When Mother’s Day rolls around every year my deep rose azaleas named for the event, ‘Mother’s Day’, bloom and the color is picked up by the soft delicate centers of perennial cornflower, also known as Mountain bluet and perennial bachelor’s button. This color echo is one of my favorites and often does not last very long but perhaps that is why I treasure it so much. Mountain bluet is a beautiful plant with uniquely shaped blue flowers and blue-gray flowers, and it is an asset in any garden whether it has an echo or not. I would not voluntarily be without it but I must confess that this is not a plant that loves my garden, perhaps because I have only grown it in gardens that are hot and humid in summer where they languish. Allen Armitage notes in his book Herbaceous Perennial Plants that in his Montreal garden the plant is a weed but that it lacks vigor in the South. It’s also a good cut flower.
Type: Herbaceous perennial.
Bloom: Two-2 ½” deep blue thistle-like flowers with rose center in late spring to early summer. Sparse rebloom in late summer-early all may occur. Shingle-like bracts around the flowers are edged with black.
Size: 1 ½-2’ H x 1-2’ W.
Light: Full sun-part shade but may become lanky in too much shade.
Soil: Average, dry to medium, well drained soil; does not like wet feet.
Hardiness: Zones 3-8.
Care: Remove spent flowers stems to ground level; may be pruned back hard in mid summer to encourage compact habit; divide plants every 2-3 years where vigorous.
Pests and Diseases: None of importance but susceptible to aphids, leaf hoppers, rust, aster yellows and stem rot.
Propagation: Reseeds; spreads by stolons; division.
Companion plants: Catmints (Nepeta spp.), pink azaleas, lupines, hardy geraniums lady’s mantle, Shasta daisy.
- ‘Rosea’ (pink)
‘Gold Boullion’ (blue flowers with chartreuse foliage)
For more information on Mountain Bluet and other perennials you might like to read Allan Armitage’s fabulous book that gives all kinds of information on a vast number of perennials in an interesting and witty conversational style. I take it with me to garden centers and consult it before buying any plant I have not grown before. Especially valuable for propagating plants vegetatively or from seed and on the probable success of growing plants in different parts of the country.
Buy “Herbaceous Perennial Plants: A Treatise on Their Identification, Culture, and Garden Attributes” from Amazon.com.