Pruning now could make roses vulnerable to damage

By Audrey Post
MS. GROW-IT-ALL

Q: My Knockout roses really need to be pruned, and I know you said the best time to prune roses is in February but they really look shaggy now. Will I kill my Knockouts if I prune them now?

A: Maybe not, but you’ll certainly upset their normal growth rhythms and you could be putting them in jeopardy. If you prune them now, you’ll signal to them to get ready to start growing. That won’t be a problem if we have a mild fall and winter. But if your rose bushes are in full-fledged growth when a hard freeze hits, it will likely damage them and, depending on the severity of the freeze, could possibly kill them. That’s why we prune roses in February, so they can get a jump-start on growing after the freezing season.

They might look a little ragged now, but you’ll really be better off if you wait until February to do any hard pruning. This isn’t like pruning azaleas, which are evergreen. A late season pruning likely will remove any buds for next year’s azalea flowers but it won’t jeopardize the plant itself. It’s designed to live through frosts and freezes in our area. Pruning a rose too late in the season could do nothing or it could kill it. It all depends on the weather.

Q: I planted a small wildflower meadow but it didn’t produce many flowers. Should I reseed it for next year?

A: Yes, I would sow a few more seeds in your meadow this fall. So many things affect the germination rate of wildflower seed – the availability of water, heat, the age of the seeds – and it takes several years to establish a wildflower meadow. Scatter a few more seeds to increase the odds of germination and flower production. Once established, the flowers will re-seed each year.

Make sure you’re using a mix of wildflower seeds blended specifically for the Southeast for the greatest chance of success.

Internet Radio Show: Ms. Grow-It-All’s Internet radio show now broadcasts live at 6 p.m. Wednesdays at http://www.blogtalkradio.com/Ms_Grow-It-All. Just cut and paste the link into your browser window. If you can’t join us live, you can download a podcast from my Web site. This week’s topic was preparing your lawn for winter. Next Wednesday, our topic will be planting a garden for wildlife.

Don't fertilize Knock Out® roses until spring

By Audrey Post MS. GROW-IT-ALL®

Q: We have 11 Knock Out® rose bushes, which my husband feeds two-thirds of a cup of 6-6-6 Blooming Rose Fertilizer monthly. They have grown to about 4 feet high and bloomed beautifully over the spring and summer. Should we keep applying rose food throughout the fall and winter months? Also, should Knock Out® roses be pruned? If so, when should we prune them and how much?

A: Knock Out® roses have become among the most popular shrubs in the home landscape, thanks to their ease of care and prolific flowering. They’re disease-resistant, drought-tolerant and self-cleaning – meaning no dead-heading of spent blooms. They’ll bloom from spring until the first hard-freeze.

I would lay off the fertilizer through the fall and winter months. You might get a few blossoms here and there as our temperatures do their normal fluctuations, but you don’t want to keep the plants in high gear for growing and blooming over the winter. New growth is more susceptible to freeze damage, and consequent damage to the entire plant might result.

If you have room to let them continue to grow larger and they’re holding a good shape, leave the pruning shears alone. If you want to keep them to a smaller size and shape, prune them in early spring – which for North Florida is February. It’s a matter of personal choice and space. One friend said hers grew to a 6-foot tangled mess the year she didn’t prune them; another never prunes hers and they stay about 4 feet tall and wide. Soil and climate differences can play a big role.

If you choose to prune your Knock Out® roses, cut the shrub back to about 12 inches. As it grows throughout the season, use hand-held pruners to snip off wayward branches that are outpacing the others to maintain the shape.

Q: When Tropical Storm Fay blew through in late August, most of my sloped back yard was under water for a few days. The St. Augustine grass at the top of the slope, closest to the house, seems to have recovered but the grass farther down where it is shadier is still looking sad. What should I do?

A: From your description, it sounds as though the grass at the bottom of the slope was under water longer, so it makes sense it would take longer to recover. Lack of oxygen can drown plants as well as people.

The fact the area is shady is probably slowing down the drying-out process. Make sure there’s no mulch helping to hold in moisture right now – you want to give the water a chance to evaporate – and wait and see. Anything else you do right now would probably interfere with your grass’ ability to recover on its own. Grass slows its growth this time of year, so not seeing new growth doesn’t mean it’s dead.

If the barren appearance bothers you, spread some ryegrass seed over the area once it’s no longer soggy. If it sprouts, you’ll know the area is drying out and your St. Augustine likely will reappear next spring. If not, you’ll have to decide whether to re-sod, plant something else or create a mulched area.

Remove oleander caterpillars while young

By Audrey Post
MS. GROW-IT-ALL®

Q: Big hairy worms have been giving me fits for the past seven years, eating the leaves on my mandevillas. I use the white powder and maybe it cuts the population, but I hate the way it makes my plants look. What else can I use that will kill the worms but not kill the plant? I am attaching a photo so you can see what a charmer this is.

A: Yes, indeed, that is one charming pest you have there. It’s a Syntomeida epilais, commonly known as an oleander caterpillar. Supposedly it feeds only on oleanders, but it obviously has developed a taste for mandevillas – as your photo illustrates. Through a little research I learned that its original host was a pineland vine that is now rare, so it has been known to try new foods.

A mature oleander caterpillar is orange with tufts of black hair and is about 2 inches long. The adult moths are purplish-black with white dots on their wings and are sometimes called polka-dot wasps. They reproduce three generations a year, and sometimes the process overlaps and you can see larvae and moths at the same time. They’re really rather exotic looking, but they can be devastating. While they usually don’t kill the plant, they can defoliate it and leave it vulnerable to diseases that can kill it.

This is one caterpillar that birds and small mammals have learned to avoid because its primary diet, oleander, is so toxic. There are beneficial insects that will eat oleander caterpillars -- predatory stinkbugs, parasitic flies and wasps, even imported red fire ants eat the clusters of eggs – but the best way to control them is to pick them off by hand. The spines generally pose no threat to humans. [Ms Grow-It-All® update: A subsequent column, post date Dec. 17, 2008, discussed one person's allergic reaction to the oleander caterpillar, so use gloves to pick them off just to be safe.]

The egg clusters can be found on the undersides of leaves, and you can scrape them off into a plastic bag – a newspaper bag works well for this – and throw them in the trash. Young larvae, which are more yellow than orange, eat the tissue between the veins on the leaves. Snip off the infested leaves, but them in a plastic bag and then place the bag in the freezer for 24 hours to kill the caterpillars. Larger larvae can be picked off, placed in a plastic bag and frozen the same way, or dropped into a can of soapy water.

Obviously, it’s hard to pick larvae from large oleanders because of the height, but a mandevilla vine should be easier to manage. Horticulturists recommend your friendly white powder, Bacillus thuringiensis, for large plants.

The key appears to be catching them while they’re young.

Q: What should I do to try to save a hanging spider plant that was left outside when we had frost? The leaves have turned black and slimy.

A: Those cold nights sometimes sneak up on us, and different microclimates in our yards and gardens sometimes get colder or warmer than the “official” temperature recorded. It could have been 37 at the airport but 32 on your porch.

If it wasn’t too cold for too long, the plant might survive. Cut off all the slimy, damaged foliage and clean up any debris on the soil surface. You can bring it inside, give it some water and see if it starts to grow again, or you can skip the water, move it to a protected location such as an unheated shed and let it rest until spring.

However, unless it’s a variegated variety or a sentimental favorite, I’d pitch it and start over next spring with something else. Solid green spider plants have become invasive in the ground here in North Florida, and those airborne babies can make that leap from the hanging basket to the ground very easily.

Mechanical help needed to remove big azaleas

By Audrey Post
MS. GROW-IT-ALL®

Q: We bought property near Lake Talquin a couple of years ago, and the former owners had planted azaleas everywhere – and I mean everywhere. There’s no pattern to it, and unfortunately, no lawn. We need to get rid of some of them. What’s the best way? Will Roundup work? They’re about 20 years old and we tried digging one out and it took hours.

A: This is a great example of a bit of ancient gardening wisdom: Any plant in the wrong place is a weed. Some weeds are easier to remove than others, and as you’ve seen, this isn’t one that you can simply tug and it will spring free.

Roundup® and other chemical sprays are designed to be absorbed through the foliage and move through the plant, eventually killing the root. They work fine on soft-stemmed weeds, but they are not the most efficient way to kill shrubs. It would take repeated applications over a long period of time, which would cost a lot of money and likely leave the area so toxic that grass wouldn’t grow. Even products designed to kill woody shrubs take a while, and a 20-year-old azalea in good health could probably withstand a couple of applications. It wouldn’t look good, which would just add to your problems, but it would survive. And you’d still have to dig it out.

The easiest way to get azaleas out is with heavy equipment, such as a backhoe, which can scoop out the bush and its roots in one bite. If that’s not an option, either because of the cost or because of the potential damage to other landscaping, you’re going to have to dig them out by hand.

Before you start hauling azaleas out of there, do a little prep work to make sure you’re removing the right ones. It sounds like you want to end up with a lawn and have the remaining azaleas create a pleasant pattern, Try to visualize what a spot will look like without each azalea that you want gone. One technique is to take a digital photo, then edit out the shrubbery. A low-tech version is to get photo prints and cut out the azaleas you think you want to remove, then lay the photos on paper and color in grass or dirt where the azaleas were. If you like the way it looks, great. If not, it’s easier to print a new photo than re-grow a 20-year-old shrub.

Prune the azaleas to 18 inches to 2 feet high. Rake back all the mulch and cut every surface root you see with a shovel. Then dig about 2 feet down and 2 feet out all the way around, using a pickax or mattock to cut larger roots. The shrub may start to give a little when you pull on it, but it still has a taproot holding it in. You’ll have to dig out around the tap root to be able to cut it.

Yes, it’s a lot of work. If you have a heavy truck or tractor, you can hook a chain around the base of the azalea and pull it out, but it’s much easier if you prune it and cut the side roots first. Also, you can water the azalea to soften the soil before you pull it out, but makes sure you keep the water on the azalea and not on the ground where the truck will be. Otherwise, you’ll end up with ruts in your yard or even worse, your truck mired up to the axles.

Select the right fruit tree for your climate

By Audrey Post
MS. GROW-IT-ALL

Q: I would like to add fruit trees – apples, pears, etc. -- in my yard, and I was told back in the spring that I should wait until fall to plant them. Now that it’s fall, what varieties should I plant?

A: Fall is indeed the best time to plant trees here in North Florida. With our mild winters and the growing list of hybrids developed for our climate, it’s possible to grow fruit trees historically limited to more northern climes.

Although fruit trees require a lot of maintenance to keep them producing – mainly annual pruning and vigilance in checking for pests and diseases – they do make lovely additions to the home landscape. But don’t expect to grow fruit that looks or tastes like the specimens in the grocery store. Homegrown fruits here tend to be smaller but have a better flavor.

The key is to plant the right low-chill variety for the climate. A certain number of hours below 45 degrees – chilling hours – are needed to produce fruit. The varieties that produce in North Florida have been bred to produce on fewer chilling hours than varieties that grow up north. Most of North Florida gets between 540 and 700 chilling hours, with the western Panhandle tending to get more hours than the Big Bend.

The two most common apples grown here are Anna and Ein Shemer, both Israeli hybrids introduced into the Florida market in the late 1960s.Anna, a red blush, is more tart than Ein Shemer, which is yellow and sweet. Dorsett Golden, which legend says is the result of a Mrs. Dorsett tossing away the seeds of a Golden Delicious apple at her home in the Bahamas, and the seeds taking root and producing a fruiting tree, also is popular here. TropicSweet, a hybrid bred from Anna, is a newer release that offers blush fruit that is sweet.

All four produce tasty fruit that are smaller than the apples you find in the grocery store, most of which have been commercially grown up north. Most apple trees don’t self-pollinate, so plant two varieties that bloom at the same time. Traditionally, gardeners have planted Anna with Dorsett Golden because they bloom at the same time. Dorsett Golden will also pollinate TropicSweet.

If you want to plant pears, Flordahome and Florida Bosc produce soft pears suitable for eating fresh. The variety called Pineapple produces hard pears, the kind more suitable for preserves and chutneys.

Most local nurseries have knowledgeable employees who will help you choose the right tree for your yard. Use caution when buying fruit trees at big-box stores, which often buy in bulk and sell the same tree in Tallahassee that they sell in Toledo. If that tree does survive here, it won’t bear fruit. Know your cultivars before you shop.

Make sure your newly planted trees get enough water the first year, at least 3 or 4 inches per week, and fertilize in January and again in June.

Prepare tender plants for freezing weather

By Audrey Post
MS. GROW-IT-ALL

Q: After waiting too long last year to bring my porch plants inside the house, and consequently losing some of them, I am determined to do it right this year. But I’ve read that bringing them back inside too abruptly can be harmful, too. Plus, I’m worried about bringing bugs in the house. What’s the best way to achieve an orderly transfer back indoors?

A: Many potted plants, such as African violets and tropicals including orchids and bromeliads, are tender – meaning they’re sensitive to cold – and should be protected from temperatures below 40 degrees. It doesn't need to get down to freezing to damage them. Other houseplants, such as philodendrons and spider plants, can take a little cold but not a hard freeze.

What's the difference between a frost and a hard freeze? A couple of pre-dawn hours at 30 to 32 degrees is a frost, and most plants that aren’t “tender” get over it. But if it gets down to 28 for a couple of hours or more, your plants will feel it.

Moving plants into a heated home on a chilly night, especially if they've had a progression of nights outside where the temperature has gradually dropped, could cause a shock to their systems and seriously damage them.

So what to do to prepare for our North Florida version of winter? If you’re planning to move plants indoors, first move them to a shaded, protected spot for the next week or so. By protected, I mean out of the wind and rain. If a frost comes in the next couple of weeks, you’ll more than likely be able to cover the plants there instead of taking them indoors.

What you do after that depends on how much work you’re willing to do. You can move the plants from the shady, protected spot in your yard to your house a garage, unheated basement or garden shed after a couple of weeks, cut back on the water and monitor them through the cooler months.

Or you can move them inside the house. The process of moving them in stages is sort of the reverse of taking seedlings out during the warmth of the day in early spring, then bringing them back in at night.

If you’re worried about bugs, give the plants a strong blast from the garden hose. Check the leaves, undersides as well as tops, and pick off any remaining pests. If you want something a little more reassuring, you can mix a mild solution of insecticidal soap and spray it on – a 99-cent spray bottle from the discount store works well – and move the plants inside.

But unless your plants are really tender, you might want to consider leaving them outdoors in a protected location. It will enable you to cover them easily when freezing weather threatens, or move them to the garage, shed or basement if the forecast is really severe.

Wait until crinum's foliage dies to prune it

By Audrey Post
MS. GROW-IT-ALL

Q: My crinum lilies are looking a little ratty. Most have finished blooming. Can I cut the browning foliage back or will it hurt the plant’s performance next year?

A: It’s the time of year when lots of summer-blooming perennials start to look a little rough. While it’s OK to cut back some spent plants, you should leave your crinum lilies alone. As long as foliage still has some green, photosynthesis is still happening and the plant is storing food for the winter and for next year. If you cut off those less-than-perfect strappy leaves, the size and bloom could be affected next year. Just like daffodils, you want to let crinums die back naturally.

If the foliage has turned completely brown and crumbles when you touch it, it’s finished. Go ahead and pull it out. You won’t even need to cut it.

If your plant isn’t quite to that stage yet and its appearance really disturbs you, set a big pot in front of it full of fall mums. Or you could divert the eye with a stunning display of fall color in another part of the yard. Area nurseries are full of fall bloomers and end-of-season summer perennials.

Q: I have a very large grapefruit tree, at least 10 feet tall, that until two years ago was kept in a pot. It has lots of thorny branches. Is this typical of grapefruit? I have a Satsuma tree that will get some thorny limbs and my neighbor told me to cut them off. The Satsuma has finally begun to bear after five years. The grapefruit has not flowered or set fruit. I live in Killearn Acres and the tree is in full sun with afternoon shade. It faces east. Should I cut off the thorny branches? How old do grapefruit trees have to be to set fruit?

A: Some citrus trees have thorns, some don’t. Many of the more modern hybrids have been bred not to have thorns, but I’ve never known of thorns to make any difference in whether a citrus tree bears. Two of my citrus trees have thorns; the rest don’t. They all bear.

Do you know what variety your grapefruit tree is? Some are slower to bear, and your tree might not be ready yet, especially since it was in a pot a long time. It could be putting its energy into getting its roots established.

I know of a grapefruit tree in Killearn that is loaded right now with ripening fruit, but it’s at least 30 feet tall and has been there for years.

I suggest you get the soil around the tree tested to see whether it’s deficient in any major or minor elements, and fertilize next February.

Footnote on Leyland cypress canker: After reading last week's column on Leyland cypress canker, Stan Rosenthal, Leon County's extension agent for forestry, noted that foliage blight can present similar symptoms to canker. "The difference has more to do with the pattern of the browning of the foliage," he said, "but both can be avoided by not over-planting any one variety."