Don’t rely on brown leaves

to check the health of your shrubs; scrape the stems, Tom MacCubbin writes.

Several crape myrtles and hibiscus are showing brown leaves after Irma. Are they dead?

Many trees and shrubs have damaged leaves where they attach to the stems and trunks, causing them to decline. By now you may be seeing new growths as replacements. If in doubt about the survival, do a scratch test to look for green in the stems.

Use a knife or sharp instrument to scrape under the outer layer of young stems. If you see green, moist tissue, you know the plant is alive and capable of producing new growth. With some plants the decline may be back to lower branches or the trunk. Where you can find yellow to green layers you know the plants are still alive.

My fall tomatoes took a beating during Irma. Should I prune them back, replant or leave them alone?

Irma struck after many of us planted our fall tomato crop. Luckily the plants were not too large and while the wind whipped them, they are capable of recovery. If new growth is forming, allow it to continue producing the plant while training it to a trellis. No pruning is recommended as all leaves are needed to produce nutrients for plant growth. Continue every three- to four-week fertilizer applications for plants in the ground and every other week for plants in containers.

I have a 20-foot palm that is leaning to one side. Can it be uprighted?

Your palm is very salvageable but you may need professional help for this big job. Most likely one side of the palm has to be unearthed as it is pulled into an upright position. Another option is to dig the entire palm and reset it. Establish bracing on at least three sides for good support. These supports are likely to be needed for a year or more. Give the uprighted palm new plant care.

Some of our plumbagos are looking pretty sad. Can we cut them back and will they survive?

Plumbagos have suffered summer fungal problems and now possible hurricane damage. Leaves and some stems may be in decline. If the lower stems are green to yellowish green, there is hope for saving these plants.

Remove all dead or declining portions back to healthy stems or shoots. Then apply a fungicide labeled for leaf spots, following label instructions. Some plants may have also been flooded and now suffer root rot, which is causing the decline. These plants likely have to be replaced.

Many of our hedgetype plants have grown tall and wide. When is the latest we can prune these shrubs?

With a month or two of good growing weather still ahead, now would be the time to complete needed pruning of hedge-type plants. One exception would be azaleas kept as hedges if you want to enjoy the spring blooms. Ideally all new growth of hedge plants should be mature by the arrival of winter to avoid potential freeze damage.

In the past I have purchased onion sets or bulbs from the garden center that only produce small, fresh onions. What can I do to produce the big onions?

Florida’s bulbing onions are special as they mature under short days of late winter and early spring. The most popular varieties are Granex and Grano, often found as seeds or sometimes transplants at local garden centers. Seeds are started in October and transplants added to the garden during November. From seed to a mature bulb requires about 180 days of good growth. Most bulbing-type onions are harvested in May.

We planted cannas last spring that have grown and flowered beautifully. Only recently we noticed the lower leaves turning brown. Should I expect them to die back for fall and when are they divided?

Cannas replace leaves like other plants throughout the growing season. Possibly the leaf loss has been a bit more subtle during spring and summer. The plants are much larger now and more leaves are going to be lost.

Declining stalks need to be trimmed from canna plants to make room for new shoots and flowers that continue during the fall. When the cooler days arrive, cannas develop excessive leaf spots and gradually decline to reach a semi-dormant state for winter. Plantings can be divided about any time of the year but it is usually best performed during March to establish new beds for spring.