What is the opinion about planting 1 gallon maples into the ground? I speculate that it might have a harder time at first but eventually the roots need to meet the native clay soil no matter what size container it came from. It will receive proper watering. The problem with the clay soil is no matter what I add to improve the texture or drainage it will return to the original state sooner or later. Keeping the clay somewhat moist seems to be best thing to keep the soil soft.. It seems to me maples that are in the ground just grow faster and better anyway. I have planted one of my 1 gallon plants in the ground already (after a few weeks in the pot adjusting to the sun here) Please let me know how to best care for it to help it get established.
To resolve the problem of the coarse potting soil being a different texture than the fine clay remove the potting soil when planting. I use a pail or tub of water to do this, thus keeping the plant moist the whole time. Amending of small planting holes merely enlarges the area of different texture the plant has to overcome. Textural differences are a problem because they affect how water moves through the soil in the vicinity of the plant. Amended planting holes dug in heavy soils may receive water from unmodified soil around hole during wet periods, as well as shed it to the same soil during dry ones. This latter problem is why potted stock planted at this time of the year can be difficult to keep moist. Some soils are already becoming rather dry.