Tag Archives: dahlias

Darling Diva Dahlias

Like chrysanthemums, many people associate dahlias with the fall but dahlias can bloom from the beginning of summer to frost. Dahlia flowers are available in a wide range of sizes, colors, and shapes. Each bloom can be 2 inches across to more than 10 inches, in all colors except blue. Plants can reach one to 6 feet tall. Some plants have beautiful dark foliage instead of green leaves. Although there are 40 plus species there are thousands of cultivars. In addition, there are numerous forms such as the single, peony, anemone, collerette, star or single orchid, double orchid, cactus, waterlily, ball, and pompom.

Planting Tubers or Seed

To grow dahlias, you can either purchase tubers or start them from seed. If you purchase a tuber that is a named variety you will know exactly what the plant will look like. Plus, if you purchase cultivars that have been trialed and proven to do well in this area, you will have a good chance of success.  Seed is cheaper than tubers but there is a lot of variability with plant vigor and flower color. Although the seed will grow and produce a plant with pretty flowers for the garden, the flowers may not be exhibition quality.

Tubers can be planted outside in the ground after the average last frost date (Mother’s Day in the Washington DC metro area). Tubers also can be started indoors in April in containers under fluorescent lights or by the window to initiate growth. Seed should be started indoors under lights because planting seed in cold soil may retard the germination rate. Starting seed outdoors in May will only delay the time to reach blooming stage.

Caring for Dahlias

“Put the tuber in a four-inch hole and cover so that it is just peeking through. This way you can see the growth. When it grows, add more soil,” advises John Spangenberg, member of the National Capital Dahlia Society and owner of Crazy 4 Dahlias. John is a long time dahlia enthusiast who also sells tubers from his website.

Growing a dahlia plant is similar to growing a tomato plant: full sun and plenty of water and food. A dahlia can grow in less than 6 hours of sun but would not produce as many flowers. After planting the tubers, insert stakes such as tomato cages or posts. In the beginning, dahlias will require plenty of water, generally one inch of water per week. Dahlias are heavy feeders and will need fertilizer throughout the summer. Slow release fertilizers also work well. Dahlias appreciate a leaf or straw mulch to keep the tubers cool and to prevent weeds.

Encouraging More Flowers

In the beginning of the growing season, John recommends topping the plants to encourage bushier, sturdier plants with more flowers. The center bud (not flower bud but central growth) should be pinched back. “When you see three to four sets (or pairs) of leaves, break the center top off,” explained John.

Later in the season when flower buds appear, disbud or cut off smaller, lateral flower buds to encourage the top bud to form a single, larger flower. When a dahlia flowers, there are three stems with three buds in a v-shape. When the outer two smaller buds are the size of peas they should be cut leaving the center flower bud.

“The more you cut your flowers, the more flowers you get,” said John. If you don’t cut a flower for a vase, make sure you at least deadhead them. Deadheading is cutting off and disposing flowers that are past their prime to encourage the plant to produce more flowers.

Throughout the season, make sure the plant is well staked as it grows, feed it, and make sure it gets enough water.

Saving Tubers in the Fall

Dahlias are native to Mexico. Here in Washington DC they are treated as tender perennials and may or may not come back the following year. In order to ensure that the plants can be grown again next year, most gardeners lift and store the tubers in October.

“In the fall when get the first frost, cut the plant a couple of inches above the ground and let sit for a week or dig them up,” explained John. “You want to have the eyes develop and swell to be able to see them well. It helps to see the eyes when dividing the tubers. You can divide in the spring or fall but it is easier to divide in the fall.”

Dahlia tubers are swollen roots. Each tuber has to have an “eye,” which is a growing point in order to grow. From that eye the stem will emerge. In May, a single tuber with an eye is planted for a single plant. In the fall, when the plant is lifted out of the ground, there will be more new tubers joined together in an area called the crown. The “eyes,” or viable growing points, are in the crown. This can be stored as is or divided to create more plants.

John uses vermiculite in a box to store his tubers but there are many methods to store tubers. He finds vermiculite works best because it absorbs and releases moisture. Tubers should be in the coolest place in the house where there is constant temperature such as a crawl space or basement or a closet next to the outer wall of the house.

Because they are native to Mexico, one would think that dahlias would be easy to grow here with our sunny, warm summers. In fact, dahlias are native to a mountainous region in Mexico with more wind, less humidity, and cooler temperatures. Thus dahlias grow very well in the Pacific Northwest but have some difficulty in the mid-Atlantic. They need quite a bit of water, yet as heavy feeders, the rain can leach the nutrients. Plus the humidity can encourage disease. “In this area, we have issues with slugs, earwigs, rabbits, groundhogs, and deer,” said John. “Plus we have noticed that Japanese beetles prefer white and yellow flowered dahlias.”

Selecting Dahlias for Washington DC Metro Area

To choose a dahlia that performs well here, look to the National Capital Dahlia Society for recommendations. A branch of the American Dahlia Society (ADS), the National Capital Dahlia Society is comprised of dahlia enthusiasts and breeders who meet on a regular basis. Every year they manage a trial garden at the Agricultural History Park in Derwood, MD. “The display garden is a trial garden to test new introduction from across the country to see how they do here. We look at bloom quality and plant vigor and report this to the American Dahlia Society,” said John. Later in October, the Society members will dig up the dahlias at the trial garden and demonstrate how to save the tubers (open to the public). They also sell tubers next year so if you are interested in growing dahlias that do well in the Washington DC metro area, contact them via their website: http://www.nationalcapitaldahlia.org.

This past weekend, the National Capital Dahlia Society held their annual dahlia show at Brookside Gardens where flowers were judged using the ADS criteria. The photos in this article are dahlias from the Court of Honor, those dahlias that have been selected from all entries for final judging. The video is a scan of the Court of Honor.

Containers with Summer Blooming Bulbs: Living Flower Arrangements

Earlier this month, I had the opportunity to create a container with summer blooming bulbs, a “living flower arrangement.” I along with a group of garden writers and communicators visited Brent and Becky’s Bulbs in Gloucester, Virginia. I have known Brent and Becky for years but have never made the 3-hour drive to the Tidewater area. Brent and Becky’s Bulbs is THE place to buy bulbs in the mid-Atlantic area. Although known for daffodils, they sell spring and summer blooming bulbs as well as some perennials and grasses.

Becky provided a “living flower arrangement” workshop for the group. Living flower arrangements are spring or summer blooming bulbs that have been planted in layers in a large container. As they break dormancy and flower, they provide an array of different blooms, similar to cut flowers in a vase. Usually the containers are outside, making them ideal for porches, patios, decks, and front doorways.

Becky began the workshop by giving us each a large vinyl container with drainage holes. After adding about 4-5 inches of potting soil, we planted three lilies, Lilium orientale ‘Mona Lisa’. These are the fragrant, oriental lilies with the large star-shaped flowers. This particular cultivar was bred to be short, only 1 to 2 feet tall, with rose/pink flowers.

While she distributed the bulbs to us, she explained the plants and the planting depth. The lilies produce stem roots that act as anchors so the plants stand taller if they are planted deep, about 6-8 inches, which is why they were planted first. Becky also gave each of us a special ruler indicating how deep different bulbs should be planted.

After covering the lilies with soil, we planted one Dahlia ‘Gallery Leonardo’ and one Zantedeschia ‘Paco’ on the same level, across from each other. The Dahlia Gallery series is more compact and floriferous than other dahlias, making them ideal for containers. The dahlias grow to about 1 to 2 feet tall and the flowers have pointed petals, in apricot, peach, and salmon colors.

The Zantedeschia, also called calla lily, has a flower that looks like the peace lily houseplant. The spathe is a dark rose color and the plant grows to about 1 to 1 ½ feet tall. They look exotic but they grow well outside in this area. The bulb looked like a biscuit, it was hard to tell which end was up. Becky explained that if you cannot figure out the top and the bottom, plant the bulb sideways and it will sort itself out.

After covering with soil, we planted 10 Oxalis regnellii var. triangularis. Also known as the shamrock plant, this particular variety has burgundy-colored, triangular-shaped leaves and small pink flowers. Shamrocks grow to about 6 inches tall and prefer shade which they will get since they will be under the foliage of the other plants. These “pips” were about the size of a thumb, so it was easy to fit 10 across the container.

After covering with soil we dug a little hole in the middle and added one pink muhly grass (Muhlenbergia capillaris). This was a small plug, about 2 inches wide, which will eventually grow several feet tall. Muhly grass is an ornamental grass with blue green foliage. In the fall, the pink variety blooms, creating a beautiful pink haze in the landscape. Becky added this because she felt participants should go home with something pretty to see on top. I agree, it was the promise of great things to come.

Becky also distributed a handout with care instructions and possible combinations of the three-layered technique. We had a great time creating the living flower arrangement – it was definitely a hands on experience!

As I drove home with my container in the back seat, it occurred to me that this technique could be used many ways. Dormant bulbs can sit in a container for a while and not die.  If I take the muhly grass out (which needs water and light), I could “package” the container with tissue paper and give it as a gift. These containers could be “instant” gardens, just water and watch! And for those who may have trouble gardening, these could be great gifts –pre-made flower gardens.

When I got home I took the grass out and put it into another container. I then wrapped the large container with tissue paper I had in the house just to see how it would look. I could see the potential – giving a container with several types of bulbs could inspire others to garden or help those who have limited physical capabilities still enjoy growing flowers.

As I write this at the end of April, I have put the container outside on the deck where the temperatures are now warm enough. Already the bulbs are sending up shoots. I will post photos when they flower, but the plant links in this article to Brent and Becky’s catalog should give you an idea of the flower and additional information. Try this method of three layers of summer blooming bulbs for a beautiful container. I know I will spend the summer enjoying my living flower arrangement and the memories of a great weekend at Brent and Becky’s Bulbs.

Brent and Becky’s Bulbs is a family-owned, mail order business in operation since 1900. They have a fall planted/spring flowering catalog and a summer-flowering catalog. They have a Bulb Shoppe full of bulbs and gardening accessories surrounded by the Chesapeake Bay friendly 8-acre teaching garden. The public is welcomed to visit the Shoppe and gardens Monday through Saturday, February through mid-December. Workshop and gardening programs also are offered onsite and Brent gives lectures across the country.