My south neighbour complains of dampness caused inside his house due to my adjacent 23 inch high by 2 foot wide by 34 foot long, planter and plants. This whole unit and plants must be moved from south side of the small back yard to the north side of the yard. From July to September when is the optimal time for the transplanting? Thank you.
It is far better to transplant perennials and shrubs when the weather cools off, so September would be the optimal time. Transplanting in hot weather can be quite stressful for plants. However, if it makes sense for other reasons to move your planter sooner rather than later, transplanting in the summer months can be done with care, and with the proviso that some of your plants may experience what is known as transplant shock. Whether you are moving shrubs or perennials, the principles are similar, but there are additional steps you can take with established trees and shrubs to help transplant them successfully. This website provides some valuable details on root pruning and protection for trees and shrubs: https://www.clemson.edu/extension/hgic/plants/pdf/hgic1055.pdf. Whether you move your planter in the summer or early fall, the steps below remain the same.
Choose a cool and overcast day, and work as quickly as you can. Water your plants thoroughly the day before you plan to move them. When you dig your plants up, try to disturb their roots as little as possible, and bring as much of the root as you can with the plant. Once plants are dug up, they should be moved as quickly as possible. If you need to leave your plants while you move their planter, make sure their root balls and surrounding soil are well wrapped in damp newspaper or burlap and they are placed in a cool, shady location. When you are replanting, make sure your hole is big enough and put a good handful of organic material such as compost in the bottom. Put the plant into the hole and fill it approximately halfway with water, permitting the water to run out. This settles the soil surrounding the roots. Fill the hole with soil, and press down gently around the plant to ensure there are no pockets of air in the soil. Once all your plants are in their new location, it is a good idea to add a top dressing of organic material. Water thoroughly, and make sure you continue a program of watering daily for the next few weeks to help your plants establish themselves. If your new location is in full sun, providing some additional shade for your planter, perhaps with a garden umbrella, will also help to lessen the transplant shock for your plants. If your perennials do not seem to be responding well to their move, you should consider trimming them back by as much as one-third, which will allow them to put more of their energy into root growth.
Very best of luck with your planter move.