A garden is more than a random collection of plants. It is a design that takes effort to put together. The designer needs to pay attention to the way the plants are grouped together. These groupings need to be effective and planned out. Plan your garden to make use of your limited space. The garden space needs to have the tallest plants at the back of the space with the smaller perennials near the front. Long blooming perennials can bring extended periods of interest to your small garden.
Measure the garden space. It may help to picture the garden space by marking it off with a rope or a hose.
Sketch your garden layout on a piece of graph paper. Try to draw it to scale to keep your size in perspective. A good measure is 1 inch for every 2 feet of garden space. The scale for larger spaces is 1 inch for every 4 feet of garden.
Sketch in existing structures and any plants that you plan to keep. When drawing in your plants, draw in mature size of your plants. This will prevent overcrowding later.
Start by working on the back edge of the diagram. Use coloured pencils to add the colour of the flowers to the plants. The plant choices in this section should be tall. Pick backbone perennials that have long lasting blooms. Pick complementary flower colours that do not clash or cause a riot to your visual senses.
Draw in shorter plants between the tall plants and edging area. They should be grouped together in clumps of three, five or seven. This increases the effect of colour in your garden. Work on the texture at this time. Do not place all the same flower shape in one area. Place sharp, spiky flowers next to the round one to add contrast to your garden.
Finish your garden design by including edging plants. These perennials should be short or sprawling. Geraniums make a great border because they have an extended blooming period and will fill in any gaps in your design.
When designing an island garden with a walkway all around the area, keep the taller plants in the centre and the shorter ones near the edges. Choose plants that look good while flowering and supply interesting leaf colour while not blooming.
Scattering your plants throughout the space looks uncoordinated and unplanned. Keep your perennials clumped together. Various colours and textures bring a lot of variety, but do not use too many different types of perennials. Repeat patterns several times to make it look like you planned out a theme for your space.