I've got a large forest border that I wood like to fill with some nice color. I've started by clearing most of the weed trees to about 15-20' from my grass border. This also goes to the trunks of some of the very large 150-200 year old oaks. Now I would like to fill this area in with a nice natural forest type look but with colorful trees unlike the ones I removed. Most of the ground is covered with ferns and other native ground cover type plants. I've already started adding some trees that should fair well in this mostly shady forest boarder. Mostly redbuds, dogwoods and maples. Now I have plenty of choices with all the cultivars of japanese maples to fill the gaps but I'm just not sure how close they can be planted without looking crowded. I don't mind the over laping of branches with a nice contrast of colors but I don't want them too close where it will hurt the health of the trees. The problem with japanese maples is they grow fairly large but grow so slow. It looks so bare right now because most of the trees I've planted are so young. I am hoping I can get away with planting some more varieties to help fill in the gaps but wanted to see if this is a bad idea because I'm always reading on here to plant with the full size of the tree in mind. Do any of you have advice on this type of planting or even better, pictures of these maples planted fairly close growing together. Right now I think my closest planting is maybe 15' apart but I feel like it will take forever to fill in this space. Here is a picture of part of the border I'm talking about. Thanks for any help!