Expert: C.L. Fornari - 8/6/2006

Question
No, thank goodness there's no mildew.  The leaves are just drained of color.
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Followup To

Question -
My geranium's leaves both types (ivy and zonal) are turning white and the buds are not maturing.
I use both Osmocote and Miricle Grow.  We live in Oklahoma and are averaging 102 for the past month consequently I have to water every day, sometimes twice on my mixed pots.  All but one of the ivy geraniums are in full sun from 11am until dark.  All pots are in pots.
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Thnaks for any help

Answer -
Angela,
It sounds like your geraniums might have mildew - are the leaves just white as if they are drained of color, or are they white with a powdery coating?  If they are white with a powdery coating, that is mildew, and plants get it when the air is humid and low air circulation.  If plants are watered in the evening so that the leaves stay wet all night, that can contribute as well.  Mildew will also cause the buds not to open.

If the entire plant is effected, you may not be able to save them, but you can try spraying with a fungicide that is labeled for mildew - unfortunately, many fungicide labels say not to spray in hot, sunny weather, because the spray makes the leaves more sensitive to heat and sunlight, so read the labels carefully.

I don't know if you can find it in your area, but there is a least-toxic fungicide that is very effective for mildew called Green Cure.  It is potassium bicarbinate (similar to sodium bicarbinate that is baking soda) and I've found that it stops mildew in it's tracks when used every ten days to two weeks.  I had to order it online (google "Green Cure fungicide" and you'll find sources) but you might find it locally.

In the future, when you water, stick the hose under the leaves and water the dirt only so that the leaves don't get wet.  Clip off any diseased looking leaves quickly to slow spread of fungal problems, and make sure that boxes and baskets aren't so packed with plants that there is no air circulation...hard for out-of-control plant people like me to do, but if you live where it's hot and himid it can keep plants in better shape.  

If you think that mildew isn't your problem, write again and we'll problem solve from there.

all the best,
C.L.  

Answer
OK - good that it isn't mildew.  The two things that I know of that can drain foliage of color are salt toxicity, and being too root bound.  Salt toxicity in this case would be from a build up of too much fertilizer in the soil - flush the boxes or pots well with water a few times, and stop any liquid feeding.  Is the soil new this year?  If you used soil that you had planted in last year, it might have already had salts built up from last year's fertilizer, and when this year's was added, it took it all over the top.  Too much fertilizer will also stop a geranium from blooming.   

I have also seen plants that are very very root bound develop white foliage - the roots are so thick and crowded in the bottom of the pot that there is not any room for soil, so the water and nutrients pass right past the roots and out the bottom.  If you think that this is the case, you can either try repotting, or if that is impossible, try top-dressing plants with earthworm castings and watering with a weak solution of fish-seaweed emulsion and see if this helps.

It is possible, of course, that a combination of these two problems exists....but looking on the bright side, at least it's not mildew, which is harder to remedy.

I hope this helps!
C.L.
C.L.