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Coneflowers

I thought that purple coneflowers were insect proof, but now I see some aphids at the bud and tiny flies. What is wrong?

Purple coneflower (Echinacea purpurea) is a common native perennial that grows best in sandy or well-draining soil and full sun. If you are not giving your plant these growing conditions, certain insects can attack your plants.

Aphids are sometimes visible on buds, and as sucking insects they cause stunted and deformed leaves. Spider mites are tiny insects that often multiply in hot, dry conditions. Spider mites feed on sap and cause yellowish leaves. Thrips are barely visible, tiny insects causing bud malformation.


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.


Sowing Seeds

I would like to start seeds under lights. When is the best time to start flower seeds? The seed packet always says to sow a number of weeks before the last frost. When is the last frost?

“In this area we use May 15 as a benchmark for the last frost date, but it can be earlier or later,” says Chuck Prosek, grower at Prosek’s Greenhouse, Winfield.

If your seed packet gives you the number of days to germination, add that to the number of weeks for growth, and then count the number of weeks back from May 15. Tomatoes sown indoors generally need 6-8 weeks of growth before being set out.

Many seed packets do not include germination time. A good guess is to allow 1-2 weeks for the seeds to germinate, but if you use bottom heat, your seeds will germinate earlier and grow faster. Most seeds need warm soil of 65 to 70 degrees to germinate and grow.

When you sow seeds directly into the soil, till the upper inch of soil to loosen it for direct seed to soil contact. The outside soil temperature must be above 50 degrees for cool growing plants, and at least 65 degrees for warm season annuals, according to Prosek.

For future reference, keep a record of indoor sowing dates, germination dates, length of indoor growing period, and transplanting dates.


Cycas

I have a cycas palm and am not sure how much direct sunlight or water it needs. It has light brown marks developing on the leaves. What is causing this, and how do I care for my plant?

Cycas palms or sago palms (Cycas revoluta) are tough house or patio plants. They are neither palms nor ferns but primitive cone-bearing relatives of conifers. A rosette of green feather-like leaves, 2 to 3 feet in height, grows from a central point at the top of a single trunk.

Cycas need bright light and should be kept relatively moist with weekly watering. However, prolonged rainy spells can cause fungal leaf spot disease.

“The shiny brown spots are probably caused by scale,” says Jeff Frohn, sales associate at Geimer Greenhouses, Long Grove. “It can be treated with fish oil, vegetable oil or an all-in-one insecticide spray,” adds Mike Geimer, owner, Geimer Greenhouses.


Hibiscus

I am growing my potted tropical hibiscus indoors for the winter. The leaves are starting to yellow and fall off. Should I give the plant iron and should I fertilize it? Do I cut it back, and if so, when?

Hibiscus leaves turn yellow in response to the change in environment. The older leaves fall off first. If the leaves are chronically pale yellow with green veins, the plant could be lacking iron, but in your case, it is probably the change in growing conditions that is affecting the plant. When the days get longer in February or March, prune it to shape it, or cut it down to force good bottom growth.”

“Don’t panic; the plant expresses itself dramatically,” reassures Mike Geimer, owner of Geimer Greenhouses, Long Grove. “Don’t be timid pruning it.”


Asparagus

Can I grow asparagus from seed? I saved the little red berries from my plants.

You can grow asparagus from seed. I have done so many times, but it takes three or more years for a crop, and growing from seed usually gives inferior plants. Better crops come from hybrid plants.

If the red berries from the female plant have dried over winter, there should be two or three black seeds inside. Clean them off and prepare your seed bed for planting.

Asparagus needs full sun and a sandy loam soil raked smooth. After the danger of frost is past, bury the seeds at a depth two times its diameter and keep the bed moist. In the third year you can lightly cut the pencil-thin stalks. There are often volunteers of female plants between rows you that can transplant. However, it is best to start asparagus by buying roots so you have a small crop the first year. Most varieties sold are male.


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.


Japanese Maple

I’m moving to a townhouse with limited direct sunlight. I would like to put a Japanese maple in a north-facing garden but don’t know if it will do well. What are the best kinds? Also, when is the best time to plant a small tree?

Japanese maples are small decorative trees which are becoming more popular as more dependable cultivars come on the market. Even so, an established tree will sometimes succumb in a severe winter. Their light requirements vary.

The trees can grow in a northeast exposure, and 6 hours of sunlight is not too much, according to Jeff Sibley, nursery manager of Red’s Garden Center, Northbrook. They need a moist, well drained, neutral soil, amended with organic matter. They can grow to 8 feet tall in a good location. He says the best planting time is right after Mother’s Day. A protected spot and plenty of moisture are critical elements for survival, even with the newer cultivars.

Sibley recommended the following cultivars of Acer palmatum var. dissectum, a cut-leaf variety, as the most graceful trees:

  • ‘Crimson Queen’ is a small shrubby tree, with finely cut reddish leaves that hold color all summer and turn scarlet before dropping off in the fall.‘Garnet’ is similar to ‘Crimson Queen’ but a somewhat more vigorous grower.‘Bloodgood’ is a vigorous, upright tree with blackish red bark. It has deep red spring and summer foliage, scarlet in the fall.
  • Acer palmatum var. dissectum ‘Viridis’ Lace Leaf Japanese Maple is a small shrub with drooping branches, green bark and pale green, finely divided leaves that turn gold in autumn. It takes shade.

Compost Bin

I’d like to start composting. Do you have any advice on what kind of bin to purchase/build so that it is successful in the Chicago climate?

Compost, decayed organic matter, improves soil structure, porosity and density and creates a better root system. It increases moisture retention and nutrients while adding significant quantities of organic matter to the soil. It is such a valuable addition to garden soil that it is worth the effort to collect and store waste vegetative material until it decomposes.

Compost bins range from low to high tech. A compost heap can be as simple as a pile of leaves stored at the rear of your garden. The most costly composter is a revolving two-tumbler device with a rotator drum that separates new material from finished material and discharges the final product.

Ideally, if you are saving a mix of unshredded plant material that includes flower stems, large leaves and small branches, a three-bin system works best. Stake out three 36-inch square cages using fence rails, lattice or steel wire. Raw material goes into the first bin. When it is partially decomposed, aerate it and shift it to the second bin, and put the most highly decomposed matter into the final bin. With that method, you can keep adding fresh material as the season progresses.

Do not put any diseased plants in the pile. Keep it in a concave shape to hold rainwater, and aerate it occasionally. As the pile “cooks,” it will heat up during the summer. An interior temperature of 180 degrees will kill bacteria but is not often attainable; 120 degrees is more likely for a mix of green and dried leaves.


Pumpkins

I’d like to know the secret to growing a decent-sized pumpkin for jack-o-lanterns for the grandkids and for decorating. My experience in recent years is that they get about as big as a basketball and then begin to rot. What am I doing wrong?

The longer the fruit is on the vine, the greater the chance it will rot. By September its size is apparent, and it turns orange. It is best to plant pumpkins in different soil each year or every two years, according to Sue Murdock, manager, Goebbert’s Pumpkin Farm, South Barrington.

The size and use of pumpkins is determined by the seed you buy. ‘Atlantic Giant’ produces fruits that weigh hundreds of pounds. A better choice is to grow ‘Howden’. It bears well-shaped 10 to 20-pound fruits, the perfect size for jack-o-lanterns. ‘New England Pie’ is the standard for pies with smooth, bright orange flesh. ‘Wee-B-Little’ is a miniature round pumpkin bearing 3- to 4-inch fruit useful for table decorations and suitable for tiny hands.


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questions

We have a skylight in the bathroom over our Jacuzzi tub with an area around the tub that is quite large. What plants can we grow there, and what care do they need? Can we grow orchids?

I’d like to start composting. Do you have any advice on what kind of bin to purchase/build so that it is successful in the Chicago climate?

Can I grow asparagus from seed? I saved the little red berries from my plants.

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