The best gift of all for the gardener you love:
A membership at the local botanical garden -- a gift that will give someone pleasure for months to come.
If there's not a great local garden in your area, then a membership to The Garden Conservancy
Useful, great garden gifts. If there's not time to order online, you should be able to pick up something very similar at your local garden center.
Various sizes and prices, but all do a great job in the garden.
Every gardener should have one or two.
Another tool I'd never be without. Good for planting, transplanting, weeding planting bulbs and small plants ... it will also cut roots. If you have one of these, you won't need much else.
A basket full of gardening essentials ... maybe for that Millennial couple just getting started with the new house.
Put up a wreath of hellebores to get yourself in the mood for spring ... this can also be used to show off dahlias, pansies, and other small flowers. Terracotta ring.
Great way to hide those unsightly downspouts ... can't think of anything better than a colorful clematis or another light-weight climber that would cover the ugly tubes that adorn so many a residence.