Q: I enjoyed your recent story on the nun's orchid. Are these plants salt-tolerant? We live in Madeira Beach and our well water has 380 ppm of salt.
A: I'd water a nun's orchid only with rainwater or cheap bottled water. Elevated sodium levels such as yours (or in the reclaimed water in St. Petersburg and Tampa) would likely be very harmful to any orchid.
Latex will do
Q: You recently wrote about painting big containers for plants. What kind of paint do you use? Whatever I use always peels off.
A: I've had good luck with two coats of ordinary white exterior latex.
Soap for black spot
Q: Many garden books talk about black spot on roses but don't say how to get rid of it. I've heard spraying roses with soapy water will help. How much and what kind?
A: I use Kirk's Castile, which you can find in many supermarkets. Or buy direct at www.kirksnatural.com or toll-free at 1-800-825-4757. It's a true soap, not a detergent.
Fungi such as black spot and powdery mildew (on squash and roses) and sooty mold (on citrus and gardenias) need an acidic leaf surface to grow on. The soap solution makes that surface alkaline, so the fungi die.
The coconut oil in the soapy water helps suffocate bad bugs by plugging their breathing holes and permeating their exoskeletons.
To make a small batch of soap spray, use a cheese grater on a bar of Kirk's to make 1 to 3 heaping tablespoons of soap flakes, then dissolve in 1 gallon of hot water in a plastic jug. Let it sit for a couple of days, shaking the jug daily to dissolve lumps. Then spray the affected plants (until they are dripping) every seven to 10 days. Use it when you don't plan to water for a few days so the soapy spray can cling to leaves.
To make a big batch of concentrate, drop a whole bar into a 1-gallon container, fill with hot water and let it sit a week, stirring daily. You'll have a thick soap concentrate that keeps indefinitely in a container with a lid. To make a batch for spraying, dissolve 1 cup of concentrate in 1 gallon warm water, shake, then pour into a spray bottle. (For tougher problems, try 1 part concentrate to 10 parts water for thicker, more potent soap spray.)
Q: What would make my iceberg lettuce bitter? I use mostly reclaimed water and blood meal, bone meal, organic general mix, manure (bagged and real). This is a new garden, atop what was once a concrete driveway. I used your conditioning regimen of dog food, alfalfa pellets and cat-box litter.
A: Reclaimed water has high levels of sodium and chlorine, so that could be one reason for your problem. The old concrete driveway may make your garden dry out faster, which could also lead to bitterness. Next winter try Buttercrunch, a reliable, sweet variety, and avoid recycled water.
John A. Starnes Jr., born in Key West, is an avid organic gardener and rosarian who studies, collects, cultivates and hybridizes roses for Florida. He can be reached at firstname.lastname@example.org.