I had this problem some years ago. Turned out to be a magnesium deficiency. Here's what one expert says: "I'm seeing geraniums with red lower leaf margins, which progress to interveinal chlorosis. There could be several causes of these symptoms (which makes accurate diagnosis difficult when you only have symptoms to work with) including cold temperatures, holding the plants very dry for a long period, root problems and magnesium deficiency. The only way to confirm magnesium deficiency is by foliar or media analysis. But if you don't have magnesium in your water, don't have dolomitic lime in the media, aren't applying a fertilizer incorporating magnesium, and feeding predominately calcium and potassium, the problem probably is magnesium deficiency. Even if you have magnesium in the media, high levels of calcium and potassium can interfere with magnesium uptake and the plant shows magnesium deficiency symptoms. Because of this interaction, you need to look at the balance between these three nutrients. There should be adequate uptake of magnesium when the percent of total soluble salts (saturated paste media analysis technique) for magnesium is above 4% with calcium between 14 to 16% and potassium between 11 and 13%. One application of Epsom salts at 8 to 16 ounces per 100 gallons will usually bring the nutrient balance back into line. Don't over-apply magnesium because high levels can interfere with calcium and potassium uptake, although it would be rare. Remember by the time you see symptoms, the plants have lost growth and quality that they won't regain. Don't guess. Media test." -Michigan State University

Well I looked up my notes, I started my geraniums 1/27/07 I am at 6 to 8 leaf stage. I started 1/2 strength fish emulsion at 2 leaf stage. This week I am using 2x's per week general purpose fertilizer. I use potting soil for the transplant to geranium pots. I would give them some fish emulsion fer sure in the next watering. Soiless mix has no nutrients. If you think they aren't too far gone I would transplant to a better soil medium also. I applaud your efforts, in the middle school my daughter attends the gifted program planted spring bulbs outside for their project this year, how lame is that? It's nice you have such a large lighted or sunny area at your school too!

I have pink geraniums in hanging baskets on a sunny porch. They start out great and then the leaves begin to turn brown at the edges, curl up and stems break off leaving a very anemic looking plant. Is this a blight, bug, or fertilization problem? Thanks.

Kelly: My order from RU also comes this week: Poisedon, Munstead Wood, Dee-lish, and Lady of Shalott. Granular gypsum is sold cheaper at feed-store or at Menards at $4.59 for 25 lb. bag. Despite being next to a limestone quarry, my soil-test came back barely adequate in calcium , due to calcium bind up with magnesium and phosphorus at high pH. Gypsum made a BIG DIFFERENCE in my tomato. For many years my cherry tomato would crack in rain, then it gets mushy & watery at hot temp. After using gypsum, my cherry-tomato are firm & crunchy & thicker skin and no longer crack with heavy rain. If the bottom of the hole is too hard to dig, I put gypsum, pour in some water, take a break. When I come back, the 17% sulfur in the gypsum soften the hard-clay at bottom, so I can dig deeper for drainage.