Firstly, I’ve got to say, I know a lot of people who take birthdays/anniversaries etc very seriously. I’m glad DH and I were on the same page and didn’t! Lots to consider in the OP too - partners, so more than gf/bf, but no mention of ages. Did he take time off work to tackle this job? Is he retired? What’s his track record with gifts? Does he struggle to find things? Generous in spirit and deed, or a cheapskate who could but won’t spend money? There’s often advice here to offer one’s time to others, rather than present gifts which will end up in charity shops.
From another thread, gardeners are charging from £25 to £50 an hour, so think how much money was saved.
Like others, I think he’s done a grand job and should be thanked - even rewarded by a meal out, or small gift - new gardening gloves or handcream.
In the ‘70’s, DH’s BiL bought his wife a brand new car for Christmas. A pale green, Vauxhall Chevette, adorned with an enormous bow, secreted in the garage on 🎄Eve. ‘Til the day she died, MinL complained that he hadn’t even ‘left a box of chocolates inside!’
You can’t please all the people all the time.