Why does my Handkerchief Tree not flower?

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Gardeners Question Time at the Unusual Plant Fayre

On Saturday I was a member of the panel at the Unusual Plant Fayre which takes place annually at Gilbert Whites former residence, in Selbourne. If you haven’t been it’s well worth a visit to see both the house and gardens. Most unusually for me I only bought one plant! There were plenty there which I would have liked though but I’m going for quality over quantity in my home garden.

One of the more universally applicable questions was about a tree which has only flowered once in it’s life and isn’t flowering every year as one would expect. It is a Dove Tree, aka Ladies/Gentlemens Handkerchief Tree or Ghost Tree. That’s why we have Latin names, too many variations of common name can cause confusion. Were talking about Davidia involucrata.

Any tree or shrub needs to produce ripened wood to produce flower. Sometimes that means the whole plant needs a few years to get big enough but this tree had already flowered once and was about 20 feet high.

Producing ripe growth which can give rise to flower buds requires two things in general; an adequate amount of ┬átime in the sunshine and the presence of an adequate amount of Potassium in the soil. If you prune too late in the season then the new shoots don’t get enough time to get matured by the sunshine so it’s worth checking when and how to prune any tree or shrub.

Generally it’s straight after flowering and not all of it at once but about a third each year to maintain vitality. That is more shrubs than trees although most of the time our shrubs are just trees which we keep small with the regular pruning (or not as the case may be!). Most trees are best left un-pruned and allowed to reach their natural shape, if you have enough space.

A deficiency of Potassium can be down to there not being enough in the soil or simply that what there is in the soil is not available to the plant. This goes for other elements which plants need like Calcium and Iron. Watering on Potassium Sulphate (or Sulphate of Potash) could be a solution (no pun intended!). Improving the trees general growing conditions might be enough in itself though.

Apparently there were some conifers nearby which had been cut back the year that the tree flowered. It’s most likely therefore that they were taking the majority of the water which is essential for taking up nutrients from the soil. A lack of water combined with competition for light and nutrients from the conifers was probably enough to mean that the Davidia could not manager to produce flowers.

Watering on Potassium sulphate can help though in many cases and is not likely to do any harm provided you are following the suppliers instructions. A general feed high in Potassium could cover some other possible deficiencies. You can make your own general purpose feed by putting whole Nettles, Comfrey leaves and/or wood ash in some water for a couple of weeks and diluting it with plenty of water.

Wood ash is very high in Potassium and this where the element got its name, from Pot Ash.