Rhododendron kuisianum, the Kyushu azalea, is a low-growing Japanese species, only 18 inches high but is not hardy in Zone 5. Try Zone 7. R. linearifolium 'Macrosepalum', the plant is 3 feet tall and the leaves are deciduous and 3 inches long. But the flowers are even more curiously shaped than those of the species; they have 1 1/4-inch-long sepals that overshadow the petals. The flowers of this variety are fragrant and have been bred in several colors; in one, 'Polypetalum', flower petals and leaves are so similar in size that the plant seems to have pink and green leaves. R. poukhanense, the Korean azalea, is actually R. yedoense var. poukhanense. Although this plant is technically an evergreen azalea it is deciduous in cold climates. It is a low, spreading plant that is hardy to -15 F. Girard Hot Shot - Large flowers in a deep orange-red to scarlet. Plants develop an orange-red leaf color in the fall for winter color. Grows to 2' tall and hardy to -15F.

What do you mean by invasive? Spreading? or something that seeds all over out of the area? If you never ever want to have to pull something out or cut it back....you better be thinking annuals....but you will have to plant them every year....unless you get something that freely reseeds and then it could be considered invasive. If you are looking for a plant that is pretty, low growing and that you never ever have to do anything to....best be thinking plastic plants. I like lamium for a pretty low growing plant....I do have to pull some of it out when it spreads further than I would like....but it blooms white and pink and has nice varigated leaves and comes back every year so I don't have to replant. Linda C

If you keep african violets in a north window, they have to be close to the window. Pretty much directly on the windowsill. Another thing you can do is get a grow light. A single gro light tube is enough to supplement the natural light coming in from the window. I have one for my AVs, and they bloom pretty much constantly.

Those are all different kinds of hydrangea, and each have different winter hardiness. Rated in winter hardiness from best to worst they are (obviously) 2-3-1. Winters of 2014 and 15 were harsher than normal. #3 looks like a Nikko Blue which will bloom sporadically after a harsh winter. #2 is a Preziosa which takes harsh winters rather well. Those three all set flower buds on previous year's growth (a.k.a. Old wood). They can only withstand winter lows from about 0 (plant #1) to -20 (#2) Fahrenheit. Prolonged lows about -10 or below will take their toll on the stems, and in many cases, kill them back to the ground. So whatever the circumstance, do NOT do any trimming or pruning after about right now, each year, or you will risk cutting off next year's flowers. Otherwise, throw a large pile of leaves over #1 come November (to insulate it from winter conditions) and it will be much more likely to bloom. After about Memorial Day, you can cut back any brown or grey sticks that don't put out new growth. Until such time, the plants might look a little unsightly as their growth takes til almost early June to take off in zone 6.