Tuesday, July 23, 2013

Perennials that Beat the Heat

Bob Henrickson

        Every year it’s the same thing, we know it’s coming, but it can’t be avoided. I’m talking about the dog days of summer, the summer doldrums, or simply July and August in Nebraska. The weather this time of year, with daytime highs in the 90’s, lows in the 70’s, test my patience as a gardener. The sultry, humid air forms a haze without any breeze, clinging to my skin. When there is a breeze it’s more like an oven fan turned on high, sucking the moisture out of my parched landscape. My garden needs some rain, but it’s not likely to come anytime soon.
        I have to admit that gardening through the summer doldrums usually made me cranky until I decided to do something about it. I was tired of babying my landscape plants and flowering perennials through the heat of the summer. Maybe it has something to do with my concern for conserving water, but I decided not to garden with plants that need my help all the time.  Instead I started using low-maintenance perennials that survive, even thrive, on their own and don’t wilt in the relentless summer sun. There are a plethora of perennial plants that have adapted to grow in harsh climates, under droughty conditions and thin soils. But it takes a special plant that dares to bloom this time of year, let alone grow and survive.
        I have always admired plants that seem to enjoy blooming in hot weather. Perennial favorites like the lavender-blue spikes of Russian sage, the dependable black-eyed susan, purple coneflower and ‘Autumn Joy’ sedum, have become mainstays in the border. We can also mention the ‘Moonbeam’ coreopsis, dazzling daylilies, garden phlox, yarrow, hosta and the striking hardy hibiscus. All of the previous plants are excellent choices for the hot summer perennial garden, providing beauty without much care. Thankfully, there are many more summer bloomers to choose from that are starting to gain the attention they deserve. The next time you think about planting consider some of the following plants to beat the summer heat.
        Patrinia (Patrinia scabiosifolia). The lush leaves of this plant look like those of the common Scabiosa plant forming a dense 2’ mound by early summer. The small bright yellow flowers are held in airy clusters high above the foliage in August to 4’ high. They may be cut and brought indoors, the fragrant flowers lasting a long time. They are excellent companions for almost anything and are great for hot, humid summers.
Wild quinine
         Wild Quinine (Parthenium integrifolium). This long-lived native perennial is also called American feverfew because its flowers resemble that of the common feverfew (Tanacetum parthenium). The large, flat-topped flower clusters, containing numerous small balls of snow white flowers, top the plants in summer. It grows in sand or clay and usually the stems fan out from a thick root to form a tidy clump about waist high. It has large, serrated leaves that are rough to the touch.
        Blackberry Lily (Belamcanda chinensis). The 2” showy orange flowers of this plant, each peppered with red spots are, unfortunately, very fleeting. The pear-shaped pods, however, are persistent and contain shining, black seeds for which the blackberry lily is named. The long sword-like leaves resemble that of Gladiolus. This 3-4’ plant is easy to grow in sun or part-shade. Another species, sold as ‘Hello Yellow’, has handsome gray-green leaves and unspotted, yellow flowers on 2’ plants.
        Wild Petunia (Ruellia humilis). This durable native has small petunia-like, lavender blue flowers that open in the morning and slide off by the heat of the day. Fortunately, the 1-2’ high plant gives rise to new flowers daily, extending the blooming season for weeks. These are short-lived perennials that can colonize an area by seed and for this reason combine well with short prairie grasses.
Blackberry lily
        Leadwort (Ceratostigma plumbaginoides). This attractive plant produces dense growth of glossy green foliage making it a fine groundcover for sunny areas or with afternoon shade. The intense, gentian blue flowers will start appearing in late July and last through the heat of August. In the fall the foliage can turn a bronzy red, contrasting nicely with the flowers.  Leaves emerge late in the spring.
        Scarlet Globemallow (Sphaeralcea coccinea).This western Nebraska native covers itself with small coral red flowers from early to midsummer on ankle-high plants. The attractive leaves are covered with fine hairs, giving them a soft gray-green appearance. This sun and heat loving plant makes a fine groundcover for naturalizing among short prairie grasses like blue grama or little bluestem.
        Compass Plant (Silphium laciniatum). The rigid sandpapery leaves align themselves in a North-South direction to escape the direct rays of the midday sun. The large leaves can be up to 15” in length and are deeply cut like a giant pin oak leaf. The plant flowers in August with dozens of large yellow sunflower-like flowers along a 5-7’ rough, tough stem. It benefits from full sun, poor soil and being ignored. Too much TLC results in lanky weak plants. Bold and impressive!
        Dotted Gayfeather (Liatris punctata). The dotted gayfeather is the most drought tolerant of the gayfeathers, with roots extending deep in the soil. It has microscopic dots on the underside of the leaves. In late summer the stiff flowering spikes are covered with feathery clusters of purplish-pink flowers to 2’ high. Each plant has a corm that can live for decades and give rise to dozens of flower stalks each year. This is one tough plant that thrives in the summer heat.

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