We’ve been in the same home since 1984. When we bought the house it was on a heavily wooded lot, and over the years I’ve filled it up with shade-loving shrubs and perennials, some of which are actually still alive. Hostas that I remember planting the first year we were here are thriving, although sooner or later this summer they will get hit by the deer. Hellebores that I got as seedlings from Mr. Behnke’s garden in Burtonsville, probably in 1985, are still happy, at least as far as I can tell since they are reticent to express their feelings.
But things are changing. Because of water-in-the-basement issues we had excavations performed around the foundation of the house in the back yard to repair cracks; improved drainage away from the house; and replaced a deck with a patio. As part of this project we had to remove an oak that was too close to the house. Meanwhile, in the front yard a massive oak has entered retirement, helped along by two factors: excavations for new sewer lines (more water in the basement, full of organic material) on one side of the tree, and…the results of the high rainfall of the last year, soil saturated with water on the other side of the tree which is the lowest part of the front yard.
When soil stays saturated with water, oxygen is excluded, and roots die. This tree is not dead but its canopy has thinned and at some point the tree will probably have to be removed. So, more sunlight reaches the ground around the house, especially between the high intensity hours of say, 11AM to 3PM. Good news and bad news.
Good: I can finally grow herbs. Basil, rosemary, and lavender are thriving in clay pots on the patio. They aren’t as flavorful as they would be in full sun all day, but they are full and attractive. Also, some established plants in the ground that are somewhat shade tolerant are happier now that they are getting more sun: daylilies in particular are blooming much more vigorously this year.
Bad: sunburn on the shade lovers. On some, it’s just a change to lighter green foliage so far; e.g., wild ginger, rodgersia. If that’s all that happens, it’s not a big deal. On the hostas though, it’s variable. I recall reading that green- or golden-leaved hostas are more tolerant of sun than the blue. That is sure the case in my garden. The golden ones are much more golden and attractive: in the past they faded to a greenish yellow. The green ones are…green. The blue ones look bad. The leaves have faded to a yellowish blue, often with scorched patches, which then die. I’ll have to do some digging and moving. (I don’t have any white-variegated hostas in the sunny area; my recollection is that the white portion of the leaf is prone to burn, though.) I’ll stick with my general recommendations for shade plants.
Almost all will be more vigorous and flower better if they have a couple of hours of morning sun. Sun from noon into the afternoon will be too intense for many of them and they will burn. Some plants (e.g., hellebores) may wilt even if the ground is moist. Blue hostas seem to be the most subject to burning.
These photos include two sets of before and after photos of blue hostas, in shade and with sunburn. Note the fading, scorched and dead areas.
Larry Hurley, Retired Behnke’s Horticulturist