If it weren’t for one characteristic, dahlias would be the perfect plant for the cutting garden. Their widely varied forms, shapes, colors, and sizes are endless; there truly is a dahlia for every occasion. Regrettably, they have a less-than-stellar vase life. That doesn’t mean we can’t work to make those dahlia flowers last as long as possible. 

From midsummer until frost, these plants produce a steady and spectacular supply of swoon-worthy blooms. Their long, sturdy stems add to their usefulness in floral arrangements. The best part is that the more you cut them, the more gorgeous flowers they will produce!

Now, about that vase life. Unfortunately, cutting dahlias in the bud stage is not recommended. To enjoy their full glory, they have to open on the plant. While there isn’t much you can do about this, there are things you can do to prolong their life by at least a day or two.

Here are some tips to make your dahlia flowers last as long as possible.

Harvest at the Right Time of Day

Harvest your flowers early in the morning.

As with all flowers, there is a right and a wrong time of day to harvest dahlias for your bouquets. To harvest your flowers at their absolute freshest, morning is the best time. The sweet spot is just after the dew is dry, but before the sun is overhead. 

Morning is when your dahlias will be most hydrated. They have the highest water content in their stems, and their blooms are cool and perky. If you wait until the temperature rises, your flowers will begin to feel the stress of the heat and light. That shortens the vase life. 

If you’re unable to cut them in the morning, later in the evening is the second-best time. Once the temperature drops back to a comfortable level and they recover from the heat, they will perk up again. 

The condition in which you cut your dahlias directly correlates with how long they will last. If you cut them when they’re stressed, they may perk back up for a few days, but you’re unlikely to get more than five days in a vase. If you cut them while they’re hydrated and happy, you’ll make your dahlia flowers last significantly longer. 

Choose Fully Open Blooms

Wait for blooms to open before you pick them.

There are some flowers that you can cut before they open fully, and they will continue to bloom. We call this cutting them in the bud stage. Think of roses, tulips, irises, lilies, and peonies. Cutting them in the bud stage significantly extends a flower’s vase life. 

Unfortunately, dahlias don’t open further after you cut them. If you cut them too soon, you risk missing out on their full glory. Waiting until they are fully open doesn’t necessarily extend their life. It ensures that you get to enjoy them in their most beautiful stage, full bloom!

Always clean your tools before using them.

To make your dahlia flowers last as long as possible, use a clean, sharp tool to cut them. Sanitize your scissors, harvesting snips, or pruners after every use for optimal results. Simply wiping them down with alcohol will make a big difference. 

Using a clean tool prevents the spread of diseases and harmful bacteria that can remain on it from previous use. This keeps the bacteria out of the water, where they would rot the stems and shorten the life of the flowers. 

Using a sharp tool is essential for the health of the stems. Dahlias have hollow stems. They are somewhat delicate and break easily. A sharp blade will slice cleanly through those stems. A clean cut leaves the stem open to take in abundant moisture. 

Using a clean, sharp tool also protects the health of your plant. A clean cut heals faster, preventing disease and reducing stress. It reserves your plant’s energy for new growth rather than the need to heal a ragged stem. 

Take a Vase Along

Keeping the stems hydrated prolongs their lifespan.

Any time I go out to cut flowers for a bouquet, I bring a vase of room-temperature water along. The longer your stems are out of water, the shorter their life will be. Air bubbles can form in those hollow stems, and this blocks the uptake of water. 

As soon as you cut your dahlias, place each stem directly in the water. They will start taking in water right away, which minimizes stress and makes those dahlia flowers last longer.

Re-cut Under Water

An extra trim helps the stems draw up more water over time.

For the same reason you bring along that vase of water, the next step is to bring them in and give them a fresh cut. This time, cut them while submerged in water. You can do this in a sink or bucket filled with water, or in a vase if it’s large enough to maneuver. 

Re-cutting the stems underwater prevents the stems from drawing water in and forming a blockage. It keeps the water-conducting tissues as open as possible. 

Using your sharp snips, cut the stems at a diagonal, approximately one-half inch above the original cut. Keep the stem submerged and leave it in the water until you’re ready to use it in your arrangement.

This step will make your dahlia flowers last considerably longer. It may be a difference of several days. 

Keep Them Cool

Choose cooler spots in your home to prevent wilting.

There is a reason why florists store flowers and arrangements in a cooler. Keeping them cool slows down the aging process and preserves them. It makes dahlia flowers last longer than if they’re exposed to heat, or even to the average room temperature. 

If you have an extra fridge, you can certainly store your flowers there overnight to prolong their vase life. This requires a bit more effort than I’m willing to put in, as it’s a chore to do it on a nightly basis. 

Now, if I am making an arrangement for someone else, this is precisely what I do. There is a caveat to this. If you store apples in the fridge, it’s best to avoid this. 

Apples and some other non-refrigerated fruits release ethylene gas. This natural plant hormone is responsible for ripening and thus, aging both fruit and flowers. Keep your flowers away from bananas and avocados on the counter as well, for the same reason.  

Stay Out of the Sun

Avoid areas in front of sunny windows to extend their lifespan.

Keeping your dahlias out of direct sunlight is another way to make them last longer. Truly, it’s best to keep them away from any heat source, but the sun is particularly important. 

Direct sunlight causes your flowers to dehydrate more quickly. This causes them to wilt sooner, and it prematurely ages them. Keep your dahlias out of direct sunlight, away from heating vents, drafts, and heat-generating appliances.

Shade is better as it slows the loss of water through transpiration. It reduces stress, keeping your petals perky. 

Change the Water Often

Replacing the water every few days is recommended.

One of the most effective ways to make your dahlia flowers last longer is to provide them with fresh water regularly. Even if you’ve taken all precautions to keep harmful pathogens out of the vase, they will find their way in there. Many of these pathogens proliferate in water. 

Frequent water changes prevent a buildup of these harmful bacteria and fungi, which shorten a flower’s vase life. Those pathogens deteriorate the stems, and the resulting decay prevents them from absorbing adequate water. 

Ideally, give your dahlias fresh water every day or every other day. I realize that this is a lot, but it will make a significant difference. You can add several days to the life of your arrangement if you do it right.