I know of a few professional gardeners that frequent my nursery and they always charge by the hour. This includes time spent traveling for supplies. They charge from $20.00 to $65.00 per hour. If your talented and hard working you can name your price. Most of these ladies started out by putting up an add at a local store listing their abilities and now have more clients than they can handle. Your time is valuable.

I provide this service as part of my landscaping business. I've done it different ways, but right now I'm charging $25-$35 an hour (depends on the complexity of the job, where the job is, and truthfully if i get a sense that the client will be difficult i charge more!), plus the materials. I mark the materials up by 20%, which simply brings the materials up from wholesale to resale for me.

Make sure to keep track of your time shopping and driving around! Also, if i'm at home and looking through design books or going online to research something or to get ideas, i keep track of that time as well.

If you want some more ideas, feel free to email me! The container business can be a pretty good one as long as you don't undersell yourself and your services because they're "only" containers and not "real" gardens. A lot of people who live in urban areas don't have yards, and they want people like you to provide container gardens on their patios, balconies and decks. Good luck!