Washington State University Extension

Garden Tips

Archive for March 2012


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Imagine your BLT (bacon, lettuce, and tomato sandwich) with a purple slice of tomato instead of a red one. It just could happen if you grow ‘Indigo Rose,’ a new tomato bred at Oregon State University. Jim Myers, a professor in the OSU horticulture department, notes that Indigo Rose is the ‘first improved tomato variety in the world that has anthocyanins in its fruit.’

Tomato fanciers know that there are already a number of purple and ‘black’ tomatoes, most of them heirloom varieties, with green flesh and a muddy purple to brown skins. Indigo Rose is different because it has a beautiful true dark purple skin and red flesh.

Why did Myers and OSU work hard to develop a ‘really’ purple tomato? Why spend time, money, and effort coming up with an interesting novelty tomato for home gardeners? Having an intriguing novelty variety for gardeners was not their goal. They were aiming at breeding tomatoes with high levels of antioxidants. Anthocyanins, the purple pigments found in many fruits and veggies, are antioxidants that are believed to have significant health benefits. With tomatoes as one of the top veggies that people eat, imagine the benefit of making it more nutritious by making it purple.

Coming up with a true purple skinned tomato wasn’t easy. The work started in the 1960s when an American and a Bulgarian scientist crossed cultivated tomatoes with wild ones from Chile and the Galapagos Island. Imagine Myers’ patience as year after year he grew the most promising lines, evaluated them, and then kept on crossing and selecting lines until he finally came up with Indigo Rose, fondly called ‘Rose’ for short.

A pretty purple tomato is a novelty but gardeners won’t keep growing it if it doesn’t taste good. Myers notes that it has ‘a good balance of sugars and acids and tastes just like a tomato’ should.
It’s a full season tomato that ripens about 91 days after transplanting, making it about a week later than Early Girl.

Many gardeners are concerned about GMOs, varieties that have been created using genetic engineering. They can grow Indigo Rose without fear, because it was bred using natural plant breeding methods. In addition, it’s open pollinated and seed saved from the fruit will produce plants and fruit true to the parents.

The one to two ounce salad-sized fruit are produced on compact indeterminate vines . They develop their bright purple color before they mature, turning more of a dull purple-brown when ripe. However, not all of the skin will be purple. Those areas of skin not directly exposed to sunlight will turn from green to red as the fruit ripens, including the bottoms of the fruit. Like any tomato, Indigo Rose tastes best when allowed to fully ripen on the vine.

Myers indicates that his next step is to come up with purple cherry tomatoes. He hopes to have one available within the next three years. Imagine a fresh summer salad filled with colorful little red, gold, and purple tomatoes! By the way, you won’t get a purple tomato sauce made from Indigo Rose fruit because the anthocyanins leach out of the skin when cooked.

Chances are you won’t be able to find transplants of Indigo Rose at a local garden store, so you’ll have to grow your own. Seed may be purchased from Territorial Seeds Company in Oregon (, Nichols Garden Nursery in Oregon (, Johnny’s Selected Seed in Maine (, and High Mowing Organic Seeds in Vermont (
Published: 3/23/2012 11:55 AM


>written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Which is better, Wave petunias or Supertunias? It’s almost like the shoot out at the O.K. Corral, the dueling lines of vigorous hybrid petunias available to gardeners. Neither line of petunias resembles the wimpy petunias of the past that typically faded away as soon as scorching hot summer weather arrived. Both Wave petunias and Supertunias are heat tolerant, blooming all summer long even during hot weather. Both grow best in full sun with evenly moist, well-drained fertile soil. Neither requires deadheading to keep them blooming. Both are vigorous growers that produce oodles of flowers, outperforming the petunias of yesteryear.

Both Wave petunias and Supertunias need a steady supply of nitrogen as they grow. This may be supplied with slow-release fertilizer added to the soil or potting mix before planting or by regular feeding with water soluble or light applications of granular fertilizer.

Developed in Japan by the Ball Horticultural Company, the Wave series of petunias were the first vigorous, heat tolerant hybrid petunias to arrive on garden store shelves over 15 years ago. Low growing and spreading, they were initially developed to be a groundcover type petunia. Propagated from seed, they generally have a sizeable root system.

The Waves are great for use as groundcover type bedding plants or in containers. However, most cultivars are extremely vigorous and can overwhelm and crowd out other plants in container gardens. Because they’re so vigorous, they can become a little leggy in late summer. If they do, cutting them back in early August will renew their appearance for the remainder of the season.

There are now about 55 different cultivars and five main types of Wave petunias. The classic Waves are five to seven inches tall and three to four feet in width. The Easy Waves form one foot tall and three feet wide mounds of color. The Tidal Waves with big flowers reach a height of two feet and a width of five feet and make excellent groundcovers. The Shock Waves are newer additions to the Wave line with smaller flowers and more restrained growth. They’re better suited for smaller spaces. The Double Waves have double flowers and work well as ‘spillers’ in containers and hanging baskets.

Marketed by Proven Winners, the Supertunias are newer arrivals at the garden store. There are about 30 Supertunia cultivars, most growing from six to ten inches tall and trailing to two to three feet in length. The Supertunia Vistas have a mounding, cascading growth habit, growing to two feet both in height and width.

The Supertunias are sterile and are propagated vegetatively from cuttings. They’re not as excessively vigorous as the Waves and work well in hanging baskets or mixed with other plants in containers. They’re less likely to overtake and crowd out other plants.

My favorite Wave is probably one of the originals, Wave Purple Classic. I also like the more restrained Shock Wave Pink Vein (light pink with dark pink-purple veins) and Shock Wave Denim (multi shades of denim blue-purple). Amongst the Supertunias, I especially like the SupertuniaVista Bubblegum (bright pink bubble gum), Supertunia Citrus (bright pastel yellow), and Supertunia Raspberry Blast (striped bright and lighter raspberry pink). One very unique Supertunia is Pretty Much Picasso with violet purple flowers edged with lime green.

So when it comes to a showdown between the Waves and the Supertunias, I can’t decide which is better. It’s up to you to decide who’s the winner for your garden. Look for both types at your local garden store this spring.
Published: 3/16/2012 11:49 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Last week we talked about when and how to prune roses. Since spring is right around the corner, now’s a good time to talk about the two rose problems that local gardeners often face… aphids and powdery mildew.

APHIDS: Aphids are small green or pinkish soft-bodied insects found in clusters on succulent new bud and stem growth. The aphids suck sap from the plant. When they’re present in high numbers, they damage growth. Rose aphids overwinter as eggs on buds and stems, emerging at the same time that new growth begins in the spring.

Horticultural oils can be used to help minimize aphids problems by smothering aphids eggs before the young aphids emerge. The oils are applied at the delayed dormant stage, when the buds start to emerge.

There are other least-toxic ways to discourage the buildup of aphid infestations on roses. Avoid excessive or unnecessary applications of nitrogen fertilizer. The nitrogen promotes vigorous, succulent growth where aphids like to feed. Using a slow-release or low nitrogen fertilizer can avoid lush early-season growth.

Another non-chemical option for managing aphids is water. A strong stream of water can be used to wash aphids off rose leaves and stems. Spraying roses regularly with water is an easy way to keep aphid populations down.

If these methods fail, there are a number of organic and inorganic pesticides for aphid control. The easiest to use are the systemic insecticide products that are mixed with water and applied to the soil for uptake by the roots. The Bayer Advanced product line includes several soil-drench products containing imidacloprid for use on roses.

POWDERY MILDEW: Powdery mildew is a fungus disease characterized by a white powdery coating on leaves and buds. You can minimize powdery problems by not encouraging succulent growth which is most vulnerable to infection by powdery mildew. Also, sprinkling plant leaves with water helps by washing spores off the plant.

One new ‘organic’ spray that gardeners have been reading about for control of powdery mildew is milk, yes the stuff that comes from a cow. However, while this recommendation has appeared in various gardening publications, Linda Chalker-Scott, WSU Extension Horticulturist, points out that there have been no published scientific studies investigating the use of milk to prevent powdery mildew on roses or other ornamental plants. There have been studies on the effectiveness of milk spray applications for the control of powdery mildew on melons, cucumbers, and squash. These studies indicate that whole milk does provide some control of powdery mildew.

Chalker-Scott notes that the only anecdotal evidence, not scientific research, indicates that milk is effective in controlling powdery mildew on roses. She also points out the drawbacks of using milk for powdery mildew prevention include the unpleasant odor of the milk fat as it breaks down, the growth of benign fungal organisms that colonize the leaves as part of the break down process, and that milk may only be effective if it’s applied prior to powdery mildew developing.

With those drawbacks, you may prefer to use an organic or inorganic fungicide for control of powdery mildew on roses Most of these require frequent (every seven to ten days) application to protect new growth as it develops. However, tebuconazol can be applied as a soil-drench for uptake by the roots. Several Bayer Advanced rose care products contain both tebuconazol and imidacloprid, providing aphid and powdery mildew control for ‘up to six’ weeks. These products are a bit pricey, but they avoid the risk of spray drift and don’t require spray equipment or frequent re-application.
Published: 3/9/2012 11:33 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

It seems like almost every area gardener grows roses if they have the space. Gardeners who are particularly fond of roses seldom have just one shrub, more often it’s ten, twenty or more. Perhaps this overwhelming affection for roses is why gardeners ask so many questions about roses, including when to prune, how to prune, and how to manage rose pests and diseases.

The most common inquiry is regarding the best time to prune roses in the spring. Local Tri-City rose experts and experts from around the country recommend waiting to prune until the yellow-flowering shrub forsythia is in full bloom. For impatient gardeners it’s hard to wait this long, especially when the leaf buds are swelling and appear ready to pop open. Waiting helps protect the plant from frost and cold damage that can still happen during late winter and early spring.

Roses tend to be very forgiving shrubs, so you can pretty much prune them any time of the year without killing them. However, pruning at the ‘wrong’ times of year can weaken the plants. Avoid pruning them right after they leaf out in the spring. Roses should also not be pruned in late summer or early fall because it can stimulate new growth that wouldn’t be ready for winter, making the plant more vulnerable to damage from cold winter temperatures.

What can be done about overgrown roses shrubs that haven’t been pruned for a year or more? Get rid of them? There’s no need to yank them out, but the tangled mess will be difficult to approach with just pruning shears and light-duty loppers. Brenda Viney of the Vancouver Rose Society (Canada) notes that the Royal National Rose Society in England recommends an ‘easy care method’ of pruning for modern shrub roses.

This ‘easy care method’ involves using a small chainsaw, hedge trimmer, or pruners to simply cut rose shrubs back to half their height in the spring, ignoring any fine pruning to remove weak and twiggy canes. She points out that the Royal National Rose Society indicates that these ‘roses flourish just as well as those pruned in the traditional method.’

I know of some local gardeners who use a chainsaw to cut back their roses in the spring and then they do a little cleanup pruning to open up the center of the shrub and remove old woody canes and any weak, spindly growth. Using a small chainsaw or heavy-duty hedge trimmer might be the easiest way to cut back neglected roses and regain control. I would recommend pruning them back to about 10 to 18 inches in height and then pruning to open up their centers.

Published: 3/2/2012 11:25 AM



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