I have a 30 x 4' garden bed across my front yard in Victoria. I'm building a low rock retaining wall to distinguish this bed from the city property and to deal with some grade issues. The new grade will raise the level of the garden by 3 to 7". I'm wondering if I will need to lift my plants? I have hostas, lady's mantle, ligularia, etc that shouldn't be too hard to lift, but I also have an established rose, heavenly bamboo, thalicturum, japanese anemone, etc.
If the fill will reach as far as the bed, move the perennials out of the way beforehand. The trees might also be adversely affected. If the one on the right is a red alder it may perhaps have a tolerance for sudden deposits of soil over its roots, as it grows on flood plains in the region - I don't know.
Thanks RonB. Sorry I wasn't clear. The fill is going inside the bed once it is rimmed with rocks. The tree is a horse chestnut which ultimately will have 2 to 5 inches of soil added, 3 feet surrounding its trunk, but the root flare will barely be covered. I'm not worried about the tree. I'm thinking of the effort it's going to take to raise the more established perennials and the risk of losing them.
I don't see anything in the bed that's too big to pop out and heel in for a day or two somewhere while the fill's being done; just get good rootballs with the larger plants. So...not particularily risky to do, and the proper way to do the job. You`ll have to lift the iris regardless, so as not to bury the exposed rhizome.
Do you think roses and heavenly bamboo could tolerate about 4 inches of soil on top of existing? I'm reluctant to dig these up.
Yes, I thought of creating a well. I guess it might become a challenge to keep the well clear after a while, but worth trying.
