If plants were like movies, balloon flower (Platycodon grandiflorus) would be one of those critical successes that nobody goes to see until word of mouth gives it a boost. Balloon flower, also known as Chinese bellflower, has been racking up great reviews for more than 50 years, yet it's still not found in many gardens. Perhaps some good words here will increase its popularity.
My obsession with balloon flower started 10 years ago, when I ran across an endorsement in Wyman's Garden Encyclopedia (1977 edition). Author Donald Wyman calls it "one of the best garden flowers for the perennial border." I kept reading. In A Southern Garden (1942), Elizabeth Lawrence wrote: "Once entrenched, [balloon flower] improves with time and should be one of the most permanent plants in the border. It is certainly one of the most beautiful."
Permanence. Beauty. And it's blue. I collected some seeds and started growing balloon flowers: tall ones, dwarf ones, and in-between-sized ones. Now let me add my own review to the others. They are as easy to grow as daylilies, and they're probably the most reliable blue bloomers you'll ever grow. As an added benefit, flowering peaks in mid- to late summer, after many other perennials have already come and gone.
This stalwart member of the campanula family is native to China. Its dominant flower color is a dazzling blue, with white and pink forms to complete the palette. Dependably perennial in USDA Hardiness Zones 3 through 8, balloon flower tolerates both extreme cold and scorching summer heat. It thrives in full sun but also adapts well to partial shade, especially in zones 7 and 8.
The plant's common name makes perfect sense. The flower buds are hollow balloons, which gradually inflate and color up. Finally the buds burst open into star-shaped flowers 2- to 3-inches across. One variety, 'Komachi', never pops open, which I find somewhat deflating. I'll take stars any day.
Varieties differ in flower color and plant size. The Fuji series, the most widely sold, is also the tallest, producing blue, pink, or white blooms on 30-inch-long stems. Because of its height, Fuji always benefits from support, as do 24-inch-tall 'Double Blue', 'Pink Pearl', and 'Shell Pink'. Because plants grow from numerous basal stems that rise directly from the roots, heavy-gauge grow-through supports or support rings are ideal. I use a circular tomato cage shortened so that it stands about 15 inches high when securely installed, but any staking method that provides knee-high loose support is fine.
More compact varieties, less than 18 inches tall, form graceful mounds with little or no staking. Blue 'Mariesii' and violet-blue 'Apoyama', or white 'Pumilum Album' and 'Apoyama Fairy Snow' fit into this intermediate category, and 'Sentimental Blue', a 6-inch-tall dwarf, is ideal for use in containers or small beds.
Balloon flower will prosper whether you begin with seeds or plants. Seeds are easy to start, but because plants do not flower well until the second year, you may want to save time by buying container-grown plants.
To start seeds, barely press them into moist seed starting mix, enclose the containers loosely in a plastic bag, and keep them at 60oF and in moderate light. Seedlings should appear in about two weeks and can be shifted to larger containers a few weeks later. In my zone 7 garden, I keep seedlings outdoors in pots through their first winter, then set them out in the garden when they are a year old. Plants need at least 6 weeks at or below 40°F to flower, but flower best with at least 12 weeks at these temperatures.
Balloon flowers develop heavy gnarled storage roots, so it's easy to move plants if needed. And, should you want to propagate them, simply take a heel cutting in late spring, when the new stems are about 2 to 4 inches long. Gently dig down to where the stem joins the roots, and use a sharp knife to nick off a stem with a 1/2-inch chunk of root. Pot the cutting, keep it constantly moist, and it should quickly take off. I get close to 100 percent success with this method, compared to only about 50 percent survival of tip cuttings dipped in rooting hormone and set to root in a sandy potting medium.
To get the most prolific bloom, situate plants in a well-drained site and fertilize them to support strong growth. In my very average clay, I scratch a controlled-release fertilizer into the soil around the plants in spring; in summer I apply a 2-inch-deep organic mulch. In fall after trimming off the dead stems, I add a little more mulch and then put the wire support ring back in place. Plants are a little late to show themselves in spring, so marking their location keeps me from accidentally digging too close to them later on.
Light deadheading helps to extend the bloom time, and in some years the plants inexplicably produce a second flush of flowers in early fall. If you cut flowers to use in bouquets, sear the stem ends the moment you sever them from the mother plant. Otherwise their vase life may be limited to one day.
Balloon flowers make great neighbors to other plants because they don't spread and only need dividing about once a decade. In sun, I like to flank them with yellow plume celosia or orange Cosmos sulphureus. In large decorative pots, pair dwarf 'Sentimental Blue' with red verbenas. In partial shade, use balloon flowers as accent plants placed among foxgloves, hostas, or lamb's ears.
Allan Armitage, perennials expert at the University of Georgia, suggests teaming plants with tall yarrows such as 'Coronation Gold'. He also notes that balloon flower is one of the lowest maintenance and most rewarding of perennials. Plant reviews don't get much better than that. I give it four stars.
Barbara Pleasant is a long-time contributor to National Gardening. Her colorful gardens in Brevard, North Carolina inspire her writing.
Photo by Suzanne DeJohn/National Gardening Association