Giving gifts by interest isn't always as easy as it sounds. So often the person has just about everything they want in that category, and so more stuff in that area is hard to find. They either have a better one or don't want it most of the time. Fortunately, sometimes you can get around that, especially for gardeners. You just have to figure it out.
The obvious gift for a gardener is a plant. The right plant depends on what type of gardening they enjoy. Some strongly prefer roses, for example.
If you want to give the gift of a rose bush to a rose lover, you will want to pick very carefully. Look at the varieties the person is growing right now. If there's a strong preference for a particular type or color, that is something you will want to keep in mind. Maybe you can find a somewhat unusual rose bush for them that would go well in the garden.
Bonsai would be another option, rather than giving something meant to be planted outside. There are many beautiful varieties of bonsai out there, from trees to bushes to flowering plants. Bonsai are often kept indoors, and certainly aren't meant to be planted in the ground.
That goes against the very definition of bonsai. So as a way to bring just a bit of the garden indoors in an elegant way, bonsai may be perfect. When giving plants, paying attention to what type of garden is being grown is key. Succulents or cacti for someone who loves to grow them, bulbs for the flower gardener and so forth. Of course, tools and gardening books may be given as well. The challenge is in knowing what is needed.
For books, if you can spy on their shelves you can figure out what types of gardening books they already have. No point in buying one they already own or not on a topic they enjoy, after all. Similarly, you'll want to check out their tool selection before trying to buy gardening tools.
If you want your gift to really stand out, think about a bench that would look nice in the garden. The best material and design will depend on the type of garden and what else is in there. Many people love wooden benches, even fairly simple ones, but others do prefer a classic looking concrete bench. Your favorite gardener may not be the easiest person to shop for sometimes, so give yourself enough shopping time to allow inspiration to strike. You never know when the idea for the perfect gift may appear.
Stephanie Foster runs http://www.assortedgiftideas.com/ where she gives gift suggestions. Check her website for more gift ideas for gardeners.