Fertilizer spikes not best way to feed trees

By Audrey Post
MS. GROW-IT-ALL

Q: Our sandy soil does not retain nutrients so we must fertilize. I found the use of loose, bagged fertilizer that must be spread by hand burns the grass and other nearby plants. We are now using Palm Fertilizer Spikes (6-0-6), which is slow release. After reading several articles that suggest that calcium is a necessary nutrient I discovered these spikes are lacking calcium. Does anyone make a slow-release fertilizer spike that is 15-5-15?

A: My first reaction was that if your lawn is being burned, you’re using too much fertilizer or you’re not applying it according to manufacturer’s instructions. I consulted David Marshall, the University of Florida/IFAS horticultural agent for Leon County, and he agreed.

“If the granular fertilizer is burning the grass, it is either being put out at too high a rate, or is not being watered in properly with a quarter-inch of water after application. Tree roots are widely spread beneath a tree and can run out into the lawn and other areas as far as three to four times the branch spread of the tree. For example, a small tree with branches that extend out 10 feet from the trunk may easily have roots running out 30 feet from the trunk,” he said.

“Therefore, spreading the proper rate of granular fertilizer over 900 square feet, or a 30- by 30-foot area, would do a much better job of distributing the fertilizer to the tree roots than merely putting in a few fertilizer spikes,” he recommended.

As far as adding calcium, you might not need to. Test your soil first. Contact your county Extension Office for a soil-test kit, which comes with instructions on collecting the sample and mailing it to the lab for testing. The cost is minimal, and it can save you a lot of money by telling you what nutrients your soil needs, and what it doesn’t need.

Gardeners in Leon County, Fla., can visit the Extension Office at 615 Paul Russell Road, about a mile east of the fairgrounds. If you garden in another Florida county, go to http://solutionsforyourlife.ufl.edu/map/index.html for a list of county Extension Offices around the state.

Gardeners outside Florida should contact their county's Cooperative Extension Service.

Internet Radio Show: Ms. Grow-It-All’s Internet radio show on the Free World Radio Network will not be broadcast this week. Join us next Thursday, July 30, 2009, at 6:30 p.m. for a discussion on rain gardens: http://www.blogtalkradio.com/Ms_Grow-It-All.

Skip 'Weed & Feed,' pull weeds from future beds

By Audrey Post
MS. GROW-IT-ALL

Q: I have an area along a sidewalk path that I want to turn into a flower garden. Right now, it is covered in different weeds. Can I spray "Weed and Feed" on those weeds and remove them from the area after they die? After that, I want to add some manufactured soil mix and plant my flowers and cover them with pine straw. Will the "Weed & Feed" be impossible to remove from the soil and kill whatever I plant in that area?

A: Whether you’ll be able to remove the “Weed and Feed” from the soil is really a secondary issue to whether the product will remove the weeds, thus allowing you to plant flowers in the area. Most “Weed and Feed” products are intended to feed the predominant plant in a given area while killing or preventing the growth of other plants.

In the case of grassy areas, “Weed and Feed” blends for lawns fertilize turf grass while inhibiting the growth of weeds and/or killing those that are present. Read the label to make sure you’re using a blend that feeds your specific kind of grass.

“Weed and Feed” formulas for flower beds fertilize the plants that are actively growing in the bed while inhibiting seed germination, generally preventing the growth of new weeds but also stopping any flower seed from germinating. It requires removing the weeds that are already growing before applying to be effective.

Using any kind of “Weed and Feed” concoction without removing existing weeds will simply feed the weeds that are there and prevent any seeds in the soil – whatever they are – from germinating. Since you want to convert a weedy area into a flower garden, this is not the right product for the job.

The best way to remove the weeds from your future flower bed is to dig them out by hand. You can use a chemical weed remover – not a “Weed and Feed” but a weed killer -- but you’ll have to wait until the residue has washed out of the area before you plant. The label on the weed remover will tell you how long you need to wait after application before you plant, but it sometimes takes multiple applications to kill existing weeds – especially if there are a lot of them. This could take a while, so you’ll save time and money as well as going “greener” if you dig out the weeds.

Once you have the weeds out, you can amend the soil with peat moss or compost to improve its structure and quality. I’m not sure what you mean by “manufactured soil mix,” but it doesn’t sound like anything you want to put into the ground. Save it for containers.

Overgrown camellia causing problems

By Audrey Post
MS. GROW-IT-ALL®

Q: We have a camellia at the corner of our house that is probably 15 or 20 feet tall, and it’s blocking our access to paint the house on that side. Can we cut it back?

A: This is an example of planting a tree or shrub without taking into account how big it can get. Your camellia is obviously too close to the house. If it’s preventing you from painting the side of the house, it might be holding in moisture and contributing to rot.

As painful as it is to let a mature camellia go, that’s exactly what you need to do. If you cut it back, eventually you or the next homeowner will have the same problem. You can cut it back, dig it up and move it if you’re really attached to it, or you can plant another one a more appropriate distance from the house. Remember: Any plant in the wrong place is a weed.

More on bottlebrushes: A couple of weeks ago, a reader wanted advice on how to tell whether her bottlebrush trees had survived winter freezes. David McManus, assistant director of grounds at The Florida State University, wrote to say that while common types of Callistemon are susceptible to cold damage, one seems to recover quickly. In addition, there’s a cold-tolerant one.

“I love bottlebrushes but unfortunately the local nurseries often carry Callistemon viminalis (large weeping) and Callistemon citrinus (fast-growing upright), which are more tender than Callistemon rigidus, which is a slower grower with narrower leaves,” said McManus, who earned a horticulture degree at the University of Florida. “Those two are frequently hurt by hard freezes, but viminalis has made fast recoveries in past years” at Tallahassee Community College.

Although the literature says C. rigidus is hardy only to Zone 9 -- Central Florida and points south -- McManus said it is dependable throughout Zone 8. “I have been growing rigidus at my family’s farm near High Springs since the early '80's and at my home near Havana since 2000 and I have not seen any injury from cold,” he wrote.

“Woodlander’s Hardy” is a cultivar that reportedly has high cold tolerance, he said, although he has never grown it.

Hummingbirds love Callistemon, so a cold-hardy variety is a treasure for gardeners wanting to attract hummers.

More on fertilizing dogwood trees: Last week’s column answered a reader’s specific question about the best time to apply fertilizer to dogwood trees. My answer might have left the impression that you must fertilize your dogwood trees, and that’s not true. If you want your trees to grow faster, apply fertilizer. But if you picked a good location that meets the trees’ needs and have good soil with adequate moisture, they’ll grow just fine without fertilizer. Many gardeners tend to overuse fertilizer, and the excess runs off and pollutes our springs, rivers and trees. If you use fertilizer, use a light hand.

Care and feeding of dogwoods

By Audrey Post
MS. GROW-IT-ALL®

Q: I use fertilizer spikes to feed my dogwood trees. Is now the right time to put out the spikes? Q: Can I plant a dogwood tree on my property at the coast?

A: Flowering dogwood, Cornus florida, is one of the heralds of spring, and you can see it starting to bloom throughout the Deep South right now. The flowers are inconspicuous clusters of yellow fuzz in the center of four bracts that make up what we think of as the dogwood blossom. White is the most common bract color, but there are cultivars with pink or red bracts. In fall, the leaves turn red or maroon, and the color is more vivid the farther north you go. The red berries are favored by birds and other wildlife.

It’s a popular tree for the home landscape, particularly as a patio shade tree, but it is susceptible to pests and disease, including dogwood anthracnose. The best way to prevent the disease is to keep the tree well-watered in times of drought and to avoid overhead watering.

Although it can take full sun, it really performs best with afternoon shade. Many people use it as an understory tree, but too much shade can make the tree grow too tall too fast, weakening the structure. Too much shade also reduces the number of flowers.

A dogwood can’t take salt, either in the air or in the water. It’s not a good choice for coastal property.

Dogwoods should be fertilized three times a year for the first three to five years after being planted, in March, May and August in Zones 8a and 8b, with a slow-release 12-4-8 or 15-5-15 formula. Calculate the area under the tree’s drip-line, the farthest point from the trunk where water drips off the leaves, and apply one-half pound for every 500 square feet of area. Spread the fertilizer a little beyond the drip-line.

Trees in Zones 7 and 6 need only two feedings a year, March or April and July. Once trees are established, they don’t need fertilizing if they’re growing where nearby lawn or shrubs are fertilized.

Different brands of fertilizer spikes have different strengths, so follow the directions that come with the package.