Q: Some of the leaves on my camellia have turned brownish-gray on the top, but are green on the bottom. In places where there are leafless stems, some leaves are starting to fall. What should I do?
A: Even the healthiest camellias can develop blemishes on the leaf surface. Usually this is the type of gray to brown algae leaf spot you described. These fungi and algae combinations often grow on shady leaves in areas with poor airflow.
Algal leaf spot usually causes minimal damage and occurs on older leaves that fall from camellias within one to two years. Fungal leaf spots and diseased stem areas may also occur and may contribute to plant decline.
Many of these blemishes and declines can be alleviated by allowing the plant enough space to grow. Overhead pruning may be necessary, but will not completely remove shade. Camellias like sunlight filtering through the trees.
Prune dead stems and apply a copper fungicide according to label directions to reduce foliar algae and diseases affecting camellias. Repeat applications may be required.
Q: I love hydrangeas, but I haven’t had much success growing them as big and flowering as we do in northern states. I bought two new plants for an area that gets sun in the morning and shade the rest of the day. Is it the right lighting for them? Do I like pink or purple flowers instead of blue? When should I add lime to make it pink?
A: In central Florida, hydrangeas have a hard time looking like they do in the north. Intense sun, periods of dry weather, and prolonged summer heat and humidity pose challenges for local producers. We chose an ideal location with sun in the morning and shade for the rest of the day. A location that receives sunlight all day is also ideal. Next, you need to provide moist, alkaline soil to sustain the plant’s growth and pink flowers. Successfully plant in areas rich in organic matter. This helps keep the soil evenly moist. Next, test the soil for acidity. I’m looking for soil with a pH of 7 or higher. Sprinkle lime if you need to raise the pH level. If needed, use a small amount, no more than 1 pound per 10 square feet. Make sure the root ball is wet every time you water and keep the soil moist. Feed with a slow-release fertilizer in March, May, and October according to label directions.
Plant Doctor: Further help for freeze-damaged plants — next up are kaffir lilies, shrubs
Q: One of my bushes appears to have small Spanish moss growing on it. Are there any negative effects on plant health?
A: In most cases, Spanish moss does not affect trees and shrubs that grow in local landscapes. Use the plant as a coat rack for support while getting water and nutrients from the air. Residents often think it’s part of the normal Florida look. In some cases, moss can outgrow landscape plants. One example is crape myrtles. Spanish moss and crape myrtle seem to have a love-hate relationship. If the crape myrtle is not growing well, moss can take over and hide the foliage. In this case it must be deleted. Otherwise, most plants with moss will happily grow together, so you can ignore the moss.
Q: There are black spots on the leaves of my azalea. I know what the problem is, but can I apply the controls?
A: Some leaf spots are quite common in plants, but azaleas seem to have developed them. The most common is Cercospora spots, which begin to affect the leaves of azaleas during the summer. It is worst on plants that are protected from good air flow, which keeps the leaves excessively moist. Some leaf spots are normal and can be ignored. Control is required when fungal leaf spot becomes a major problem, causing many leaves to become damaged, yellow, and drop prematurely. Choose a fungicide labeled for leaf spot and start spraying at the beginning of the rainy season. If necessary, continue monthly until fall, following label directions.
Q: When I started cutting the dead flower stems of my amaryllis, I noticed one stem with what looked like a bulb attached to the base of the wilted flower. Can I save and plant these bulbs?
A: Take advantage of this opportunity to grow more amaryllis. However, grow it from seeds, not from bulbs. What you noticed is a capsule containing seeds. Once they turn yellow and begin to split, harvest the wafer-shaped seeds and sow them into your potting mix. Using a shallow tray, sow the seeds in about a 2-inch layer of soil. Cover them lightly and keep them moist and they will germinate in about 2 weeks. Continue watering when the surface begins to dry and grow in a sunny location. Once the seedlings continue to grow, transplant and fertilize every 4 to 6 weeks during warmer months. This adventure in growing flowering plants takes about three years to produce flowers.
As May approaches, here’s a Central Florida gardener’s to-do list
Q: Some of my mature spruce trees are dying. What’s the problem?
A: Older spruce trees are more susceptible to what pathologists call canker. These are usually fungal infections introduced through wounds caused by pests, pruning or bending of the limbs of the tongue. The pathogen is usually a weak type, but it can affect older shrubs. The only cure is to immediately prune back any dead or declining parts to a healthy tree. It is best to amputate these limbs at least 6 inches from where the affected limb or trunk is found. After pruning, apply a copper-based fungicide or similar product according to label directions. Also, make sure your spruce tree is kept moist and fertilized with a slow-release landscape product two to three times a year.
Tom McCubbin is an emeritus urban horticulturist for the University of Florida Cooperative Extension Service. Write to Orlando Sentinel, PO Box 2833, Orlando, FL. 32802. Email: TomMac1996@aol.com.
