Considering the popularity of the sport, it's inevitable. A plant for the garden seems like the obvious choice but, even if the climate allows, is tricky.
Most gardeners like to pick out their own plants.
Another easy way out is a gift certificate to a nursery. But opening an envelope won't earn you as many points as something you've put some thought and effort into. If you're looking for a gift that's guaranteed to be well received, consider a pair of Felco pruners . These Swiss-made cutters are revered among gardeners. Do be aware that the Felco pruners vary in price.