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INTRODUCTION

Cone crazy?  Our guest writer this week, William Cullina, explains the coneflower species, Echinacea.  Learn, in non-technical language, how the coneflower grows, why some flourish in wet to normal soil, and some are difficult to grow or to transplant.

The natives with slender leaves also have a taproot and are suited to dry areas.  They can be difficult to transplant.  Many hybrids that share the narrow leaf fall into this category.  They do not want fertile or moist soil.  These coneflowers need to be transplanted when young into a difficult, sunny, dry space.

Look for hybrids with wide leaves in beautiful new colors of red, white, yellow, and orange along with the signature pink and purple.  The wide leaves denote a strong purple coneflower parentage in their background.  The plants will be easier to transplant (no taproot) and will stand up to most garden conditions if they share this background.

Bill writes that raising coneflowers from seed is very easy, and he tells how.  He also suggests that if you have a Tennessee yellow coneflower in your garden along with purple coneflower, you might find your own hybrids coming up from seed. 

Find out how to grow coneflowers successfully, especially the purple coneflower and its hybrids, which have evolved into true garden plants.  GardenSMART visited the Coastal Maine Botanical Gardens and visited with Bill Cullina, the Plant and Garden Curator.

---Anne K Moore August 20, 2009---

http://www.williamcullina.com/files/IMG_576.jpgCHOOSING & GROWING ECHINACEA PURPLE CONEFLOWER

William Cullina, Plant and Garden Curator, Coastal Maine Botanical Gardens

NATIVE WILDFLOWERS-HOW THEY GROW

There are very few native plants with wider appeal than the coneflower (Echinacea spp.)  This uniquely North American genus of ten species epitomizes the meadow or prairie wildflower.  In general, coneflowers are easy to grow in sunny, well-drained soil and the large daisy-shaped blooms remain colorful for at least a month.

The plants grow from a woody crown, sending up first a tuft of basal leaves followed by leafy flower stems that rise up in mid-summer.  Each stem is topped by one large bloom that can be as much as 4 inches across and once the first bloom begins to fade others grow from small side branches to take its place.

Like other members of the aster family, Echinacea flowers are technically inflorescences made up of many small flowers serving one of two functions.  Each petal or ray is really a single flower with five petals fused into one.  The ray flowers form a ring around the central cone, which is also composed of many individual flowers that have no petals.

The division of labor has particular consequences for pollination and seed set.  The rays are sterile, functioning merely as advertisement for the less noticeable fertile flowers that make up the cone.  These later produce nectar and pollen as well as seeds.  A bee or butterfly cannot help but notice the ring of large, colorful ray flowers as it passes, and the cone provides a perfect landing pad for the insect as it comes in to investigate. 

What the bug finds is a host of little, nectar rich blooms packed in together a sort of one stop shopping that is very appealing.  Rather than wasting energy flitting here and there, the bee or butterfly can settle in and drink from a bunch of flowers at once.  When you plant coneflowers, the butterflies and bees are sure to follow.

This combination of colorful advertising and concentrated, easily accessible flowers has made the aster family one of the most successful and diverse in the world.  However, the coneflowers appear to be a new member of this large family as most of the species are nearly similar in leaf and flower shape and color.

Coneflowers likely evolved fairly recently during the drying of the North American climate during the Pleistocene that allowed the development of prairie grassland habitat from the Southeastern U.S. to the western mountains.  The typical color of the bloom is light lavender with a deep red or black cone bristling with yellow or red knobs.  These knobs or bristles likely aid pollination by providing scaffolding for the pollinator to crawl on and then discourage predation of seeds by birds.

There are two basic leaf types in the genus - one characterized by a 2-3 inch wide, ovate blade with a rounded or heart-shaped base and the other by a narrow (<1 inch wide) linear leaf.  The narrow-leaved species tend to grow in drier habitats than the two wide-leaved ones (Echinacea purpurea - purple coneflower, which is found in the prairies west of the Appalachians and Echinacea laevigata, smooth purple coneflower, which is a rare species from the eastern side of those same mountains).

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The most widespread of the narrow-leaved species is E. pallida, pale coneflower from the prairies east of the Rocky Mountains.  It is closely related to the smaller E. angustifolia, narrow-leaved purple coneflower, which grows on both sides of the Rockies.  There are several other related species, notably Tennessee coneflower (E. tennesseensis), which is very similar to E. angustifolia but restricted to dry, rocky prairie remnants on the
Cumberland Plateau of Tennessee.  Like most coneflowers, it is adapted to rather parched, fire-prone grasslands.  

From a horticultural point of view, this is important as most of the species resent wet soils and poor air circulation around the leaves and crown of the plant.  They have large, fleshy taproots that burrow deep in search of moisture and act as a food pantry to help the plant recover after drought or the frequent fires that sweep through their habitat.

CULTURE

Taproots resent disturbance, rot easily if drainage is poor, and generally make plants more difficult to transplant and cultivate.  The exception in this genus is Echinacea purpurea, which prefers damp or even wet http://www.williamcullina.com/files/IMG_589.jpgprairies and consequently has evolved a more forgiving fibrous root system that functions much better in this type of soil.

From a functional point of view, purple coneflower is a much easier and forgiving plant to cultivate and it is no wonder that it has become the unquestionable favorite among gardeners.  It has a further advantage in that its ray petals are wide and flat unlike the narrow or curled rays of the other species.

The rays of wild plants point downward much like the feathers of a badminton shuttlecock, though breeders have selected forms that hold their rays parallel to the ground for flatter appearance.  Tennessee coneflower is the only species with rays that naturally orient lightly upwards, and breeders have crossed this one with purple coneflower to yield hybrids with even flatter heads.

THE HYBRIDS

One coneflower stands apart from the others in a more noticeable way.  The http://www.williamcullina.com/files/IMG_583.jpgvariety of Echinacea paradoxa from Arkansas and Missouri has yellow ray petals.  Like a red-haired child among a family of brunettes, yellow purple coneflower is a bit of a mystery.  As a garden plant, it is interesting but not outstanding as there are plethoras of yellow daisies available that grow more easily and have larger, flatter flowers.

However, several breeders realized that if you cross this plant with purple coneflower, all manner of white, orange, red, purple, and pink progeny result.  Some crosses also bring in Tennessee coneflower to flatten out the rays.

In recent years, a number of yellow, orange, and red coneflower hybrids have hit the perennial market and most are quite beautiful.  However, many have suffered from the same problems that the tap rooted species face under cultivation - namely root rot and transplanting difficulty.  The best hybrids have a double dose of the fibrous-rooted purple coneflower in their background and you can distinguish these by their wider leaves.

Color is not the only option as regards coneflowers.  When I worked at Niche Gardens in the early 1990's, we selected and introduced a compact coneflower I named Kim's Knee-high after the owner of the nursery, Kim Hawks.  It grows to only 16-18 inches, a half to two-thirds the height of a typical purple coneflower, yet it flowers prolifically.

This was one of the first coneflower cultivars to be tissue cultured and it has proven itself in gardens over the last 15 years.  Tissue culture and the natural variability of the plants have both yielded other forms including types where some or all of the cone or disk flowers develop double or semi-double ray petals.  As Itsaul Plants, one of the primary coneflower breeders operating today puts it, we have "gone cone crazy!"

HOW TO RAISE CONEFLOWERS FROM SEED

Though some of the hybrids are sterile, you can raise the species easily from seed, and if you grow yellow purple coneflower together with the purples, you might even find some hybrids among its seedlings.  The seed is ripe when the cone dries out.  At this time, the bristles turn dark brown and rather sharp and spiny.

The silvery gray seeds are packed in among the bristles and both fall out when you shatter the cone.  I don't bother separating the seed from the bristles.  The seed germinates after 6-12 weeks of cold, moist temperatures.  

Sow seeds outdoors or in pots in late fall (cover them lightly).  Alternatively, you can soak the seeds in a cup of water for a few hours, and then towel them lightly dry before putting them in a sealed baggie in the refrigerator for the requisite number of weeks.  After their chilling, sow the seeds indoors or outside after the danger of frost is passed.  They should sprout in 2 weeks.

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In the nursery, coneflowers mature rapidly and often flower the first summer from seed germination in the spring.  Transplant your plants into well-drained but moist topsoil where they will receive at least 5 hours of summer sun.

HOW TO GROW

Many coneflower species are restricted to high pH soils, so add lime if your soil is naturally acidic (below a pH of 6.0).  The narrow-leaved species do better in slightly nutrient-poor soils, but purple coneflower and its hybrids need higher fertility to do their best.  I have found that most of the hybrids and fancy cultivars are less vigorous than the wild type purple coneflower, so you will need to give them more attention.  Unlike their wild cousins that grow just as well in the meadow or prairie, the fancy cultivars are really strictly garden plants.

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