Using colour in the design of your outdoor space is one of the most difficult gardening tasks to master. Compared to choosing colours for the interior of your home, deciding for the garden is even more difficult. Colours change from season to season and year to year as plants mature. Just imagine how hard it would be if your walls and furniture kept changing colour with the seasons. Successful colour selection will help you turn a collection of plants into a garden that is a work of art.

I don't presume to be an expert on colour, but I know some of the things that need to be considered. Lucky for us, there is no right or wrong and any rules we might come across are made to be broken. You only have to be true to your own ideas, making your garden an expression of your own personality.

When you are thinking about colours for the garden, you should also consider the colours of the exterior of your home as well as objects in the garden and colours of the vegetation. Don't forget that green is a colour too. Beautiful Japanese-style gardens have been created out of various shades of green with only small splashes of colour from seasonal flowers.

It is a common desire among gardeners to have colour throughout the growing season, but it may be unrealistic to expect an entire season from any one garden bed. Invariably you end up with large holes left where perennials have finished blooming.

Colours elicit emotional responses in us. Choice of colours revolves around a colour wheel in which colours are arranged in the order of the rainbow (red, orange, yellow, green, blue, violet, and back to red). On one side of the wheel are the warm colours of red, orange and yellow. These colours jump out at us and give excitement. The opposite side of the wheel has the cool colours of green, blue and violet. These colours have a calming effect in the garden and tend to look farther away. Plants with grey leaves also make us feel calm.

Some very effective garden designs involve using colours that are next to each other on the colour wheel. So red and orange work together as do yellow and green.

Another approach is to use colours directly across from each other on the colour wheel. This is why the Christmas colours of green and red work well together and why violet and yellow is a great combination.

A third effective strategy is to use three colours that form a triangle on the colour wheel. For example the primary colours of red, yellow and blue work well together and give a lot of colour yet feel balanced.

While it is difficult to pull off, a few gardens are created with various shades of one colour such as an all red garden or an all white garden.

You need to think about some of the same things that an artist thinks about when painting. Garden design involves balance. First of all, larger masses of colour are more effective than small groups or single plants. When trying to come up with a pleasing composition, it helps to repeat some design elements. This holds the garden together so that it looks like one part of the garden belongs to another. But too much repetition can be boring so it is also good to have variety. On the other hand, too much variety looks chaotic. It is good to have some things in your garden that stand out from all the others as focal points to where the eye is drawn. On the other hand too much emphasis on one thing at the expense of all others causes the design to feel unbalanced. Having some elements out of scale with others can also feel unbalanced. You will probably know instinctively when it "feels" right for you.

Lighter or darker versions of colours are also possible. For example, the lighter version of red is pink while the darker version of red is brown. The dark leaves of the purple smoke bush will go well with violet-coloured flowers as well as with the pink or red flowers because, even though these colours are light or dark, they all come from adjacent colours on the colour wheel.

If you have a shady spot dark spot, colour can be used to brighten it. Pure white or very light colours stand out well in the shade or in the evening. A variegated or light green hosta can do wonders for a dark corner.

The possibilities for use of colours in the garden are endless but unless you can imagine it all in your head, you are going to have to use trial and error like the rest of us.

Gary Westlake is a Master Gardener. Have your garden questions answered by visiting our website at www.peterboroughmg.ca or our garden phone hotline at 705-741-4905.