Spider mites like it hot. Watch your roses

QUESTION: What could be stripping the leaves off the branches of my roses? I spray with a product that is supposed to protect roses from insects and diseases, but it hasn’t helped.

Keep an eye on roses when it’s hot and dry. Spider mites can turn a lovely rosebush into an ugly mess.

This time of year, with this kind of weather, suspect spider mites, which thrive when the weather is hot and dry, say rosarians at the Nashville Rose Society. The tiny creatures get on the undersides of leaves and feed on the plant’s juices. The damaged leaves look speckled, turn yellow and fall off.

Spider mites are not insects; they are more closely related to spiders, so insecticides won’t have any effect. You can use a miticide, but it can be expensive. The best and cheapest way to control them is with a blast of water directed at the undersides of the leaves, rosarians say. If you do this every three days for a week or so, you break the mites’ gestation cycle.

Here’s a little more information about the tiny arachnids: Adult mites are less than 1/50 inch long. They use their mouthparts to pierce individual plant cells and remove the liquid. They produce webs that can coat the foliage with a fine silk that collects dust, making the leaves look dirty.

You can’t see them, but you can certainly see the damage. Heavily infested plants will be discolored, and if they are not controlled, the rose can be stunted, or even killed.

Record heat is trouble for trees

Meteorologist Bobby Boyd sends me email from time to time about extreme weather conditions. The latest concerns the large dome of high pressure building eastward out of the plains and across the Tennessee Valley that has put Middle Tennessee, as he says, “in the pressure cooker.” We’re breaking records this weekend. No rain in sight, and gardens are suffering.

Young trees and shrubs are especially vulnerable. The Nashville Tree Foundation has sent an alert with watering guidelines and new tips that you can read here to help trees survive.

Keep these tips handy. It’s still only June, and we’ve got a long way to go.

Coming up in July

July 14:  Middle Tennessee Iris Society rhizome sale, 8 a.m. – 3 p.m. at Ellington Agricultural Center. All types of irises available in a variety of colors, priced from $1 – $6. A great chance to add to your collection! To learn more: For additional information see our web site www.middletnirisociety.org.

July 17: Middle Tennessee Orchid Society meets at 7 p.m at Cheekwood. On the agenda: an orchid auction and discussion on Cattleya Orchids. To learn more, visit www.tnorchid.com.

July 17: Perennial Plant Society meets at Cheekwood in Botanic Hall. Refreshments and plant swap at6:30; meeting and program at 7. Guest is Kelly Norris, horticulturist, plant breeder and manager of Rainbow Iris Farm inBedford,Iowa will present “The Modern Plant Explorer.” The meeting is open to the public.

July 26: Farmer Jason performs at Family Night Out at Cheekwood, 6:30 p.m. The event is free with regular Cheekwood admission. www.cheekwood.org.

July garden calendar

Does this heat make you wish for a shade garden? Find tips on plants that have it made in the shade, plus things to keep you busy in the garden in July, in Saturday’s Landscape & Garden calendar in The Tennessean.

Tomatoes out of control

QUESTION: I grow tomatoes every year, and in the past I have used cages – first the round ones commonly available at the big box stores, and later some of the square type. Even with the square ones the plants always overcome the cage. They get leggy and end up coming out of the cages on the sides and then bend over the wires. This year I tried staking the plants and did not use cages, but I encounter the same issues, the side growth spreads out and I have to tie them every which way. What am I doing wrong? — Wayne

Tomato plants quickly overwhelm flimsy wire cages.

Those flimsy wire cages – the round ones – must be some kind of joke. Anyone who grows tomatoes knows that they don’t do much to support a full-size plant. Even if the vine doesn’t grow out over the top, the weight of a bumper crop of ‘Better Boys’ will topple those supports. The square cages are a little better, but they still won’t contain all those wayward limbs.

If you want to use cages, the best bet is to build your own, using sturdy wire fencing (or some suggest panels of concrete mesh, which has openings large enough to reach your hand through). Using the cage in addition to a tall, sturdy stake should keep the tomatoes standing upright and within bounds a little better.

Still, if the tomatoes are indeterminate varieties – that is, they continue to form tomatoes throughout the growing season — it helps to do a little pruning. As the plant grows, it will develop “suckers” in the angles between the main stem and the side stems. You should pinch or snap or cut these suckers off to keep the plant from getting too bushy. As the tomato plant grows taller, tie the main stem loosely to the stake.

By the way, it’s best to install stakes and cages at planting time. It’s surprising how quickly a tomato plant can grow out of control. Keep that in mind for next year.

Events

June 2: Seeds of Hope self-guided garden tour. Six gardens in Belle Meade, Green Hills and Oak Hill, 9 a.m. – 3 p.m. Tickets $25; proceeds benefit Monroe Harding programs for children. www.monroeharding.org.

June 3: The Nashville African Violet Club meets at 1:45 at the Green Hill Women’s Center, 10905 Lebanon Road in Mt. Juliet. E-mail Julie.mavity@gmail.com to learn more.

June 9: The Robertson County Master Gardeners are hosting a garden tour of some of the most beautiful gardens in theSpringfield area. Visitors will see garden ponds, a greenhouse, garden sculptures, and woodland settings and some unique plants in these private gardens. Hours are10 a.m. – 2 p.m.; tickets are $5 per person, $8 per couple and will be available on the day of the tour on the pavilion of the UT Extension Office on the square inSpringfield, and at the Potting Shed in Greenbrier.

June 9: Plan a road trip to Rugby, Tenn., for an all-day event at Historic Rugby Cumberland Plateau Gardens. The day begins at 9 a.m. (Eastern Daylight Time) with “Rugby Landscape Gardening From 1880 to 2012” by Rick Murphy, followed by  “Garden Design Sun to Shade” a workshop by Bob Washburn of Wolf River Valley Growers. Lunch, garden tours and a British Cream Tea round out the schedule. The cost is $40, and advance reservations are required. Proceeds benefit Historic Rugby. Information, 888-214-3400.

June 10: The Tennessee Gesneriad Society meets in Cheekwood’s Botanic Hall at2 p.m. Program is a Mini Show. Contact Julie at 615-364-8459 to learn more.

June 15 – 16: The American Hosta Society is convening in Nashville this year, and the public is invited to visited the National Hosta Show at the Nashville Airport Marriott Friday, June 15,2  – 5:30 p.m., and Saturday June 16,9 a.m. –noon. Vendor areas will be open during those times, as well. This is expected to be one of the largest hosta shows in recent history with more than 800 entries expected. Visitors to the show will have the opportunity to see a wide range of sizes and colors of hostas, displayed as single leaves, hostas not yet on the market, hostas grown in containers, and hostas used in artistic designs. Read more about the convention here.