Gareth Carter: Container plants a great opportunity, says Whanganui garden centre

INDOOR SOLUTION: Containers are great for people who live in townhouses or flats.

Growing plants in containers presents gardeners with endless opportunities to express their imagination and flair.

It is great for people who live in townhouses, flats or home units. They can be used to soften and beautify outdoor living areas and entrance ways or create a focal point in the garden.

One of the best things about container grown plants is they can be moved from one place to another provided they are not too heavy to handle. This way you can give plants a suitable microclimate to display and show them off when they are at their best.

Choices include a fragrant plant by the front door, a cheerful bowl of spring bulbs or an immaculate piece of topiary. There are also many types of edible plants that can be grown in pots and containers.

You can grow almost any plant in a container, so whether you would like to brighten up your patio, or grow an edible feast, it's simply a matter of choosing suitable plants for the particular conditions. Once you have decided which particular look or style appeals, the next question is what sort of pot or container? There is a wide range available to choose from.

Creative containers - there are many objects, which have outgrown their original use, that are ideal containers for growing plants. Old troughs, cooking pots, coppers, wheelbarrows, baths, beach driftwood and pumice etc are often used. Even old disused boots and gumboots are seen occasionally supporting herbs or other small plants.

If providing drainage holes presents a problem you can use plastic pots inside, raised up on a small amount of gravel or chip stone and keep a check that they don't get waterlogged.

Situation and soilTo grow plants successfully in containers you must select the right plant for your situation. Sunlight, shade and wind are all important factors that will influence your plant choice.

Sun-loving plants such as vegetables require at least 4-5 hours sunshine each day so check the site before selecting your plants. All containers must have good drainage; pots and tubs should have one or several drainage holes 1-2cm in diameter.

Ordinary garden soil is unsuitable for pots because it does not drain well and can set hard. Potting mixes available from garden centres, etc, are the best medium to use for growing plants in pots. A general rule is you get what you pay for, a cheaper potting mix will often have a poor structure that breaks down or degenerates quickly.

There is significant science that has gone into the development of potting mixes. The best potting mixes will hold their structure for a long time providing a high level of what's known as AFP, or Air Filled Porosity.

AFP is the volume of mix that is filled with air at a given time. A low AFP indicated poor aeration and restricted drainage. We often consider the amount of sun that a plant receives, to get good results the plant needs to have a good potting mix to grow in.

I have done a number of trials and found that the structure of the potting mix is more significant to plant growth than the amount of fertiliser (although this is also important) that is in the potting mix. When potting, the final soil level should be a little way below the rim of the container. When watering fill this space slowly with water until it drains from the holes in the bottom of the container. A mulch of bark chip or nuggets helps reduce evaporation and cools the surface soil.

Good drainage and frequent watering causes a loss of plant nutrient. Regular small amounts of fertiliser are needed to keep plants growing strongly. Always apply fertilisers to moist soil to avoid burning young roots. Liquid fertiliser such as ICan Fast Food are suitable for regular liquid feeds.

Slow acting fertilisers such as Novatec or Osmocote provide nutrients over a long period. Always use fertilisers following the manufacturer's instructions on the label. Too much fertiliser can have a burning effect on plants especially if the potting mix dries out.

Happy gardening!

■Gareth Carter is general manager of Springvale Garden Centre