‘Reverting’ Hostas
A very common question is ‘Why do my variegated hostas sometimes come up with plain green (or blue) leaves? And what should I do about it?
The ‘catch-all’ term for this change is ‘Reversion’. This means a hosta ‘reverting’ to one of its solid colour ancestors. Virtually all variegated hostas are cultivars and at some point in their ancestry were unvariegated.
Occasional ‘reversion’ is common to many varieties of hosta and some varieties are more prone to it than others. Most often it will just be one or two eyes (leaf buds) that revert. In extreme cases the whole plant may lose its variegation.

However, the green or blue leaves may not be a true reversion. If a variegated hosta produces blue or green leaves it may be a ‘sport’, a mutation or new variety. The hosta may simply be helping itself to survive. A green or blue plant contains more chlorophyll and tends to be more vigorous than a variegated plant. A blue hosta, incidentally, is still a green hosta. The ‘blue’ coloration is a waxy coating on the green leaf that reflects blue light.

What to do about ‘Reversion’.
If the problem is just occasional reverted leaves then all you need to do is to remove them at the base of the plant. If, however, you trace the leaves down to their base and find a whole shoot or section of the plant has turned green or blue, then you will need to cut out the piece, including its crown and roots. If you leave the shoot, you may find that eventually the whole plant will revert and you have lost your variegated hosta.
George Schmid, author of ‘The Genus ‘Hosta’, says that all variegated cultivars will eventually lose their variegation even if it takes a human lifetime for them to do so!

There are many hostas on the market which are solid-colour sports of their parent, e.g. H. ‘Greenie Weenie Bikini’, an all-green sport of the variegated H. ‘Teeny Weeny Bikini’. So, before you discard the affected part, check your Hosta’s parentage. This web page helps: https://www.myhostas.be/sports/index.htm If the ‘reversion’ is attractive and you feel it is worth saving, then you can pot-up the cut-out piece (leaves, crown, and roots) and you have a new hosta.