Possible gifts may include:
1) An attractive container holding seed packets and a special pair of gardening gloves.
2) New hand tools of rust-proof material with brightly-colored rubber handles to make them easy to hold and almost impossible to lose.
3) Purchase a membership in a national or local gardening society like the American Horticulture Society or the local Rose or Herb Society. Such memberships usually include privileges at famous gardens and arboretums and periodic publications.
4) A special shrub or tree. Our ground never freezes too deeply to plant. Your gardening friend can appreciate your gift all year.
5) Books. Look for relatively newly-published books on subjects of special interest to your friend.
6) Larger tools - the best rake, the perfect shovel, etc.
7) Gardening appliances: Spreaders, tree pruners, hedge trimmers, rototillers, lawn edgers, weed wackers, lawn mowers, or tractors.
8) Travel. Package tours of famous gardens throughout the world are available from many sources. Check with the American Horticulture Society, the Brooklyn Botanical Gardens, the National Arboretum, among others, for tips. This is definitely a "high-end" gift, but if you can afford it, an unforgettable experience for your gardening friend.
9) Gift Certificates at local garden centers (like Betty's). Like they say, you can never go wrong with a gift certificate.