I have a number of lily of the valley and grape hyacinths that I’m looking to transplant elsewhere in my garden. Is it ok to plant either of them at the base of my Japanese maple? If so, should I maintain any specific distance between the flowers and the trunk of the maple?
Yes, planting lily-of-the-valley (Convallaria) and grape hyacinths (Muscari) should be fine in that location. However, remember that lily-of-the-valley can be quite aggressive and prolific, growing where it wants to grow, no matter how far from the trunk you originally plant it.
As the roots of Japanese maples (Acer palmatum or A. japonica) are quite shallow, when transplanting your plants, try not to disturb the roots too much by digging as small a hole as possible for each plant, rather than digging up a large area. Also, always remember to ‘feed’ the soil around your tree with compost so that the groundcover does not absorb all the nutrients that the maple will require.
One idea you may also want to consider for the grape hyacinths is to plant a Hosta just in front of the bulbs so that as the latter die down after flowering in the spring, the hosta leaves will grow to cover them.
Good luck with your garden