Not too late at all but do it quickly!! "Last frost" date has no bearing on planting or transplanting hardy woody plants - that term is used only in reference to cold sensitive plants like annuals or tender perennials. As a gardener with a lot of Japanese maples, I would not hesitate to move a tree that size at that stage of seasonal development. Your risk factor is about nil.

I am a Japanese Maple lover (transplant) from Wisconsin (SE) who has since live in the Mid-Atlantic and now live in the Pacific NW, a few blocks from Puget Sound. For good web information, the link provided above is an excellent web site, as is "Mountain Maples" in California. U R in Zone 5 I believe, and most Japanese Maples thrive in Zones 7&8, though some will be able to live in your Zone. For purchase, I'd go to the bookstore/library and look at a book or 2 on maples, visit some good web sites, then find out which regional nurseries (i.e. Zone 5) have the best selection of these plants, and make arrangements to actually purchase the plant from a regional nursery that can guarantee the tree will survive in your Zone. Japanese Maples are mountain slope plants from the Mountains of Japan. They like lots of water, good drainage, and sheltered location. L believe a sheltered location is critical--if you can have them near a windbreak (i.e. fence, the house) near the 2 most common prevailing wind directions (probably North & West in Wisconsin), they will do much better. They don't need great soil--just average. During periods of drought (no rain for a week or more), they'll want a good watering. They are not fast growers. I've grown several varieties, and love the plants. I just moved a dissectum last winter from a wind and sun exposed location about 50 feet where it's now near the house, where it's 3/4 protected from all wind, and gets only about 3 hours of sun a day. It is thriving--it's putting out seed pods and showing beatiful red tinges on the new leaves it didn't show in the other location (Shigare Bato). That plant will only get to about 7 feet tall. One possibility if it will grow in your climate is Shishigashira, which has a funky leaf and is considered very desirable & expensive. It grows slowly but will only get to about 12 or 14 feet, maybe growing 3-4 inches a year. A 4 footer will probably set U back $250 to $600. Another possibility is Seirya, a classic green upright Japanese Maple--not sure about top height. Again, important to check which Maples will grow & thrive in Zone 5.

I wonder whether your maple will make it through the winter in its current situation, Ryan. It sounds pretty sad. If it were my tree, I would go ahead and take a chance by transplanting it. It sounds as if you know what you're doing and would handle the job properly.

Hydrangeas are beautiful, but they don't do well where there are lots of deer.