Q: I’m having trouble with my potted geraniums.
Too many of the leaves looked injured. They wear sunken spots that are a papery gray color. The plants are getting ready to bloom so I don’t think they need fertilizer and I water every fourth day. Do you have any ideas as to what is happening to the leaves to make them look so bad? – G.G., Albuquerque
A: I think I have an idea about your geraniums. Years ago at the nursery where I began this sojourn, a customer brought in a sample of leaves from her plant that was suffering from what sounds like the same malady. Mr. Jim Sais was on staff as one of our many teachers at the time and he explained that the sickly leaves could be caused by inappropriate watering habits.
Imagine the plant this way: You water and the plant “inhales” the water it needs. The water is sent and stored within the cell walls of the leaf. Then as the plant dries out it uses up all of its stored water within the cells and the plant gets that floppy, softened look, which is your cue to water. You do water, and think all is well with the world.
Meanwhile, the geranium is “inhaling” water as quickly as it can to refill itself. Now, since some of the cell walls have been weakened because the plant dispersed so much of its stored water and was allowed to dry a bit too much, some of those weak cells sort of explode while they are trying to refill. It’s that internal injury that shows up as that papery, sunken-looking spot.
But don’t despair, this fix is an easy one if this is the trouble with the geranium. Just water a bit more often. Take the water you usually give on the every fourth day watering and split it to an every two day watering. The cells will stay fuller and the plant won’t “inhale” as desperately as it’s been having to.
The only other cause I can think of might be the time of day you are watering, although I really think the spotting is caused by cell collapse. If you are watering from overhead and any water droplets are sitting on the leaf surface as the sun climbs into the sky the light could be magnified through the droplet, burning the leaf surface underneath.
That’s why it’s recommended watering very early in the morning before the heat of the day comes on. A dry leaf surface during daylight hours, especially very sunny ones, is healthier.
But again, I think it’s the stretch between watering that is the cause of this malady. For now, snip off the damaged leaves so no other disease is encouraged, switch up your watering and I’ll bet you’ll see marked improvement on the plant as a whole! Happy Digging In.
OK, Albuquerque! Are you ready for all things tomato? Then the Albuquerque Area Master Gardener event – the 2014 Albuquerque Tomato Fiesta – is where you need to be! From 11 a.m. to 3 p.m. Sunday at the Albuquerque Garden Center, 10120 Lomas NE, your master gardeners will show off their love for those marvelous globes of flavor.
For a nominal admission fee, you can partake of several seminars, heirloom tomato tastings, plant clinics, live music, a gardening trade fair, kids’ activities and a produce sale featuring the season’s bounty, and what else? Tomatoes! Have fun!
Need tips on growing your garden? Tracey Fitzgibbon is a certified nurseryman. Send your garden-related questions to Digging In, Rio West, P.O. Drawer J, Albuquerque, NM 87103.