Easy Care Perennials for Late Summer

As summer winds down in late August and early September, the perennial border can look a bit sparse, a bit dry and a bit tired, but there are several sturdy perennials which can bridge the gap and add color to the border between the blooms of the daylilies and asters. 

The following featured perennials are all drought-tolerant, full-sun plants that have the flowers of a supporting cast member rather than being sassy showgirls, although Helen’s Flower could qualify as a showgirl depending on your point of view.  The flowers of this plant are small, about an inch across,  but there are many and this plant stands a good four to five feet tall.   Helenium autumnale is a vigorous clump-forming perennial.  It does best in full sun and seemed to barely wink at  the dry conditions of this August.  It starts to bloom in late August and continues through the bulk of September. There are several cultivars to choose from at the garden center and their color ranges from deep mahogony through yellow.  This plant is native to Eastern and north central North America and the butterflies and bees love it.   

Leadwort or blue plumbago, Ceratostigma plumbaginoides, is a low-growing, spreading groundcover which tolerates dry conditions.  Its blooms are electric blue highlighted by a reddish tinge of the stems.  This plant could be used in a curb garden, in the front of the perennial border, or as a groundcover.  Blue plumbago actually thrives in well-drained soil in full sun and its late blooming attribute only adds to its charm.  Blue plumbago hails from China and is quite a hardy plant, growing well in Zones 5-9.  I find that it does spread to a larger clump fairly quickly.  I have underplanted it with spring-blooming Scilla siberica, which works well as the plumbago is late to emerge and leaf out.  When the blue plumbago finally does send out leaves, the scilla is past bloom.

Calamint is a plant growing in popularity due to its low-maintenance attributes.  It has small, glossy green leaves with upright stems and a stalk of tiny white to pale pink/lilac flowers.  It hails from Southern Europe and has a minty fragrance when the leaves are bruised.  It makes a great edging along a walkway in addition to blending into the border, where it remains shy until it is covered in flowers in late summer. 

Hardy geraniums, or the cranesbills, are indispensible to the perennial border and there are over 400 species of hardy geraniums.  There is a geranium for just about every different garden location and soil type, but one that has been developed and is used almost to the point of overuse is Geranium ‘Rozanne’.  Can a plant which blooms for three or four months be overused?  Probably, but this geranium is a welcome addition to any border.  I find that in richer soil, Rozanne gets a bit gangly but with pinching and clipping, it produces a wonderful pinky purple flower all summer long.  It can be a bit of a weaver with its blooms appearing above or entwined in other border flowers.  That just makes it a great cottage garden plant.  In average soil it remains quite well behaved, forming a good-sized clump with respectable flowers. ‘Rozanne’  I include it because it received no special treatment this dry season and it is still loaded with blooms.   Do you have any sturdy perennials to add to this list?  Please feel free to share.