Ed ,you never can tell with variegation , if it is stable ;-) rumour has it the Thais have a magic wand they share amongst growers , they sacrifice virgins and burn chicken feathers and submit seeds to radioactivity and most importantly they grow millions of seedlings , the odds are one will turn out variegated . I got one variegated seedling from tens of thousands of Vriesa splendens , but it was very unstable .. 15 cms and it all went !

There are several different possibilities for the change in variegation. One is that the presence/absence of light and its intensity and wavelength affects the chloroplasts and the chlorophyll that they contain. Depending on the particular problem (genetic) in the chloroplast light can bleach the chlorophyll making it whiten or it may help it and the cell becomes greener. Another aspect is that each plant cell (in most species) has many chloroplasts. Variegation can be due to a plant having two types of chloroplasts, normal and abnormal with the abnormal having less or no chlorophyll. As the plant leaves developed and cells divided some may have received different proportions of normal and abnormal chloroplasts. The cells will then be different shades of green (or yellow or yellow-green or cream) depending on the number of chloroplasts and how much chlorophyll they have and the background pigments). The abnormal chloroplasts may age differently and be destroyed by light or depending on the type of mutation they might actually recover due to light and become green. The original mixture of cells would be one overall shade and after a time, with certain cells losing or gaining colour the overall colour of the mixture could change. Also possible is that if a cell has abnormal chloroplasts then the light that is received actually damages the cell (because normal chloroplasts contain pigments to transfer some energy to less destructive uses and abnormal chloroplasts might be too disrupted to do that but still absorb the energy). The cell becomes bleached, and dries out.

You planted a variegated hydrangea in zone 4b? Is it a macrophylla?...If so, the yellow leaves will be the least of your problems as it will most likely not survive winter anyway. Sorry to be so blunt, but this plant is not hardy in the ground in 4b. If you pot it up and winter protect it in a shed, barn, garage, unheated room, etc., you might get to enjoy it for more than one season.....yg

You can used the faucet (especially if you have a set-up with a hand sprayer). Make sure the water temp is well below body temp, which is too warm. If you suspect the soil has been adulterated with something phytotoxic, you have little choice other than to flush the soil and then try to mitigate any subsequent tendency of the soil to retain too much water. Look at B and E to see how much excess water you can remove by tipping the pot and using a wick. Also, if the pot is a 7" pot, you can hold it over the sink and move it down then sharply upward to rid the soil of virtually ALL excess water. Think of what you do after pouring pasta in a colander - after it stops draining. You grab the colander and move it up and down to remove LOT of additional water. Do that with your little plant. If more growers applied that technique they would help their plants realize significantly more of their genetic potential. The pot should be detached from the reservoir, and the plant should never rest in the effluent that exits the drain holes. The purpose of flushing the soil when we water is to rid the soil of an increasing level of mineral salts from tap water and fertilizer solution. If the plant rests in its effluent, the level of salts very quickly reaches a state of isotonicity (balance in the salt levels between the water in the collection saucer and the soil solution), which in the end is like the soil was never flushed at all. Al