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Notes from a seminar present by Marilynn Mitchener at Goodwood Gardens.  Information was obtained courtesy of American Rose Society.

Feedback recently received by the Canadian Rose Society from a garden centre in eastern Canada:  

My customers are interested in information on how to grow roses, new varieties, disease resistance, and the use of roses in their landscapes. In short, they are looking to be educated about growing roses.

  How to Grow Roses

    Rose Requirements

    Planting 

    Planting Bare Root Roses

    Planting Potted Roses

    Planting Miniature Roses

Fertilizing

Mulching

Pruning

Deadheading

Winterizing

What about bugs?

Disease Resistance

Common Diseases

Disease Resistant Roses

Reading about Roses

     Rose Requirements  

1.              Roses prefer a minimum of 6 hours of sun each day. The less sunshine that a rose receives, the less it will bloom. In fact, it could even die. Some roses are more shade tolerant than others, but we’re talking ‘dappled’ shade not deep shade. Gruss An Aachen (Floribunda), Iceberg (FL), Zephirine Drouhin (Bourbon), Souvenir du Docteur Jamain (HP) and Madame Plantier are more tolerant to shade.

2.          Roses require good drainage. Clay soil is not their favorite soil. Sand is not good either. Roses do not like wet feet. Friable soil with plenty of compost, leaf mold, coffee grounds, banana skins, egg shells, grass, pine needles is best. Test your soil when planting. If water does not drain through – amend the soil. PH level should be 6.0-6.5 (slightly acidic).

3.             Water roses deeply once a week using a drip hose. Depending on the size of the rose bed(s), get yourself a couple of hoses. Lay them down where you need them and leave them. Turn on the water and leave it running for an hour or so. If the weather is hot or/and dry, water twice. It’s okay to use a regular hose – you can water roses overhead.

4.           Water early enough in the day so that  all leaves are dry before nightfall. 

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Planting

        Plant roses away from trees or large shrubs – at the drip line so roots do not compete.

Plant the bud union (graft) a minimum of 2 inches below soil level. If you are in a colder zone (farther north or west), plant the roses deeper.

        Dig the hole approx 2 x 2 feet and deep enough to ensure that the graft is at the required depth for your area. Place the rose in the hole, spread the roots out and put the shovel handle across the hole to check the depth of the graft.  If the hole is deep enough, sprinkle compost, bone meal around the rose roots and half fill the hole with soil. DO NOT FERTILIZE. Water with a bucket full of water and allow the water to drain through. Complete filling the hole with soil and water again with one bucket of water.

Bare root

        Place the rose in a mud bath–water and soil from the bed where the rose will be planted–for a minimum of two hours. More is better, but not more than 24 hours. If you can’t plant them right away, either leave them in their packaging or dig them in temporarily.

Add rooting hormone, bone meal to the ‘bath’.  Don’t fertilize. Wait for two weeks before any fertilization program is started.

Potted Roses

        Dig the hole before cutting the sides of the fiber container. Don’t leave the fibre pot on the rose. It retains water. If the rose is in a plastic pot, water the rose well before removing the rose from the container. Follow the planting directions above.

Miniature Roses

If the rose is on its own roots, you should plant it one inch deeper than it is in its pot or container.

Miniature roses can be grafted just like the larger varieties. If the mini rose is grafted onto rootstock, plant the bud union at least two inches below the soil surface—just as you would for all grafted roses.

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Fertilizing

        Two weeks after planting, start your fertilization program. What fertilizer are you going to use?

        For good rose production, you need a high middle number. New rose fertilizers have increased the first number (nitrogen). You can use granular, water-soluble powdered fertilizer but don’t use only chemical fertilizers as this damages the soil by increasing the salt content. Many roses will flourish only with a solid diet of organic fertilizers including animal waste (pony poop), blood meal, shredded leaves, sea weed, fish emulsion! provides a balanced diet with mineral nutrients. Organic fertilizers help make the micro flora and ‘fauna’ ready for action. In mid-May and early July, sprinkle 1/3-1/2 cup of epsom salts around the base of each rose. This induces new cane growth (basal breaks). When using chemical inorganic fertilizers always saturate the soils well with water before and after use.

        As soon as the ground is dry enough in spring and roses have been pruned, start fertilizing. To get the season going, roses need a ‘blast’ of nitrogen to wake them up. In addition, lay on a combination of compost, pony poop or other manure and water in. Use ‘teas’ including alfalfa or manure teas as well.

        How often should you fertilize? If using water soluble fertilizer (Plant Prod), every 10 days to 2 weeks and after each rain. Water- soluble fertilizer drains through with the rain…. So this is another reason why it’s so important to use natural methods as well.

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MULCHING!

        Once you’ve planted, pruned and fertilized – mulch the roses. Mulches to use include grass clippings, shredded cedar mulch.  Shredded pine will draw out the nitrogen from the soil and leaves at the base of the plant may start to turn yellow. Add additional nitrogen fertilizer if you use this type of mulch. Mulch should be 2 inches or more deep. The more the better as this will help the soil retain moisture and aid in disease reduction by smothering blackspot and other fungi.

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Pruning

        Pruning should always be done in the spring after the Forsythia have started to bloom. In the fall, limited pruning should be done to keep the rose from “rocking” (canes whip-ping in the wind will cause the roots to be shifted/lifted).  The amount of pruning you do depends on whether you want to show roses in a competition or simply display them in the garden as well as on the type of rose.  Cuts should be made at a 45º angle approx ¼” from a bud eye. A bud eye is where a new branch will grow.

·         Remove all dead, crisscrossed, diseased, or dying canes.

·         Remove all thin, weak canes that are smaller than a pencil in diameter

·         A budeye lies near every point where a leaf is attached to a cane. Other than basal breaks emerging directly from the bud union, budeyes are the only points from which a new cane will grow. Pruning canes just above a budeye will encourage new growth to start more swiftly.  

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Deadheading

    Deadheading is the removal of spent blooms. It’s a form of pruning. To remove faded blooms, make your cut just above the second set of 5 leaves. Just below the bloom is a set of three leaves. Below this first set of leaves are sets of 5 leaves. The goal is to cut the stem far enough down the cane so that when the new growth emerges, you'll have a decent-sized cane. If you cut up at a 3-leaf set, the new cane emerging will be quite small. Removal of the dying blooms causes the plant to generate new blooms. Stop deadheading in the fall to ensures that the rose will go into dormancy and will not create new growth to be killed by the first frost.

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Winterizing

All good things come to an end. There are a few ways to winterize your plants depending on such factors as:

·         The zone you live in

·         The depth you planted the roses

·        Your own comfort level – and time and effort you want to put into it.

If you are unsure of the rootstock but you wisely planted the graft/bud union well below soil level, you may choose to:

·         Take a chance and leave them as is-- allow fallen leaves to cover the bed.

·         Mound up soil around the base of the rose canes.

·         Trim the rose so that it fits under a rose cone. Place a brick over the cone to hold the cone in place for the winter or use tent pegs to secure the cone to the ground. 

·       Use a circular plastic mesh frame and fill the frame with soil and leaves.

·       Cover the whole bed with a cage and cover the frame with special polyfoam and clear plastic.

·       Spray Wiltpruf on the rose canes.

·       Spray dormant oil on the roses before the temperature drops below 50F or 10C.    

·       Or a combination of any or all of the above.

Considerations: cover the fallen leaves with compost and well-rotted manure. It will act as a mini compost pile and feed the plant during the winter.

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What about bugs?

The major ‘bugs’ that pester roses include the following:

Aphids – wash off with a strong spurt of water or ‘squish’ between fingers. Ladybugs are the best solution. In order to have ladybugs in your garden you can’t use insecticides and you need to leave decomposing plant material in your garden over winter.

Rose Midge – mosquito-like, 1-2 mm undetectable to the eye. Buds turn black as if burnt. Overwinter in the ground in cocoons and emerge as adults in the spring. This is the time to use chemicals – granular diazinon while it is still available. Sprinkle on the ground or spray the ground with liquid diazinon every 10 days.

Rose Slugs or Saw Flies – look like caterpillars but they are not, consequently some insecticides such as Bacillus thuringiensis (e.g., Safers BTK) will not kill them. The young larva begins feeding as a skeletonizer on the underside of the leaves and as it matures it chews large holes on the leaves and rose buds. Use a contact or systemic insecticide. Safers Insecticidal soap. Safers BTK will kill leaf rollers and tent caterpillars.

Spider Mites – rarely seen on outdoor roses if you water overhead. Overhead watering will eliminate this pest. Mites can be rusty green, greenish amber or yellow and they have eight legs. They extract the sap and the tissue of the leaf collapses in the area of the puncture. Soon a spot without green color forms at each feeding site. After a heavy attack, an entire plant may become yellowed, bronzed or killed completely. An alternative to chemical controls is a strong water spray applied to the undersides of the leaves every three days during hot weather.

Thrips - Adult thrips have strange, feather-like wings that carry them from flower to flower where they feed on both pollen and plant sap. Spreads other important diseases; the most important of which is tomato spotted wilt virus. The thrips family does have one redeeming member, the Six-Spotted Thrips, a cannibal of the thrips world that will feed on their fellow Western Flower Thrips as well as two-spotted spider mites. These good guys are easily identified by the six distinct black spots, three on each wing. to reduce thrips populations is to remove spent blooms from the plant promptly and to destroy them along with the thrips inside.

Earwigs - The plant damage is done by their chewing mouth parts, not by their ominous pinchers found at the tail end of earwigs.

Organically minded gardeners have been using newspapers to trap earwigs during the night, then placing the newspaper into tightly sealed garbage cans in the sun to die a horrible death. Earwigs can be drowned in soapy water or beer, depending on your fancy. You can also use ½ inch of vegetable oil in a tuna or catfood tin as a trap. 

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Disease Resistance

A good deal of effort has been made in recent years to develop roses with greater disease resistance. How are you going to find out which ones have this trait?

1. Check rose gardens at Royal Botanical Gardens www.rbg.ca or the Niagara Parks Botanical Gardens  www.niagaraparks.com

2. Ask a rosarian.

3. Join a rose society--

4. Check web sites. Some web sites have more information than others.

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Common Diseases

Blackspot – yellow areas form around blackspots and the plan becomes defoliated. This is a fungal disease spread by water splashing off the ground. Spray leaves with Funginex, remove diseased leaves.

Downy Mildew – looks a lot like Blackspot.  This is also a fungal disease,  purplish dark spots on leaves. Leaves fall. Usually occurs in moist, humid conditions.

Powdery Mildew – white to gray fuzzy growth on buds and leaves. Water will kill the disease. Make sure leaves are allowed to dry during the day. Leaves become distorted, buds fail to open. Occurs when the day and overnight temperature difference is greater than 10ºC.

Rust – orange pustules on the lower side of leaves and on canes. Usually the first sign is tiny orange spots that appear on the upper side of the leaves. Fungal disease. Very virulent and will kill the rose. Spores are airborne and favour cool, moist weather. Remove all portions of the plant that are infected (leaves, canes). Spray with sulphur, CIL Fruit tree spray. 

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Disease Resistant Roses

Carried by Goodwood Gardens (Spring 2004)

Goodwood carries an excellent selection of disease-resistant, hardy roses for Ontario gardeners.

Blanc double de Coubert  

Bonica

Dublin Bay (excellent climber)

Flower Carpet varieties

Folklore (excellent Hybrid Tea)

Friesia (aka Sunsprite) (fragrant too!)

Gene Boerner (almost thornless)

Golden Wings

Gold Medal

Henry Hudson

Iceberg

J.S. Armstrong

Jens Munk

John Cabot

John Davis

John Franklin

Knockout

L.D. Braithwaite

Lambert Closse

Little Darling

Love and Peace

Maria Stern

Meidiland roses

Morden Blush

New Zealand

Nicole

Pascali

Showbiz

Singing in the Rain

Sexy Rexy

Sunblest (HT, aka Landora)

The Fairy

The World Rose

Warm Wishes

Winchester Cathedral

William Baffin

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Reading about Roses? Watch out!

·         You don’t have to spray insecticides every week (Flyer #6 from Landscape Ontario).

·         HGTV.ca included an article “All About Roses” in February 2004. It contained lots of misleading, incorrect information for Canadian gardeners. For example, it told gardeners to plant the base (they meant bud union) of the rose 2 inches above the ground.

·       Magazines from the US will carry U.S. information. Many articles are written for the southern U.S. (zone 7 and wamer).

·       The American Rose Society includes an extensive section on ‘All about roses” as well as links to numerous horticultural extension services and universities. Many articles are designed with regional requirements in mind.

      Damage from Rose Midge

    Rose slug

    Blackspot

    Downy Mildew

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Copyright © 2002 Goodwood Gardens
Last modified: May 09, 2007