Spring Cleaning in Your Landscape

Theresa Badurek
Urban Horticulture Extension Agent

Timing
Spring is here, and that means it’s time to prune many plants. There are a variety of reasons to prune, but the most important thing is to do it right. Part of that is having good timing. Pruning should be a regular part of your landscape maintenance and should not be put off until the landscape is overgrown. Overgrown plants may grow tall and leggy with little foliage near the ground. Once you wait this long they cannot be pruned to the desired size in a single pruning without severely damaging the plants. These plants will need to be pruned back gradually over a period of several years. So, keeping up with maintenance pruning is step number one.

Cold Damage
You can now prune those woody plants that were damaged by our few nights of freezing or near freezing temperatures. You will want to watch for new leaves sprouting along the branches and prune back to this point. Take care to maintain the natural shape of the plant; when correct pruning is done it should not be noticeable that you did it. You may find that some of your more cold sensitive plants will need to be pruned back to the ground. It will take them a bit longer to recover, but be patient.

Flowering Shrubs and Trees
Once azaleas, poinsettias, and camellias finish flowering they should be pruned. Pruning encourages new growth and produces a more compact, bushier plant. There is still time to prune out dead growth and crossing limbs on crape myrtles, but try not to remove the new sprouts since the flowers will be forming on this year’s new growth. Contrary to what you may have heard, pruning is not necessary for crape myrtles to flower. Simply prune them lightly to maintain a natural form. If necessary, heavy pruning of hibiscus is best done now as well. The new growth should produce flowers in about five to six weeks. Light maintenance pruning may be done any time of year to keep plants at desired heights.

Fruit Trees
One should always remove suckers below the bud or graft union on citrus, avocados, mangos, or any other grafted plant. These shoots will grow fast and rob much needed nutrients and water from the desirable upper portion of the plant and will not produce the desired flowers or fruit.

Palms
Only dead fronds should be removed from palms. Palms put on an average of one new frond per month during the growing season, although this varies greatly from one species to the next. The reason for mass removal of healthy green fronds is because it is more convenient for the pruner to remove everything and not have to prune the tree again for 6 to 12 months. It is not healthy for the palm. Constant leaf area removal results in damage and decline and eventual death of the palm from weakening. Do not let anyone talk you into removing more than the dead fronds or you may be contributing to the death of your palm. The “hurricane cut” you hear about for palms will actually make the palm more vulnerable to damage in the event of a hurricane or wind storm.

For More Information
Consult the University of Florida/IFAS Extension publication, Pruning Landscape Trees and Shrubs on the Internet at: http://edis.ifas.ufl.edu/MG087 for additional detailed pruning information, including techniques, illustrations, and time of year for pruning all kinds of trees and landscape shrubs.

It’s Hurricane Season – Are your trees in shape?

By Pam Brown, Urban Horticulture Agent, University of Florida/IFAS Pinellas County Extension

As hurricane season arrives, there are many tree companies that are out and about offering to prune large trees and palms. Much of the pruning that is done can actually create a situation that puts the tree in more danger of failing in high winds than of providing protection. There has been a lot of research done at the University of Florida on the proper way to prune trees and the way that trees behave in high winds.

First, allow me to provide a bit of biology 101 refresher. The green leaves on trees and the green fronds on palms are the source of the food, through the process of photosynthesis, that these plants need to thrive and grow. When you remove green leaves and fronds, you reduce the ability of the plant to produce the food necessary to support the roots and top growth adequately. Fertilizer contains nutrients that are necessary for making proteins and enzymes but it is not the source of the food necessary to sustain the tree.

Let’s look at palms since they are so often badly pruned. When green fronds are removed, the palm is weakened. And, when all but a few of the fronds are removed in what is commonly called hurricane pruning, the trees is in more danger of failing in the wind. Those lower, fronds are mature, hardened fronds that protect the newer, more fragile fronds near the growing point of the palm. Without the mature fronds for protection, the top of the palm is more likely to sustain wind damage during hurricanes or other high winds. In addition, when this type of pruning is continued over time, the palm is weakened and may develop nutrient deficiencies and eventually decline and die. Palms are pruned primarily for people reasons and not the health of the palm. It is perfectly acceptable to remove dead fronds and blooms or fruit. And, I find that when a frond is hanging too low over the sidewalk, just cutting off the tip end of the frond will make it light enough to spring up out of the way of pedestrians. Removing the frond bases that remain attached to the trunk with a chainsaw creates wounds where insects or disease can possibly enter.

Our large shade trees are also being damaged by improper pruning. According to Dr. Ed Gilman of the University of Florida, this common malpractice on large trees of removing many or all interior low branches is considered over-thinning or “lions-tailing”. He states that “When people prune trees in this abusive manner, excessive live tissue is removed from the tree and no structural pruning is performed. This creates poor form and numerous wounds, and the tree becomes more prone to failure especially if there are few trees nearby. Old trees can decline as a result of removing too much live tissue. Only a small amount of live tissue may be too much to remove on a mature or over-mature tree. There should be a very good reason, such as to reduce likelihood of branch failure, when removing more than ten percent of the live foliage on mature trees.” Also, please do not allow anyone to top your trees for any reason.

Reducing the amount of foliage on the ends of the branches, and thus the weight, is a better way to reduce risk of branch failure during high winds. The canopy can be opened up without removing all of the interior branches and attached foliage. An arborist certified by the International Society for Arboriculture is trained in the proper way to prune and protect trees. However, all certified arborists are not equal. When requesting a quote from an arborist, ask to see their certification card, proof of liability insurance (ask for this no matter who you hire), references, and also ask if they will be with their crew when the work is done. I would suggest three quotes and then maybe even go to look at some trees that they have pruned.

You can find certified arborists in our area on the Internet at: http://www.treesaregood.org/findtreeservices/TCSHome.aspx. Or, you may call our Lawn & Garden help line (582-2110) Tuesday – Thursday and request a copy of the current list.

The following links lead to the extensive University of Florida information on tree pruning on the Internet:

http://hort.ifas.ufl.edu/woody/pruningpalms.html, http://hort.ifas.ufl.edu/woody/pruning.html

http://treesandhurricanes.ifas.ufl.edu/

In addition, you can view a 50 minute video called “Trees and Storms” on the Internet at: http://pinellas.ifas.ufl.edu/lawn_garden/index.shtml. Go to the right side of the page under "Hot Topics" and click on “Trees and Storms”.

Trees add considerably to the value of our property and keeping them healthy while providing protection from damage to our homes is a delicate balance that requires planning and caution. I hope that you will do your homework before allowing just anyone with a truck access to your trees.

Timely Tips for March – Part 1

By Andy Wilson, Pinellas County Extension Horticulturist

This winter has brought us many warmer than average days as well as one night of below freezing temperatures that damaged some kinds of plants. March marks the end of the danger of any plant-damaging cold and many plants will be producing lots of new growth now. Here are some lawn and garden tips for March.

Cold Damaged Plants- Cold damaged woody plants can be pruned now. New growth may be already emerging, making it easier to determine where the wood is alive, if there is any wood that was killed by the cold that needs to be removed.

Pruning Hibiscus- Even if they were not seriously damaged by cold this winter, now is a good time to prune hibiscus if needed. New growth can be expected to come out quickly after pruning. Use sharp tools of the proper size for the size of the branches you need to remove. Hand pruners are used for branches less than ¼” diameter and pruning saws are used for larger branches. More information on proper pruning methods can be found here: http://edis.ifas.ufl.edu/MG087

Cannas- Cannas are easy to grow in Florida. Prized for their large, showy flowers borne at the ends of the stems, they are also valuable in the landscape for their bold green, maroon or variegated leaves. To keep the plants growing vigorously it is helpful to lift the thickened rhizomes from the soil, prune away the older, depleted parts and replant them. This can be done now. Cannas should be fertilized about once a month. More information on growing cannas can be found here: http://edis.ifas.ufl.edu/MG030

Leaf Drop- Over the next several weeks many broadleaved evergreen trees and shrubs will drop varying amounts of old leaves. Usually the leaves will discolor to some extent before dropping. This kind of leaf drop is common on Southern magnolia, hollies and many others. This is a natural process, and doesn’t mean that there is anything wrong with the plant.

Oak Leaf Blister- Soon after the new leaves of laurel oaks and water oaks appear this spring you may see puckered spots in the leaf tissue. Some of the affected leaves may drop. This usually is an indication of oak leaf blister, a common fungal disease of oaks. Although spraying beginning when the new growth begins to emerge can be used with varying degrees of success to control the disease, it is usually not worth the trouble and expense to do this. The disease is strictly cosmetic and does not threaten the real health of the tree. Live oaks, with their more leathery leaves, have little problem with oak leaf blister.

Mangos- Continue spraying mangos with a copper fungicide once a week until all the fruit has set, then continue spraying once a month. This will help to control anthracnose, a very common disease that can attack the flowers, small fruits and new leaves.

Stay tuned until tomorrow for more tips on aphids, bananas and palms, plus other timely gardening information.

It’s Time for Spring Clean-up in the Landscape

By Pam Brown, Urban Horticulture Extension Agent

The end of February and into March brings much warmer weather and plants in our landscape start to spring forth with new growth. This is the time of year when we want to refresh the landscape by removing any damage that was caused by cold weather, cleaning up leaves and other plant debris that collected under plants during the winter, planting annuals for spring and summer, and applying a fresh layer of mulch.

Now is the time to look at those plants that were damaged by the recent freeze that we had in most parts of the county. Plants that lost their leaves should be sprouting now. Prune these plants back to healthy sprouting buds that are growing to the outside of the plant by making pruning cuts at a slight angle about ¼ inch above the bud. Some plants may be only sprouting from the base or roots of the plant and you will need to prune the stems back to this growth area.

Cleaning up leaves and other plant debris that have fallen to the ground and removing diseased leaves and fruit is perhaps the single most important thing you can do to manage many of the leaf-spotting, powdery mildew, bud and flower blight, and canker fungi. This is because many of these fungi overwinter on plant debris. When this fungi produces spores, wind, irrigation and rain can disseminate them to other areas of the garden or landscape. Camellias and azaleas are susceptible to petal blight causing the flowers to turn brown and rot prematurely. All fallen buds, flowers or petals should be removed from under the plants as soon as possible. On camellias especially, if buds or flowers turn brown on the plant, remove as soon as you notice them. Keep your trash can or bag near by to avoid carrying infected debris across the yard.

Contaminated tools can also contribute to the spread of disease. Tools used to prune plants infected with witch's broom, canker, gall and other diseases should be disinfected after each use by dipping the cutting surfaces in a solution of one part bleach to nine parts water. Rubbing alcohol (70%) from the drug store will also work and does not require diluting. Disease can also be carried from plant to plant on hands. So, it is very important to disinfect your hands or gloves. Wash hands well, or you may want to carry into the garden with you some of the gel hand sanitizer that is now available.

In perennial beds, remove old flower heads, stalks, and any diseased plant parts. Examine roses for dead canes and remove them. Examine the shrubs and trees in your yard for dead branches or branches that are crossing and rubbing other branches. Prune these branches out. Pruning paint is not recommended to cover wounds made by pruning cuts.

If you planted annuals in the fall, such as impatiens, snapdragons, petunias, or geraniums, you may want to prune them back a bit and add some balanced slow release fertilizer. Gazania, Marguerite Daisy, Marigold, Nicotiana, Pentas, Salvias, Dianthus, and narrow-leaf Zinnia are some good annuals to plant in March for color through spring and into the summer. Gaillardia is a really drought tolerant flower that can be seeded directly into the ground near the end of March that will give you drought tolerant flowers all summer long. If you have shady areas where you want some color; Caladium bulbs have wonderful leaf colors.

When all of your clean up efforts are finished, put down a fresh layer of mulch. Be careful to keep the mulch a couple of inches away from the base of plants and not more than two to three inches deep. It is not necessary to remove old mulch beyond raking up diseased leaves and plant debris. Old mulch continues to decay, releasing organic matter and nutrients into the soil.

Once you have finished with your clean up – spruce-up activities, you are then ready to sit back, relax with a glass of iced tea and enjoy your handiwork – until those first weeds start showing up. A beautiful garden takes a lot of work, but I think the results are worth the effort!

Pruning Crape Myrtles

By Pam Brown
Urban Horticulture Extension Agent

Crape myrtle (Lagerstroemia indica) is a small tree that prefers hot, sunny climates. It is well adapted to our climate here in Pinellas County. Once well established, these trees are extremely drought tolerant and have low fertilizer requirements. Crapes grace us with lovely blooms in the summer. And, if pruned or trained properly, the bare trunk and branches are very sculptural after loosing leaves in early winter.

The common practice of chopping off the tops of crape myrtles is a severe pruning practice that induces excess vegetative growth, promotes sprouting at the base of the plant, creates unnatural branch structure, and results in larger but much fewer flowers. Many prune this way because the plant is too large for the space where it is planted or they see their neighbor’s trees pruned this way and feel that this must be the correct way to prune. There is also the misconception that this type of pruning is necessary to promote blooming. In actuality, light corrective pruning is all that is needed.

The best way to assure that the crape myrtle that you have planted will not grow too large for the space provided is to choose a cultivar for the mature size it will become. There are dwarf, semi-dwarf, intermediate and tree forms of crape myrtles. The University of Florida/IFAS publication Crape Myrtle in Florida (http://edis.ifas.ufl.edu/MG266) lists cultivars by name, size, color of blooms, and disease resistance.

Flowers are produced on new growth and crape myrtles will bloom without any pruning. Pruning can produce blooms of larger size, but there will usually be fewer of them. Removing seedpods as they form during the summer can stimulate another flush of blooms before fall. Full sun is required for best flowering. So, crape myrtles planted in shade will not develop many blooms.

Pruning should be done in January or early February before new growth starts. To allow the plant to develop into the small graceful tree that it is destined to become, select one to several strong trunks originating from the ground and prune off any weaker remaining stems at ground level. As the tree grows, remove lateral branches to one-third or halfway up the plant. Also remove any branches in the developing canopy that are crossing or rubbing another branch. This will develop an open canopy, which allows air circulation that will discourage fungal disease. Any broken or dead branches should also be removed. All cuts should be made either to the trunk or to a side branch that is facing out from the center of the tree. These are called thinning cuts that should not produce a heavy flush of dense growth in the canopy. In addition, the sprouts (suckers) that grow up from the base of the tree should be pulled out while they are still green a succulent.

There are lovely examples of properly pruned crape myrtles in several locations on the grounds of the Florida Botanical Gardens.