove the flowers before the seed is formed, the plant must produce more flowers to do its job!

Advantages of Container Gardening:

• Using containers does not require a garden area.
• Containers can used to bring beauty to a large variety of areas (e.g. hanging baskets, attached to a trellis, on balconies, sidewalks, driveways, patios, windows or even rooftops.
• Plants can be grown in containers that are not suitable for the your garden conditions (e.g. sandy soil, heavy clay, damp conditions).
• Container plants can easily be moved indoors at the end of the growing season.
• Container plants are protected from some pests (e.g. slugs, snails).
• Containers can be chosen as a design element in the garden to reflect the 'aesthetics' of the garden (e.g. wood for casual gardens or wrought iron for more formal gardens).
• Containers can be used to meet a variety of design goals (e.g. to position 'moveable' groupings of special colour or texture in your garden, mask unsightly areas, accentuate functional areas (e.g. position fragrant plants near a outdoor dining area).
• Containers can be planted and maintained by persons who have limited physical abilities. There is no need to dig and use heavy garden equipment. Planting and maintenance can be done using hand tools.

Specific Considerations:

Always consider how the process of watering could impact nearby surroundings (e.g. ease of using hoses or watering cans or the possibility of water damage from dripping containers).

References:

The Toronto Botanical Garden Weston Family Library is an excellent source for horticultural information.

Hillier, Malcolm. Container Gardening Through The Year. New York, U. S. A.: Dorling Kindersley Publishing, 1991.

Hessayon, Dr. D.G. The New Bedding Plant Expert. London, England: Expert Books (div. of Transworld Publishers Ltd.), 1997.

Factsheets are produced by the Toronto Master Gardeners in association with the Toronto Botanical Garden. They provide introductory information about a broad range of horticultural topics and are intended for personal use and study purposes. Should your gardening group or organization wish to use multiple copies we ask that you inform the Toronto Botanical Garden at info@torontobotanicalgarden.ca.

Date revised: January 8, 2006