When you buy a plant, make sure it is healthy. The leaves and branches should be a good color and shape, not discolored or distorted (unless the plant variety dictates this). There should be a good collection of roots, with not much loose potting mixture, but the plant should not be potbound. When a plant is potbound, no potting mixture is visible and the roots wind tightly around each other.

Shop prepared:

•     Don’t go to the garden store without a list of what you want to buy.
•     Make a simple plan of your garden; draw rough outline shapes to show individual specimens and groups of plants.
•     In small areas you may have space for only one tree and a few key shrubs, and this makes it doubly important you choose wisely.

Where to shop:

•     Garden Centers/Superstores: These places are the department stores of the gardening world, stocking everything from plants, seeds and potting mixture to tools and garden furniture.The great advantage of buying at a garden center is that you can seee the plants in leaf and in flower, season by season.
•     Specialty Nurseries: These are usually run by enthusiasts by enthusiasts, and they often specialize in a particular plant type.
•     Society, Garden Club and Public Garden Sales: Interesting cuttings, divisions, or seed-raised plants, often from club members’ collections or found in the public garden, may be had for good prices. These sales offer the chance to acquire the rare and unusual.

—from The Horticulture Gardener's Guide to Plants for Small Spaces by Clive Lane

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