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--What causes stem discolouration and how to avoid it?

Stem discolouration has a number of causes that may or may not be negative. Of course, no amount of stem discolouration looks attractive in a glass vase and the flower will be viewed as old. There are various causes for stem discolouration:

  • Low pH: the optimum pH level of the vase water is between pH 3.5 and 5.5. If soft water is used, it is okay for the pH level to go down to under 4 pH in combination with container/vase products. With soft stems, this may lead to stem discolouration. This type of discolouration has no effect on the vase life because the tissue stays intact.
  • Chlorine stems on Gerbera: chlorine is often added to the container/vase water of Gerbera. This product is very aggressive to plant tissues and must therefore be extremely accurately dosed as overdosing causes irrevocably brown stems. This discolouration and deterioration of the stem tissue due to chlorine does have a negative effect on the vase life.
  • Surfactant: surfactants are often used to increase water absorption. These products dissolve the waxy layer on the stems, for example on Dianthus. Despite stem discolouration this does not affect their durability and vase life.
  • Micro-organisms: explosive micro-organism growth, such as in containers and vases holding a lot of cut flowers or especially with damaged flowers, branches and mixed bouquets, will cause discolouration of soft stems and negatively affect vase life.

What can you do?

  • Scrub and wash containers and vases before and after use
  • Prevent the growth of micro-organisms with better hygiene routines
  • Cut 5-10 cm off the stem