The variegated vinca growing in light shade in my garden has lost its white borders. Should I move it to a sunnier location?
The technical term for a loss of variegation is reversion. Variegation can be affected by light conditions as well as other factors, as this information from the Royal Horticultural Society suggests: “Variegation may vary during the year and is often less apparent in late summer. Where there is a permanent loss of colour inadequate light is often the cause. Waterlogging can also lead to loss of leaf colour. Reversion may also occur where more vigorous green shoots outgrow variegated shoots.”
Here is a link to some helpful information about variegated plants, from a now-defunct website which was called Enjoy Gardening:
“Understanding all the science behind variegation is quite complicated, so here is the nutshell version. For variegation to be stable, the variegation trait must be caused by a mutated cell or a group of cells that are fit
enough to grow and multiply, and those cells must originate in a region of the plant where they are involved in generating new variegated gene cells. For example, if the mutation originates in a section of a leaf or stem where normal tissue can outgrow the mutation, the variegation pattern will often be unstable and disappear. However, when there is an ‘island’ of mutated cells within a growing point or tip, the variegation has a greater chance of
being stable… Of course, to every set of rules there are always exceptions, which is why it’s quite common for completely stable varieties of plants to lose their patterns over time. And that’s exactly what happens with some
variegated Euonymus shrubs when the ‘normal’ buds produce leaves that have more chlorophyll than the variegated leaves have. Having more chlorophyll allows the normal leaves to grow faster and to out-compete the variegated foliage. In this case, the solution to preserving variegation is to get out the pruners and to lop off the emerging threat of normalcy.”
As suggested above, you can try cutting off the non-variegated (‘normal’) foliage and hope that the variegated foliage will return to dominance.