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Cabbage Worms

We are first-time gardeners and have planted Brussels sprouts and green and red cabbage that we are trying to grow organically. There are black egg sacs and small green worms eating the leaves. Is there an organic product we can use on the cabbage?

Egg sacs can be washed off with a hose.

There are several organic methods you can use to deter cabbage worms. Lightweight polypropylene row covers, placed over a row of plants and supported by hoops, will block wind and insects while permitting light, air and rain to reach the plants. Hold down the row covers with soil, stones or bricks.

Another organic method uses pots of mint growing between cabbage plants. The mint odor is said to deter cabbage moths. Don’t let the mint take root, however; it will take over your garden. Rotenone dust is considered organic, as it leaves no poisonous residue on plants. The use of hot pepper spray is an irritant to insects and worms, but also to your skin and eyes. Bacillus thuringiensis (Bt) is a specific biological control that is fatal to cabbage worms if ingested. Note that it can be harmful to certain butterfly larvae.


Perennial Pinchback

Is there an overall rule about when to pinch back my leggy plants?

“The reason plants are pinched back is to obtain compact and bushier growth. This is generally done three times during a growing season, or you can apply the 6 nodes rule,” says Jennifer Brennan, horticulturist, Chalet Nursery, Wilmette.

After 6 weeks of growth, trim back half of the growth, or wait until you see 6 nodes on the plant stem to trim back to get more branching. For plants that respond, such as chrysanthemums, use the 6 node criterion.


Raising Lawn Level

I want to raise the level of my lawn as much as 2 feet in places. I now have a large quantity of somewhat composted wood chips and I am wondering if I can use them as fill to raise the ground level and provide a good soil in which to sow a lawn.

“It is not a good idea to use only wood chips to raise the grade of an area,” says Greg Stack, University of Illinois extension educator, horticulture. While wood chips may raise the grade for a while, over time they will decompose and eventually the site will sink. Even using them as fill and putting soil over them is not a good idea.

“I would not use straight compost by itself to raise the lawn level, but mix it with soil,” adds Stack.


Plumeria

I brought a frangipani (Plumeria) back from Hawaii last April when it was just a leafless branch. It sprouted leaves and grew over summer. Now it is losing its leaves. How can I keep it growing over winter? Will it bloom?

During winter, plumerias defoliate naturally. Keep your plant somewhat dry.

” We keep it in the cactus section over winter because it really likes to dry out. It doesn’t need a lot of misting. A southwest window with bright light is the best exposure for it.” says Lourdes Espinosa, greenhouse associate, Sid’s Nursery and Greenhouse in Palos Heights.

In spring, depending on the weather, and as the days lengthen, resume watering and fertilize with a high-phosphorus liquid fertilizer every two weeks. When the night temperatures remain reliably above 50 degrees, the plumeria can be grown outside. Acclimate the plant slowly to the outdoor light by keeping it in a shady place for a week. It flowers from summer to autumn.

Plumerias can grow into a 3-foot shrub with good care. Wear gloves when pruning since the sap is toxic and irritating to the skin.


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.


Overwintering Marginal Plants

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.

“Pushing a plant past the limits of its hardiness is not for the average gardener,” says Marie Dvorak of The Planter’s Palette in Winfield, “but plants can sometimes be successfully overwintered by siting them in a special microclimate such as a sheltered southern exposure.” Another tip comes from horticulturist Ann Hancock at Michigan State University, where they are trialing perennials that the English firm Blooms of Bressingham is introducing in the U.S. Hancock explains that the best way to keep perennials that are tender in Zone 5 or that are rated for Zone 6 is to grow them in raised beds with good drainage because poorly drained wet soils will cause the roots to rot. In addition, it is important to check perennial beds for plants that have heaved out of the soil through repeated freezing and thawing. Replace them in the soil and protect with mulch.

One example of a marginally hardy plant that will be getting attention this year is ‘Flamenco’, a new cultivar of Tritoma (Kniphofia, red-hot poker) that has just been named an All-America Selections Winner for 1999. Tritomas should have their foliage tied upright so water does not remain in the crown, said Hancock.


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.


Tomatoes

After my father’s tomatoes ripen on the vine, he finds when he cuts into them that there is a hard white core that extends through the fruit.

“This is a common problem,” says Dan Woldhuis, owner, Woldhuis Farms, Grant Park. “Customers bring their tomatoes to me with hard cores.”

Sometimes this is the result of weather that’s too hot and then suddenly cold.

But more likely it is the variety. Change to a soft-skin, less firm tomato such as ‘Celebrity’ to overcome the white core problem. I’ve grown this for many years and sold it at the farmers’ market, but it is too soft for the commercial market and is best for home growers.


Cucumbers

The foliage on our cucumber plants is starting to wither and turn yellow. They get plenty of water and I feed them regularly. What could be wrong?

“The plants may be getting too much water. They can tolerate fairly dry soil,” says Tim Norris, owner Spring Bluff Nursery, Sugar Grove. There are other possible causes for yellowing foliage as well. The cucumber beetle may have fed on the plants when they were small and transmitted bacterial wilt, which later plugs the vascular tissue. To prevent the beetle from feeding on young plants, use row covers until the plants get larger. A stressed plant is also open to attack by bacterial wilt.


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questions

I applied commercial compost and hardwood mulch to an area where I am establishing a small garden. I did a few soil tests on the area and the results indicated the nitrogen was depleted. I intend to spread a bag of dried blood to rectify this problem When is the best time to apply the dried blood?

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

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