First of all, how do you tell a good nursery from a bad one?

On your first visit, do you get the immediate impression that people are keeping the place clean? A tidy, well-kept nursery means the place is staffed by people who care about what they are doing. Do the plants look upright, well watered, and of good color? Is there a good selection of plants for sale that are suitable for your region?

Don't balk if you see plants that are not well-adapted to your zone. There are gardeners out there who love a challenge, and won't always limit themselves by what they see on the zone map. Even the most ethical nursery will cater to such reckless souls (of which I am one!). Ask questions about basic things and see if the answers make sense for the region in which you garden. (Asking the proper planting time for a plant you've grown successfully is a good test.) If you like the looks of the place and get the feeling the staff is knowledgeable, you've come to the right place.

Now, before you start spending money, decide what you want to plant. This is not to say you can't change the plan if you find something desirable that you hadn't thought of ahead of time, but you can't change a plan until you have one.

If you are planting a flower bed, at least make a rough map showing by location the colors and foliage types you'd like to display. Such a plan need not be too specific; you can fill the bed with whatever happens to be available at the nursery that matches the colors, sizes, and scents you are after.

In addition to this basic plan, make note of the conditions the plants will endure. Knowing such things as how much shade the garden will receive or how well the soil drains will help the nursery staff guide you to plants that have the best chance of thriving where you garden. Such information is vital if you find it necessary to choose a substitute for a plant you put in the plan, but cannot obtain this season.