I received this question from Walter, an old friend from my high school years:
“I’d like your opinion on the best flowers to put in my boxes on the porch this summer. I have flower boxes that I put on my porch rails that are about 3′ long and 5″ deep. They will get full morning sun for about 3 1/2 – 4 hours then total shade the remainder of the day.
I had impatiens in them last year and they did well for a while but began to fizzle out in July. I know they don’t like the sun a lo but I didn’t think that much would hurt them. Anyway I wondered if you had any ideas.”
I replied to Walter right away by e-mail, but I’ve just now had time to turn his great question into a blog post. So, here are my suggestions:
Off the top of my head, impatiens do seem like the best choice for planter boxes that get mostly shade. It was probably the intense summer heat that caused them to fizzle out last summer. Impatiens, petunias, and vinca tend to get long and leggy during the hottest part of the summer. I have found that, when they become leggy, cutting them back severely will encourage new growth, and helps them to bush out more. I haven’t had good luck with regular impatiens here in central Florida, probably because I have very little shade, but I’m creating shade as fast as I can. With my lack of shade, I have used SunPatiens (a brand name of sun-tolerant impatiens) and vinca instead, so I don’t have any photos of regular impatiens. Below are some photos of leggy vinca, showing how beautifully they recover from severe pruning of the “legginess”. The same effect can be obtained with impatiens.
Below is some vinca that I cut back a few months ago. It filled out quickly, and looks better than it did before:
Another Shade Lover – Waxed Begonias
These waxed begonias would be a beautiful option for your planter boxes. They can take morning sun, but need to be shaded from the afternoon sun. They are available in this darker pink, a lighter pink, white, and red. There is also some variety in the colors of their heart-shaped leaves.
Waxed begonias have either these dark-colored leaves or a lighter, true green. Both are complimentary to your garden.
One More Shade Lover – Caladiums
Another good choice for an area of mostly shade like you described is caladiums. There are some newer varieties of caladiums that can take more sun than the older varieties. Below are some photos of my caladiums that can tolerate partial sun are Red Flash, Gingerland, and Florida Sunrise.
These three caladium cultivars perform beautifully. You could combine them with impatiens for a little variety; and when your impatiens get leggy, the caladium leaves will act as a type of camouflage.
Caladiums in Winter
North of Zone 9, be sure to dig up your caladiums before the first freeze. Wash the bulbs to remove all soil. Lay them out to dry, then store them in a cool, dry, and dark place. A cardboard box or vented or net bag in your basement should be perfect. Replant them the following spring after all danger of freezing temperatures has passed.
A Substitute for Impatiens
Another option is vinca, which likes full sun, but does well in part shade, too — and it comes in lots of colors, just like impatiens. Here are some photos of vinca:
Walter, be sure to let me know how the flowers in your planter boxes do this summer. See you in the garden.