Q. Would Jewish law allow me to kneel while gardening?
A. I don’t think there is any problem. Various rabbis I asked agreed with me. I thought of a person kneeling before the Queen to receive a knighthood, and asked a British rabbi his views. Not only did he find no objection, but he said that one does not kneel on the ground but on an ornate stool, is not kneeling to a deity, and it is all a formality. Several orthodox rabbis have been knighted, and presumably they all followed the usual procedure without qualms.
No-one is likely to misconstrue kneeling in the garden or at Buckingham Palace as a form of worship, so you can continue to do your gardening – but take care of your knees.