Hydrangeas are beloved cut flowers, recognizable for their dense, globe-like blooms that add volume and color to any arrangement. Despite their beauty, they have a reputation for wilting quickly after being placed in a vase. This rapid decline is due to their immense thirst, which, when interrupted, causes the large flower heads to droop almost instantly. Successfully maintaining cut hydrangeas requires understanding this high-demand hydration system and employing specific conditioning techniques.
Understanding the Hydrangea’s Thirst
The size of a hydrangea’s bloom and foliage is the primary reason for its high water requirement. The expansive surface area of the leaves and petals results in a high rate of transpiration—the process of water evaporating from the plant’s tissues. If water loss exceeds the water uptake through the stem, the flower wilts.
The plant’s vascular system, the xylem, transports water but can be easily blocked. When the stem is cut, the plant releases a sticky sap that clogs the xylem tubes. If the stem is left out of water, air bubbles can enter the xylem, creating an embolism that interrupts the flow of water. To maximize longevity, remove excess foliage from the stem, as leaves contribute significantly to the high transpiration rate.
The Critical Initial Conditioning Period
The initial conditioning treatment, performed immediately after cutting or purchasing, is the most important step in extending the life of a cut hydrangea. Use a sharp knife to recut the woody stem at a 45-degree angle; this maximizes the surface area for water absorption. Because the woody tissue can be tough, some florists recommend making vertical slits up the last inch of the stem or gently crushing the end to expose the xylem tissue. Immediately place the recut stems into lukewarm water, which helps prevent air from entering the vascular system and encourages faster initial water uptake.
Once the stems are prepared, deep soaking or full submersion may be necessary to fully rehydrate the blooms. If the flower heads are showing signs of wilting, submerge the entire bloom and stem into a sink or tub of cool water. The petals and leaves absorb water directly through their surface, quickly restoring turgidity. Soaking time can range from 15 minutes to several hours, or even overnight, depending on the severity of the wilting.
Specialized Stem Treatments
Two specialized techniques can be used for robust conditioning of the stem end. The first involves dipping the freshly cut stem into alum powder, a common pickling spice, for about half an inch before placing it in the vase. Alum helps keep the cut end open and prevents sap from clogging the water channels.
A second method for clearing a suspected sap blockage is the boiling water dip. Place the bottom one to two inches of the stem into boiling water for about 30 seconds. The heat dissolves the resinous sap, clearing the pathway for water before the stem is immediately transferred to room-temperature water.
Daily Maintenance for Extended Vase Life
After initial conditioning, routine care is required to ensure the bloom’s lasting vibrancy. The water in the vase should be replaced entirely every one to two days to prevent bacterial proliferation. Bacteria multiply quickly, forming a slimy film that clogs the stem’s vascular system and leads to renewed wilting.
The stem ends should also be recut every few days, removing about a half-inch of the stem at an angle. When changing the water, use a fresh solution that includes a commercial floral preservative. This preservative serves a triple purpose: it provides a food source (sugar), acidifies the water to improve uptake, and contains a biocide to inhibit bacterial growth.
Placement and Revival
Where the flowers are placed significantly impacts their longevity. Hydrangeas wilt rapidly if placed in direct sunlight or near sources of heat, such as radiators or electronic devices. A cool, shaded location is preferable to slow down the rate of transpiration. Keep the arrangement away from ripening fruit, which releases ethylene gas that accelerates the aging and wilting process. If a conditioned flower begins to droop again, immediately re-condition it by submerging the entire bloom in water or by performing the boiling water dip to clear any new clogs.