This is the best year ever for my upright sedum (Hylotelephium) containers on the rooftop. All the superlatives fit my sedums this year: the tallest, most robust, most colorful, most floriferous, and most pollinators attracted. After years of growing them on a Chicago rooftop, I think I have discovered the right formula.
The first step is proper exposure. I always give them full exposure, but most times the sedum pots were totally isolated. This year I placed them among other large containers, so they did not bear the full brunt of the stunting, drying wind. This also contributed aesthetically. The sedum pots were part of a “perennial border look” with lilies, geraniums, and other plants completing the scene.
Secondly, the pots were well watered for the first time. Just because a plant is drought tolerant doesn’t mean that drought is the best condition for it. Sedum ‘Autumn Joy’ is not like agave, cactus, or other true desert plants. Regular watering won’t rot them. In fact it helps them grow large and lush. (The regular watering for the sedum ‘Autumn Joy’ was a consequence of the effort to keep the basket-of-gold plants healthy. Basket-of-gold (Aurinia saxatile) and sedum ‘Autumn Joy’ are perfect container companions. Because of the exposed conditions and lack of watering, the basket-of-gold would show visible signs of suffering by late summer. Regular watering kept the basket-of-gold lush and helped the sedum ‘Autumn Joy’ too.)
Finally, the aphids did not get outta hand. For the past two years they have covered the sedum ‘Autumn Joy’ all fall and reduced the size and duration of blooms. Ladybugs and Safer Insecticidal Soap helped keep them in check through the season; and now there aren’t many if any. A couple of falls ago I noticed black aphids on the sedum. I didn’t address it, because it was already cold and I figured they would die out. Wrong! They lived and fed on the sedum deep into fall. Next spring they were back before the plants had grown 4”. They were so bad in 2009 that the plants were stunted and once again the blooming was curtailed. This year I started early with the insecticidal soap and added ladybugs when the aphid numbers started to go up. We had ladybugs and their alligator look alike babies everywhere. Safer proved itself this year. Despite spot spraying for infestations, ladybugs, butterflies, and bees where able to thrive. I would spray a plant for aphids and in less than a day I would see ladybug larvae or skippers on the same plant. That doesn’t happen with residual pesticides.
I’ve found the formula for great rooftop container sedum. Some shelter or at least shared exposure, regular watering, and ecologically approved pest control. Unfortunately, their big fluffy blooms are a little bittersweet, because this begins the end of the season. Actually I start to get wistful when the lilies bloom. They mark the mid season; and even though lilies are my favorite, they always seem to arrive too soon. Now with the sedums at their peak the only perennials left to flower are the asters and autumn crocuses. So while I’m enjoying the show, I’m also lamenting (maybe honoring is a better word) the close of a great gardening season.
Get Out & Grow
sedum container shared exposure
