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Mandevilla

I brought my mandevilla plant into the house to overwinter. How best can I keep it? Will it flower? Can I root pieces of it?

Mandevilla is a tropical vine requiring high light. Keep it in the sunniest part of your home. It will not flower over winter because the light intensities will not be great enough to bring on flowers and many of the leaves will fall off. It is best to keep it in a semi-dormant stage by trimming it back, withholding fertilizer and allowing it to dry out between waterings. Mandevilla is prone to aphids, white fly and mealy bugs, but don’t treat the plant preventively with an insecticide. It doesn’t work, and it also adds unnecessary chemicals to your indoor air. Treat a bug problem only if one develops. One preventive measure that does work is to give your houseplants a periodic shower or spritz them with a hand spray in the kitchen sink.

When the days are longer in early spring, begin feeding it with a 20-20-20 plant food to encourage new growth and then switch to a 20-30-20 formula. “It’s hard to propagate in winter, but in spring when your plant gets a burst of new growth, you can try to root cuttings,Ôø‡Ôø‡Ôø‡ advised Susan Izenstark, tropical specialist at Jamaican Gardens, Morton Grove.


Staking Plants

I dislike staking perennials. Is there anything I can do to avoid it?

There are several techniques you can use to limit time spent on this chore, but it is difficult to totally

avoid staking some plants.

First and foremost, the old adage “right plant, right place” means full sun perennials need to be grown in full sun for tight upright growth. If they are too shaded, the plant will stretch or bend toward the sun and grow in a loose habit. Growing plants a little closer together also helps because it enables plants to support each other.

The best remedy to avoid staking is to cut some tall plants down by one-half in June. That will delay flowering in helenium, monarda, platycodon, chrysanthemum and aster, but the plants will remain upright. If you really want to eliminate cutting back, grow dwarf versions of these plants.”
Short, thin branches from forsythia or dogwood (known as “pea staking” in England) can be placed around the perimeter of newly emerging plants to help keep the stems upright. Some garden centers have begun selling bundles of branches for this purpose. In a short time, the shrub cuttings are covered by emerging shoots. This technique works well with fine foliage such as baby’s breath or flax.

There are numerous staking supports from bamboo to iron rebar rods. Wire staking supports are available in full, half and even quarter circles to support single stems. Peony hoops can be left in place over winter and will support not only peonies but boltonia, baptisia, and even errant tomatoes.

Some plants always need to be staked. Giant dahlia tubers need a heavy stake dug into the hole at planting time. That prized, single-stemmed iris, lily, or delphinium can get blasted in a storm, and then it’s too late to save it.

Remember: the time to stake plants is during the cooler days of spring when plants are growing rapidly and not on humid July days. Staking should be done unobtrusively and subtly for plants to retain their natural grace.


Miniature Gardening

Miniature gardening is the rage. What enchanting miniature plants work well in a shaded area?

T Biernacki
Many miniature plants grow in shade. Some unusual ones are the 6-inch tall Solomon’s seal (Polygonatum humile ‘Tom Thumb’), the 2-inch tall Ajuga reptans ‘Planet Zork’ and two cultivars of the very slow-growing conifer Cryptomeria japonica: ‘Koshyi’ and ‘Tenjan’. Or look for two European gingers, Asarum forlesii ‘Mercury’ and Asarum takaoi ‘Roundabout’, which are about 3 inches tall. Also: the maidenhair fern (Adiantum venustum), mosses and miniature hostas

M Samios
The best and most obvious answer is miniature and small hostas. From the ever-expanding “mouse” series with ‘Holy Mouse Ears’, ‘Mighty Mouse’ and ‘Giantland Sunny Mouse’ to newbies such as ‘Mini Skirt’, ‘Ladybug’, ‘Baby Booties’ and ‘Little Starlet’… perfection! Add some grass-like carex such as ‘Beatlemania’ for texture, miniature Solomon’s seal (Polygonatum humile) and dwarf heucheras from the Little Cute series, and your garden fairies will be in heaven.

C Bornmann
If you’re planting in the ground, these low-growing perennials will add interest and texture to your garden: Irish and Scotch moss (Sagina sublata and S. subulata ‘Aurea’ – best in part shade), brass buttons (Leptinella squalida) and miniature hostas. Add color with annuals such as polka dot plants (Hypoestes), ‘Strawberry Drop’ coleus and torenia. It’s important to add perennials and annuals into your garden for a longer season of color.


Trumpet Vine

Will a trumpet vine growing on a tree harm it?

Trumpet vine (Campsis radicans) is a vigorous vine which can climb to the top of a tree in one season and spreads by suckering roots. It blooms in full sun in clusters of 3-inch-long orange tubes with flaring scarlet lobes.

The vine will not harm an established tree but a young tree could be stressed.

“There may be root competition between the vine and the tree for moisture, especially if your tree needs a lot of water. However, trumpet vines can grow with less moisture. When customers claim their vine does not bloom, it is because they are watering and pampering it too much,” says Lori Harms, greenhouse manager, Countryside Nursery and Garden Center, Crystal Lake.


Purple Coneflower

I have read that purple coneflowers (Echinacea) are a good source of food for birds in the winter. Will they be okay if not trimmed back until spring? If so, how early should they be trimmed?

If your coneflowers remain standing over winter, the seed heads will be available as bird food and will also be an attractive presence in the winter garden. They should be cut back in early spring before April. If you prefer, you can cut the plant back after frost and throw the seed heads on the ground.


Rose Rosette Disease (RRD)

What is rose rosette disease? I lost two antique roses and removed a hedge of multiflora roses that were supposed to be undesirable. How bad is it?

Rose rosette disease is a plant killer of unknown origin and no known cure. It is known to plant pathologists, but unknown to most rose gardeners in this area.

The disease is believed to be caused by a virus or virus-like pathogen that has been spreading through much of the wild rose population in the Midwest, probably transmitted by a mite introduced to the U. S. to eradicate multiflora roses. It is lethal to the wild multiflora rose and potentially lethal to many rose species and cultivars.

Symptoms of rose rosette disease are highly variable, depending on the species or cultivar. Some of the more recognizable symptoms include rapid elongation of new shoots forming witches brooms, or clustering of small branches with distorted leaves of conspicuous red pigmentation and distorted flowers.

David Robson, Springfield, extension educator, horticulture with the University of Illinois, reports that it is all over our area. Mike Geimer, owner of Geimer Greenhouse, Long Grove, reports coming across RRD in a Long Grove garden. One plant in a bed of Flower Carpet roses caught his eye because of its uncharacteristic red clumping stems. He looked up the symptoms on the internet, identified it as RRD and advised immediate removal of the plant. Also important, warns Geimer: “Always sterilize pruning shears.”

Kathy Hallgren, Sycamore, is worried about the future of old roses. Two summers ago she noticed some peculiarly rampant irregular, hyper-thorny pink growth with irregular leaves on an antique Alba rose.

After researching the symptoms, Hallgren determined the irregularities were from RRD. “I dug out the plant and burned it. Once I learned that multiflora roses could be the culprit, I removed them even though they were healthy. This summer I saw it on one of my ‘William Baffin’ roses so cut it down and burned it. This disease means business,” says Hallgren.

No effective control is available for existing rose rosette disease. All cultivated roses are potentially susceptible. Be on the lookout for it. Early detection is the key to effective cultural control. If the disease is recognized early and the rose is removed, it is possible to save other roses in the garden and hopefully curb the spread of RRD.


Orchids

What causes black spots on my orchid leaves?

There are a number of causes for black spots, depending on the type of orchid.

“In some varieties, like Oncidium ‘Cherry Baby’, the small black spots through the leaf are normal,” says Liese Butler, owner, Oak Hill
Gardens, Dundee.

Black spots on the top of the leaf could be sunburn, caused when sunlight scalds a drop of water that has been left on a leaf. Newer growth of Cattleya orchids can normally have a purplish spot. A black mushy spot and a black stem indicate rot.


Dwarf Junipers

Why do I have brown areas near the tips of my dwarf Japanese junipers? This has been occurring the last few years. They are supposed to be drought resistant”

“It’s hard to diagnose without seeing the plants or their location,” says Matt Warrick, sales associate in tree and shrubs at Gethsemane Garden Center, Chicago. “Your plants may be in a situation that’s too dry. With the type of drought we had this past summer, even if a plant is drought-tolerant, it would have needed supplemental watering.”

Other factors that affect junipers are poor drainage, insufficient light, fungal disease, and insufficient acidity in the soil. Any of these conditions could cause needle browning.


Colorful Shrubs

I am interested in improving fall color in my yard. What shrubs turns red beside burning bush (Euonymus alatus)?

Wendy Vichitk, plant manager at Luurs Garden and Flower Shop, Hillside, recommends these shrubs for a colorful fall garden:

Low growing 2- to 3-foot Virginia sweetspire ‘Little Henry’ (Itea virginica) has red foliage and grows in both sun and shade. The foliage of the somewhat taller ‘Henry’s Garnet’ is dark red, as the name indicates.

Fothergilla ‘Mount Airy’ has blue-green leaves that turn intense yellow and orange-red in sun and half shade.

Oak leaf hydrangea (Hydrangea quercifolia) grows in shade or partial sun, with orange-red to red fall color.
The leaves of apple serviceberry (Amelanchier grandiflora) burn a bright orange red. There are several cultivars on the market to choose from.

Many viburnums have bright fall color. The easy to grow Korean spice viburnum (Viburnum carlesii) and the also fragrant V. juddii have leaves that produce a mixture of red, orange and mahogany. Arrowood viburnum (V. dentatum) and cranberry bush viburnum (V. trilobum) both exhibit typical red-purple color.

The intensity of color is affected by the weather. Warm sunny days followed by cool nights bring the highest leaf color. The health of the plant, its growing conditions, and the amount of water the plant receives also affect fall color.


Types of Fruit Trees

I am going to be planting five dwarf fruit trees; two ‘Bartlett’ pears, one ‘Cresthaven’ peach, and two ‘Honeycrisp’ apples. Could you give me some feedback on them?

If you buy young container fruit trees, plant them very early in the spring to lessen transplanting shock (as soon as the soil can be worked and before the buds break). Plant the tree at the level it was in the pot, adding a layer of top mulch.

“Wrap the trunk in paper or plastic tree wrap to prevent deer and rabbit damage. Protect the trunk from voles with fine wire mesh at the base,” says Tim Norris, president of Spring Bluff nursery, Sugar Grove.

‘Bartlett’ pear is subject to fire blight and also needs a pollinator for good fruit production. ‘Patten’ and ‘Parker’ are two pear cultivars Norris recommends. Two different cultivars will give you better cross-pollination.

‘Honeycrisp’ apples are an excellent choice for this area. They grow up to 20 feet tall on semi-dwarf root stock. They can be pollinated by any member of the Malus family, including a nearby flowering crab tree.

‘Cresthaven’ peach, while hardy here, may not bear fruit, depending on how cold the winters are. When the temperature goes down to zero, ‘Cresthaven’ peach loses all its flower buds. Norris suggests growing ‘Reliance’ peach instead. It needs a long growing season. Last spring (2008) was a cool one and peaches did not bear much fruit. Peaches are not long-lived trees. By the time the tree is bearing fruit, you will need to start growing another tree.


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questions

I keep seeing photos of interesting plants I’d like to grow, but they’re labeled zone 6 and I’m in zone 5. What can I do to successfully overwinter these marginal plants? I’d like to try them, but I don’t want to waste my money.

How do I contact customer service?

I have a hoya houseplant that has been growing happily for eight years. It had flowers when I received it, but it hasn’t bloomed since. What am I doing wrong? Can I get it to flower?

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