How to Cut Dahlias for a Vase or Bouquet

The perfect flower for a vase is one that blooms the more you cut them. That’s just what dahlias do. The range of dahlia colors (including the famous black dahlia) is astounding, with two-tone or ombre colors that will blow your mind. It’s no wonder these beauties have made a big comeback in recent years and are more than ever popular for growing in a cut flower garden. This guide will take you through everything you need to know about when and how to cut dahlia flowers for a vase or bouquet arrangement. 

How to Cut Dahlias for a Vase or Bouquet

Key Takeaways

Dahlias can be cut in summer, trimmed just as the blooms start to open. Cutting in the right spot along the stem will encourage repeat flowering. Use a hot water treatment after cutting to preserve the vase life of the flowers, or dry them for an even longer-lasting bouquet. 

Dahlia Flowering Season

A collection of colorful dahlia flowers in bloom

Dahlias are planted at the end of spring. In the right conditions, they will flower eight weeks later, from summer into autumn. In a nutshell, they should be planted in a position that has at least 6-8 hours of sun a day, in soil that is rich and well-draining, and protected from the wind. Water dahlia plants twice a week and fertilize dahlias with a low nitrogen product once a month.

Dahlias range in growing heights from miniature (which will grow 12 – 18 inches tall at most) to bedding dahlias (which will grow under 1.5 feet) and then the tall dahlias that grow 4 – 5 feet and some varieties, even higher.

There are thousands of varieties of dahlias, each with different characteristics and host of uses and benefits. For the most part, the most distinctive characteristics are in the flowers. So, we have groups of dahlias that are identified easily by how the flowers look:

  • Single – these have layer of single petals that sometimes overlap and can be either rounded or pointed on the edges. The center circle is then exposed, which is perfect for pollinators.
  • Collarette – a single layer of petals with smaller rolling petals forming from the center on top of the ‘collar’.
  • Cactus – full blooms with narrow petals that stick out like a cactus and curve outwards to look rolled from the base. These types come in a variety of sizes and some great colors.
  • Semi-cactus – similar to cactus-shaped blooms but only curved or rolled for about half the length of the petal and broader at the base.
  • Pompon – perfect little spherical-shaped flowers with neat wide petals that curve inwards.
  • Ball – similar to pompon in shape but larger blooms with a flattened top of spiraled petals. The petals are also slightly more pointed.
  • Waterlily – double flowers with petals that curved upwards, making the whole effect just like a waterlily.
  • Anemone – a ring of flat petals around the base holds a ball of cylindrical petals that stick out like an anemone.
  • Decorative – flat broad petals flow from the center outwards into a ball shape. The largest of the dahlias with blooms up to 10 inches in diameter.

Best Tools For Cutting Dahlias

Best Tools For Cutting Dahlias

When it comes to cutting flowers for the vase, always use the right tool for the job. Invest in a decent pair of pruning shears or floral snips for cutting dahlias. They need to be kept sharp so as not to damage the stems or your hands, and they need to be kept clean so as not to pass any pests and diseases onto any other plants.

When you have finished cutting, wash with clean soapy water and dry thoroughly every time. A spray of multi-purpose lubricant will keep the blades in good order. Get them sharpened by a professional.

When to Cut Dahlias for Cut Flower Arrangements

Cut dahlias often for the vase to encourage new blooms and deadhead the blooms that have faded on the plant too.

As with most cut flowers, the best time to do this is in the cool of the morning. After the cool night air, the stems will be filled with water and carbohydrates and will be firmer. Later in the day, the stems start to dehydrate, and by midday, the plants are pretty stressed. By cutting in the morning (or even in the cool of the evening), you will get flowers at their best and with enough water in their stems to last a while.

Step-by-Step Guide to Cutting Dahlia Flowers

A person cutting a purple dahlia flower in a garden
  • Cut only as much in length as you need for an arrangement or bouquet.
  • As much as possible, cut above a leaf node so that the plant can shoot from that point and produce more blooms.
  • Cut blooms that are open or close to open. Buds will not open in the vase. Avoid cutting blooms that are fully open, as they won’t last long in a vase.
  • Cut the stems horizontally off the plant.
  • After cutting, place in warm water as soon as possible and prepare the hot water treatment as described below.

Post Cutting Care

A floral arrangement composed of fresh cut dahlia flowers in a vase

Give dahlias a hot water treatment after cutting to increase their vase life:

  • Prepare a container of very hot but not boiling water.
  • Fill the container with 2-3 inches of water so that the steam does not get to the blooms.
  • Make a new cut horizontally along the bottom of the stems and place into the hot water.
  • Leave the stems in the water for at least an hour.
  • Remove all the leaves at the base of the plant, making sure that none are under the water to prevent the leaves from decaying and making the water unpleasant.
  • Make sure the vase you use is cleaned properly with soapy water and rinsed thoroughly before adding water and flowers. Bacteria can last in a dirty vase and make the flowers die quicker.
  • Fill the vase with warm water. Plant stems react better to warm water than the shock of cold water, which may inhibit the movement of water in the stems and cause air bubbles. Flowers like the temperature of the water to be between 80F and 110F.

How Long Will My Freshly Cut Dahlias Last For?

With a hot water treatment, dahlias should last 4-6 days in a vase. Adding floral preservatives may increase this a little longer.

Tips To Extend The Life Of Fresh-Cut Dahlias

Red dahlia flowers composed in a glass vase

There are floral preservatives on the market that will increase the life of a cut flower. Sugar added to the water has also been used to increase the life of flowers, and the right amount can double the life of flowers in a vase. However, in the case of dahlias, there have not been any studies to determine exactly how much sugar will be the best for the flowers, so it’s best to stick to properly formulated floral preservative products. It will also include acidifiers that will prevent bacteria from growing in the water.

Change the water every few days and top up with a floral preservative. Remove any blooms that are looking limp or dying at the same time. Also, recut an inch of the stems of the remaining dahlias underwater before rearranging.

Keep the arrangement away from drafts, fluctuating temperatures, hot or cold areas, and direct sunlight.

Keep flowers away from fruit and vegetables as the ethylene gas emitted by fruits and vegetables is a naturally occurring growth hormone that will make flowers deteriorate quicker.

How Do You Preserve Or Dry Fresh Cut Dahlia Flowers?

A vase arrangement filled with fresh and dried dahlia flowers

The best choice for drying dahlia blooms is to use silica gel. This product, available from craft stores or online, is a drying agent that pulls the moisture out of the flower while keeping the color and shape of the bloom.

Use the following steps to dry dahlias:

  • Pick flowers that are the best shape and color and have no blemishes or insect damage which will be more evident once the blooms are dried.
  • Some may not dry well, so do a few more at a time than needed.
  • Leave an inch of stem on the blooms and place face-up in a container that is at least an inch or two higher than the blooms. Use plastic or metal rather than wood or cardboard to prevent moisture from coming through the container.
  • Pour the silica gel carefully over the flowers totally covering an inch or more over the top.
  • Cover tightly with plastic wrap or with a lid and keep in a cool, dry, dark spot for seven days.
  • Carefully remove the flowers after seven days. They will be dry and crisp, so a gentle touch is needed. Use a soft brush to remove any excess gel.
  • Spray blooms with hairspray or a clear spray varnish to keep their color and keep out any moisture.
  • Use the blooms as they are for decoration in a shallow dish or manufacture stems from wire and florist tape for a vase.

Wrapping Up

The richly symbolic Dahlia flower is a stunning option for a vase, and their range of colors makes them versatile and beautiful. Cutting them straight from the garden makes the effort all the more worthwhile.

Contributing Editor | | Full Bio

Madison is a writer and editor with a Bachelor’s degree in History and Political Science. She writes and photographs for various online and print publications in the gardening sphere and is the author of the book The Next-Generation Gardener.

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