August and September have been wetter than normal this year, causing many people to complain of the persistence of powdery mildew. Because of this wetter condition, Black spot has been a problem, as well. It would be wonderful if one of these summers we did not have any of these diseases. I doubt that that will ever happen here in the Northwest because of our low night temperatures. Now that this rose season is coming to an end we need to begin our Fall and Winter rose care.
If you need to move your roses before winter comes, early September is the latest time you should consider doing this project. The safest time is February through May. New roots need time before the hard freezes to attach themselves to the soil. If you transplant later the cooler/cold weather will freeze the baby roots and you will lose your roses. You can, however, transplant them in the dead of winter when they are dormant but it is not recommended. This procedure would be appropriate for someone moving during the winter months, thus being able to take their precious roses with them to their new location. A vitamin supplement should be added to the water for fall transplanting. It can also be used at spring time planting, but is not nearly as important as in the fall.
Fall is also the perfect time to double check your roses to make certain there are no dead ones in your garden. Many people inquire about having roses that produce beautiful leaves but no flowers. In almost all cases, the grafted rose has died and the bottom portion of the base stock is sending up suckers, not rose branches. Take a close look at roses that have produced leaves only this past season to see if the leaf branch is coming from below the grafted bulb portion of your plant. If so, dig these plants up and destroy them, they are dead. Roses are not particularly friendly when it comes to using them in the compost, so I recommend you burn them or add them to your garbage.
The month of September is the best month to start the process of "hardening off" the rose bush. This term means that you will need to give them the proper fertilizer to strengthen their roots and prepare them for a long winter's sleep. This is done by applying a liquid 0-10-10 (Phosphorous and Pot Ash) fertilizer two times per month until the first hard
freeze is the recommended application. Do not use granular because it is difficult to dilute and you do not have the time for the rain to wash the granular into the ground. Since we are already into mid-October, make an application now and again at 7-10 day intervals. If we have a late hard freeze, don't hesitate to also do an application in early November.
The two most common questions asked about roses are "When should I prune my roses?" and "Which is the better time to prune, Fall or early Spring"? Many experts here in the Pacific Northwest recommend Spring for pruning. Mid-February or early March seems to be the best time to prune roses. Our famous NW Gardener, Ed Hume, recommends pruning when the daffodils bloom. I used this guideline for the past two years and have been extremely pleased with the results.
Research has shown that it is unwise to prune the rose flower or rose hip off the bush when Fall comes. Rather, when the rose is left to die naturally the rose hip forms a protection for the branches and helps to eliminate severe die backs. These rose hips seem to insulate the branch ends. Whereas, if you prune in the Fall you will have additional die back during the natural wintering process. Remember to prune back just above a growth notch and approximately 10 to 15 inches above the ground level. For many of you who have Tea roses (shorter roses), Floribundas, or Miniatures, you will want to prune them closer to the ground. I use a 8 inch guideline for the shorter ones, and the Miniatures should be somewhere between 2 and 3 inches. Be sure to burn or discard these pruned branches to eliminate the possibility of disease spreading in your composting materials.
Rose experts now say you should NOT leave rose leaves on the bushes during the winter months; the leaves need to be removed. This is normally done during late October, preferably before a hard frost. This process is to help ensure less of the bacterial growth of the Black Spot, Powdery Mildew and Rust mold spores, and any other decaying bacteria that is caused from our wet winter season. I found it doesn't eliminate Black Spot or other fugus problems in my roses, but others have found it to completely prevent these problems. Remember when you removed these leaves they should be discarded or burned. DO NOT add them to your composting materials because the mold spores will continue to grow in a compost pile, making your compost diseased.
The Black Spot mold is not just a menace that attacks roses only. If you have other perennials in your garden, this unwanted criminal will spread to them and infest them as well. Be sure to apply a fungicide for Black Spot on a regular basis to your roses during the growing season and include the surrounding perennials for safety. If you find the Black Spot to be a persistent villain, schedule your applications at least every 7-10 days or until the new leaves show no signs of the spotting characteristics. (SEE last paragraph of this handout for up-to-date information on this unwanted disease).
If you find, as we did in December of 1990, a severe weather force (Arctic Blast!) forecasted you should wrap your rose bushes in cloth, newspapers, paper bags or plastic. The best thing that has worked for me is empty garbage cans inverted over the rose bush.
They are easily handled and removed, and provide an extremely good barrier for the deep cold and high winds. Be sure to removed the coverings once the weather has returned to normal winter temperatures (25 degrees or above is my guideline) or you can cause yourself rot and bacterial problems.
Roses are known to survive temperatures down to about 10 degrees with little trouble. Climbing roses are known to be able to tolerate even lower temperatures. But the guideline most rose growers use is 20 degrees. If you know the temperature is going to dip into the teens for an extended period of time, it would be best to protect them if at all possible.
The traditional way to protect roses is to mound up soil over the canes, to a height of about 20 inches (see attachments). Another recommendation has been to use sawdust, but here in the Northwest, because of our high rainfall, sawdust holds water, causing the rose base and branches to rot. I personally tried the sawdust method in 1991 and lost at least 20 rose bushes to rot, so I do not recommend sawdust in any form.
Another effective protection device is to wrap a wire mesh cylinder around your roses and fill it with leaves that will allow all water to pass through. Oak leaves are the best leaf for this purpose. Under no circumstances should you use Maple leaves (see attachment).
If you have climbers, it is recommended that you take their canes down and cover them with either the Oak leaves or soil. Remember to remove the protection in early spring and tie them back up (see attachments).
Let me emphasize again, these protection recommendations are only for severe weather temperatures below the 20 degree level.
You need to begin your Fall and Winter rose care now because we are running out of time. Fall provides the best time to determine if your need to dig up any dead roses. If so, remember to destroy them and do not add them to the compost pile. Remove all leaves from rose bushes, destroy these leaves. DO NOT remove any of the rose hips of rose petals. Let nature take care of the hardening off process for that portion of your plants.
Apply a 0-10-10 fertilizer for the hardening-off process.
As winter months descend on us, be sure to listen for weather forecasts for severe low temperatures so you can determine if you need to apply extra protection for your plants.
Remember, roses are the most loved and popular of all the flowers throughout the world, so be sure to take care of your rose friends and they'll come back in the spring to visit you happy and healthy.
Let's discuss the Black Spot disease.
For years gardening experts steadfastly recommend using Benomyl for Black Spot. And, every year I lost many roses to Black Spot. But because these experts, including nursery people and several rose society members had recommended the product I continued using it. In 1993 I decided to ask my local nursery people what they recommended for Black Spot and they said the newest and best product was "ferti-lome Black Spot & Powdery Mildew Control", so I bought that product. After faithfully using this new product, my roses continued to died from Black Spot. One day as I was crying and pulling my hair out as I dug up dead plants, my wonderful husband asked me a very simple question. "If a person asked you how to solve this problem what would be the step you would take to help them?"
As WSU Master Gardeners, we are mandated to use the Pacific Northwest (PNW) Insect and Disease Handbooks as our first source for diagnostic recommendations. And guess what....No where in the PNW Disease Handbook does it recommend a product named Benomyl or the "feti-lome" ingredients for Black Spot prevention. Therefore my experience has been a "BUYER BEWARE"!
The PNW Disease Handbook does recommends using Captan, as the first recommended product. You can buy Captan in a canister container at a very high price or in a 5 lb. bag and a much more reasonable price. And you can buy Ortho's Funginex Rose Disease Control in liquid form (pint around $12.00), which controls and prevents the three major Rose diseases. THINK SAFETY when using these products. Be sure to wear rubber gloves, LONG sleeve shirts, and goggles. READ the DANGER section of all chemicals regardless whether they are for roses or noxious weeds. Do not take these warnings lightly. Irreversible eye damage can occur when using these products so invest in some plastic goggles and USE THEM. Applications of every 7-10 days will be necessary until you can be certain that the new leaves are free of the diseases you are addressing.
Another significant finding I have personally discovered, is to use a Dormant Spray with lime sulphur as a winter spray. Spray this product 2 times a month during October through March and even April if you see signs of the Black Spot. If by April you actually see the leaf growth showing Black Spot or Rust or Powdery Mildew you would be wise to start using Ortho Funginex or Orthenex. The first product is strictly for disease control. The second product combines the fungicide in Funginex and Orthene which is recommended for the insects (Aphids, Mites, Thrips) commonly associated with roses. This combination of products may be more economical for you to purchase and can be used for ornamentals as well, (Read the labels for specifics).
Rust and Powdery Mildew is particularly bad in Grays Harbor county due to our low temperatures and high humidity. The Ortho Funginex product listed above will certainly help you with these two ugly diseases.
Aphids and Thrips are the two most common insects that attack roses. Aphids come in different colors (black and green). For Aphids, the PNW Insect Handbook recommends Malathion, Diazinon, Dimethoate, Di-Syston, Thiodan and Orthene in that order. Whereas, the same book source recommends for Thrips: Dimethoate, Malathion, Diazinon and Orthene in that order. Many people use Orthene to control thrips on their roses; while others, alternate the Malathion and Diazinon (See above recommendation for the Orthenex for this problem). Diazinon, Malathion and Orthene can be purchased in separate bottles if you do not want chemicals in combinations. You may want to experiment between products to see which one works best for you. Many people alternate applications of chemicals as bugs sometimes build up resistance to using only one type.
My organic friends use the safer soap products, or lady bugs for insects, and a baking soda mixture for the diseases . However, they have to apply several applications of the soap product; sometimes two to three times weekly. Remember these applications are gone when we have rains. Even insecticides/fungicides have trouble sticking when the rains come so be sure to add a teaspoon of dishwashing soap (Ivory is recommended) to your mixture before applying. This process is called adding a "sticker" because it helps the spray compound stick to the leaves for longer penetration.
Attachments: Diagrams "How To Plant A Rose" & "How To Care For Roses"
Better Homes and Gardens "Roses"
1978 by Meredith Corporation, Des Moines,
Iowa, Library of Congress Catalog Card Number 78-56620 ISBN 0-696-00255-8
1992 PNW Disease and Insect Handbook
WSU/Grays Harbor County Cooperative Extension