DIY Network

Growing Great Roses Is Easier Than You Think

Master gardener Joe Lamp'l, host of Fresh from the Garden, shares his expertise on cultivating roses.

advertisement

Although not new, neem continues to be a front-runner as an effective method of pest and disease control, especially with roses. Neem is derived from the neem tree native to India. (SHNS photo courtesy Joe Lamp'l)

Tips on growing great roses

By Joe Lamp'l

July 30, 2007 — As I tour gardens around the country, I'm often reminded that roses are one of the most feared plants to grow. Some gardeners try and succeed at growing pristine specimens, others attempt and give up, and some never try, waving the white flag before even getting started.

It's true; other than their beauty, roses are notorious for two things — their susceptibility to certain diseases, namely black spot, and as a favorite cuisines of Japanese beetles and other chewing, sucking pests. These thugs can decimate a rose bush practically overnight.

With diligence and proactive measures, pests and diseases can be kept in check. However, it's this extra attention, combined with the perceived need to wage chemical warfare that seems to turn away many gardeners, from those that try and give up to the ones that never even get started.

Great strides have been made in disease resistance when it comes to shrub roses. Rose breeder William Radler found it overwhelming to keep up with his own collection, so he began a mission of literally breeding the diseases right out of roses.

In 1988 his mission became a reality when the award-winning Knock Out Rose was created. Since its introduction, it continues to reinforce its reputation as a truly carefree, prolific blooming, disease-resistant plant.

Clearly there is an arsenal of products available to battle every pest and disease known to roses, but at what cost? I strongly advocate exercising increased levels of tolerance before reaching for a chemical control. Even then, I'll go for the most benign options first.

Through personal experience and interviews with experts across the country, I've made note of the most effective and environmentally responsible methods used at many of the top public and private gardens to keep their roses looking their best. This list includes some of my findings and offers more eco-friendly solutions.

Harpin Protein

This relatively new proprietary technology was discovered at Cornell University. It was called a "Major Scientific Breakthrough" by the USDA and awarded the Presidential Green Chemistry award by the EPA.

In nature, harpin proteins are produced by bacteria that cause plant diseases. Although harpin products have no direct effect on pathogens or pests, studies show that when plants detect harpin, they activate their own natural growth and defense systems to protect themselves. Harpin also activates the plants' photosynthetic activity making an overall healthier plant.

Harpin protein is sold as Messenger through Eden Bioscience Corporation (www.messenger.info). The powder is mixed with water and sprayed on plants periodically during their active growth cycle.

Neem Oil

Although not new, neem continues to be a front runner as an effective pest and disease control; especially with roses. Neem is derived from the Neem tree native to India.

For controlling and preventing diseases on roses such as black spot and powdery mildew, neem has many fans. As an insecticide, neem is effective at controlling one of rose's most notorious pests, the Japanese beetle. Neem can act as a repellent, disrupt the feeding cycle of certain other pests and can suffocate others.

Neem is available as a concentrate or as a ready-to-use spray. Be aware some neem RTU sprays include other active ingredients (organic or synthetic) to increase the killing power. I prefer the concentrate without the extras as a more eco-friendly route. It breaks down quickly in the environment and is non-toxic to mammals.

Potassium bicarbonate

Potassium bicarbonate has been proven effective in more than 200 university studies and nine years of organic agricultural use at preventing and curing many plant diseases including black spot on roses.

Unlike many other commercial fungicide products, potassium bicarbonate is even approved for use by the Organic Materials Review Institute (OMRI). It is currently available as GreenCure (www.greencure.net).

Of course, good air circulation, avoiding the use of overhead watering and proper sanitation help to ensure a healthy rose garden. But with effective, eco-friendly and timesaving options for keeping roses healthy, maybe it's time to think about taking another look at adding them to your garden.

(Joe Lamp'l, a master gardener, hosts DIY's Fresh from the Garden as well as a gardening radio show. For more information, visit www.joegardener.com. Distributed by Scripps Howard News Service.)

Get DIY On Your TV. Just follow the instructions to see if DIY Network is available through your cable or satellite provider.