Armstrong is a cultivar of the Acer rumbrum or red maple family of trees. It is prized for its upright and compact canopy that blooms red in the spring, develops red fruit in the spring and summer, and has fall foliage color in hues or orange, red and gold. It reaches up to 60 feet in height at maturity with a comparatively narrow spread at a maximum of 25 feet. It is more heat and drought tolerant than other maples and is therefore more widely planted in the warmer southern climes.
Select a planting location. It should be able to accommodate the size of the tree at maturity and have full sun exposure or a partial daily shade exposure. If you're planting more than one tree, they should be at intervals of at least 12 feet unless you intend to have the canopies intermingle for a raised hedge effect or will be pruning the canopy for size.
Conduct a soil test. If you aren't sure about your soil's pH, you may need to amend the soil. Test kits are available at most home and garden centers, or your local cooperative extension can help as well. Armstrong will grow in acidic to neutral soil, but heavily alkaline soil may need to be amended with iron sulfate to prevent or treat iron chlorosis. Provide a planting soil that is nutrient rich and moist as Armstrong will tolerate even periodically flooded soil provided there is some movement of water through the soil.
Dig a planting hole twice the diameter of the nursery container or balled and burlapped root mass and at least as deep. Scrape the side and bottom of the hold with your shovel to loosen the soil for new roots to easily penetrate. Add a few pounds of compost into the hole and into the back fill soil to act as a gentle fertilizer.
Slide the tree from its container or burlap wrap and set into the prepared hole. Make the top of the root ball level or just proud of the surrounding soil. Turn the tree so that its best aspect is facing the direction from which it will most be viewed. Make sure the trunk is straight and the canopy somewhat level.
Back fill the soil and compost around the root ball tamping down with your hands or foot periodically to just lightly compact the soil and secure the tree in place. Create a watering moat with the remaining excavated soil and compost around the drip line of the tree.
Fill the moat with water allowing it to percolate down into the soil before filling a second time. Keep the soil very moist for the first six weeks so the roots are supported and not stressed by drought while settling into the new soil.