1. Ask Them Directly
So, if you are considering buying a gift for the greenhouse or grow room, your best bet for success is to not let it be a surprise. Ask them what they have had their eye on, and then go get it for them. Much better to have no surprises and a happy gift receiver than an awkward unwrapping.
2. Give Knowledge
3. If Buying a Product, Do Your Research
You can go down to the local Hydro shop and ask them for their expert advice if you know what kind of gift they are looking for. If you're lucky, they might even know the person who you're giving the gift to and will be able to give a very specific recommendation!