I like to do a little research using our NGA database, forums and Help Me Find before purchasing a rose. When viewing HMF, I occasionally read, "Requires Spring freeze protection". Their definition is:
"Spring freeze protection means protecting roses from the harmful effects of late spring freezes on tender, vigorous new growth. Among the roses that are hardy in winter temperatures below 0°F/-18°C is a group that will survive winter but then weaken or die when new growth freezes during the spring. Pruning and fertilizing a rose in early spring promotes lush but tender new growth.
Late and unseasonal spring freezes may involve temperatures no lower than 20 to 24°F/-7 to -4°C. The effects can be devastating, killing new canes and leaving those that survive damaged and susceptible to canker. Late Spring freezes do not occur everywhere. Rosarians who live in such climates resort to a number of strategies, including late pruning and minimizing spring fertilizer."
This is what many gardeners experienced this past season. I could not help but notice that the roses grafted to multiflora were the ones effected. Recently a passage from a book entitled, Rose Growing Complete by E.B. Le Grice was brought it my attention. For those who may have this book please refer to page 32. It reads as follow:
"A further popular stock is the R. multiflora (polyantha). This is a rapid grower, with many surface roots, and makes a large tree. Those grown from seed make a good stock for floribunda types, but being more surface rooted suffer more rapidly in dry weather, and because of this may fail to bud well. Another fault is its tendency to early growth which can lead to damage in exposed places or "frost pockets". Easy to grow from from cuttings, and easy to bud in this form, the plants produced suffer from freezing, and the root system dries out easily, so making transplanting less certain. A further disadvantage is its dislike for alkaline soil."
There is lots of valuable information here if you break down these sentences. "rapid grower" and "early grower" - both are bad for unseasonable fluctuating
temperatures. On the north eastern shores of Long Island we had about 8 days of temps between 60 and 70 degrees in Feb. followed by temps falling rapidly to 19 degrees for 3 days and nights. Then a similar scenerio repeated in April again.This resulted in roses leafing out and die back. Rose canes grafted to multiflora displayed reddish maroon colored patches. Effected canes had to be pruned inches below the colored patches till the cane piths appeared their whitish normal color. In some cases, an inch from ground level.
Le Grice states: " being more surface rooted suffer more in dry weather". We've had a drought here over the last few years. However, we have had a lot of rain this Spring. Example: I took a pH reading in early Spring - read 6.8. - I was happy with that reading. Repeated another reading yesterday in the exact same location - and it read a surprising 6 - big difference resulting from acid rain. Solution: added lime. A solution for surface roots: slow drip watering - will encourage roots to go deep to search for water.Offer water every few (4-5) days rather than everyday to train the roots to seek water deeply into the ground. Lots of nor'eaters here on LI - winds 50+ (3 this past winter).I do stake my roses and have four 12" stakes secured into the obelisks. http://www.garden-view.com/dee...
Le Grice: "plants suffer from freezing". I have found mounding/hilling up and mulching in late Fall through late Spring to be helpful. Prune in LATE Spring as pruning encourages new growth. Same with fertilizing.
The roses that were effected (canker) by the Spring/Thaw winter were ALL grafted to r. multiflora . However, grafted Red Corsair, Stormy Weather, Jolie, Garden of Roses, Green Ice & Reine Des Violettes were not effected. ALL own root and roses grafted to Dr. Huey showed no damage. The Kordes roses that I bought were ones that were tested to be suitable as own roots. I may have created unnecessary problems for myself by purchasing them grafted on multiflora. 30+ yrs. ago I purchased all my roses from J&P they were grafted on Dr. Huey. I have read in the past that multiflora are susceptible to viruses.
http://scvrs.homestead.com/Roo... - read paragraph 3 and 8.
UCDavis is using multiflora to test for viruses.
http://www.amerinursery.com/pl...
"Before a new rose can be entered into the clean stock block, the rose needs to pass three kinds of testing. First, roses undergo molecular tests (PCR/ELISA) to determine if they are positive for the rose viruses that have been well characterized and detection protocols are readily available. If they pass that test, then there are two biological tests they will also need to pass. One is being bud-grafted onto a virus sensitive rootstock called R. multiflora ‘Burr’s Multiflora’ that shows strong symptoms when infected. The rootstock is checked for symptoms over two years."
Note the description: "a virus senstive rootstock called r. multiflora".
Le Grice also states r. multiflora dislikes alkaline soil. Perhaps when purchasing a new rose in addition to one's zone the pH of the soil should be considered. I think it would be beneficial to all if we disclosed not only our zone but whether the rose we are discussing is grafted or own root, as well as our gardens pH (acid, neutral, alkaline). Please feel free to view my NGA rose database esp, if you are in zone 6b and leaning towards acidic soil. All 100+ roses are thriving with the exception of Blue Skies and Blue Girl (I may move them to see if that helps - otherwise they are goners - oh well...)
Margie, Long Island, 6b, pH 6.5 - 6.8

That's a lot of good information, Margie.

Thank you for posting it ...

Margie!

Margie ..

I have been re--reading my LeGrice book. It's another one I saved ...

Some of the advice is old-fashioned because they have learned a lot about roses since it was written, but there is a LOT of good common sense rose gardening advice in that book. It's very much worth reading.

Knowledge is created through the ever-changing development of experience.

Thank you, Margie for the wonderful passage!

It is heartwarming to find experts such as Le Grice reporting what we have been observing.
- Late frosts kill new growth, sometimes with devastating consequences
- Which means that activities that encourage early new growth: pruning, fertilizing, watering may set certain roses up for failure.
- Multiflora rootstock pushes up new growth earlier in spring than does Dr Huey, and (certain) own root varieties.

And to get confirmation about what Lyn has been saying: that one reason for Dr Huey rootstock is its tolerance of high pH soil.

Thank you, too, for posting your list of roses. What a great resource it will be for people gardening in similar conditions!

Steve, thank you for your follow up post and excellent outline.
A virus sensitive rootstock such as multiflora means that it may express symptoms faster or more readily.
Le Grice stated multiflora is a "rapid grower" and a "early" grower. Because of this, multiflora may be much more susceptible to fluctuating temperatures than Dr. Huey.
Multiflora will bud much of the Spring through Fall. Dr. Huey is best at about flowering time while the multifloras don't demand the higher heat Huey do for bud taken and growth push. "That supports the possibility that multiflora is more susceptible to fluctuating temperatures. Multiflora are ready to break and push growth with any warmth where Huey waits until its threshold is reached. Those on the multiflora stocks start early and keep going later as their heat threshold is lower."
The above budding information was requested by me and provided to me by the hybridizer Kim Rupert. Thank you Kim for helping me piece this together.
Margie, Long Island, Zone 6b , acidic pH

To me it means that if a rose is completely cold hardy - (USDA zone 5b, for example) then growing it on multiflora rootstock would make sense because we get a lot of good rose-growing weather in the months of March and April. It also means that I need to be more of a maniac about watering cold hardy roses in those months. I've had very good experience with Julia Child, Selfridges, Caramella Fairy Tale, and Europeana on multiflora rootstock; although Europeana requires prodigous amounts of water. I've not noticed that Dr Huey rootstock has held back many of my David Austin roses, although I cannot remember which rootstock Graham Thomas is on. It's doing very well.

On the other hand, if a rose needs spring freeze protection - using the HMF terminology, I am better off choosing a rose on Dr Huey rootstock. Because it stimulates new growth, I am also better off if I do not prune such a rose until the last week in April. Our 90% late frost is in mid May. Seems to me that I need to withhold water before that. Or water in a stingy manner. Those new canes are especially vulnerable, and if the roses' roots are not sensing adequate water, they will not push new growth. In very late April or early May, with the Accu-Weather forecasts in hand predicting no nightime weather below, say, 40F I can start generously watering those HT roses that need winter protection. In no time flat, they will push up new canes.

This is a distinction I wish I had been able to make before today. I might have saved quite a few good roses.

---

Water this, but not that. Prune this now, but that later. Pruning is fun in February; but it is a chore in late April. Suddenly it occurs to me...

Up until this point in time I had imagined that I might be able to grow roses as landscape plants, like the forsythia, the daffodil, the opuntia cactus. But suddenly I am assaulted with the idea that my roses have become little bloom machines and I am the laborer who operates them. Not sure I am comfortable with this view of my relationship to my garden. I feel an impulse to fill the garden with confederate jasmine except that it's not completely cold hardy here.

Steve ...

I would not recommend holding back water to avoid stimulating growth. Roses are not drought tolerant plants and withholding water puts them into "survival mode".

There are many variables that have to come into play at the same time to trigger growth. It's not only ONE variable or even two variables because each rose is different.

This year my roses got pruned all winter with the deer chomp method of pruning. This did not stimulate growth. We also got over fifty inches of rain. This did not stimulate growth. In fact, my first flush was about a month later than usual in spite of the plants receiving what we have been taught would stimulate growth because the other variables were not in play. Even the species roses growing all around my property bloomed a month late.

My average last frost date is mid-May, but my average HARD frost date is mid-March. It is the hard frost date that is significant because a hard frost is a killing frost.

I have been re-reading LeGrice's book while I have been playing catch-up in my garden. He spends a lot of time writing about when and how to prune and, more importantly to my mind, why to prune.

With Margie's nor'easters, the temperature fluctuations are strong indicator that multiflora is not a good rootstock for her garden.

I don't know what the ph of the soil is in your garden, but if it is alkaline, that would be a strong indicator that multiflora would not be an ideal rootstock for your garden. In Margie's first post, she quoted LeGrice as saying, " A further disadvantage is its dislike for alkaline soil."

Another variable ..

Unfortunately, the information that Maragie got from Kim and from LeGrice's book is not readily available, so people are purchasing roses without having the necessary information to make a good buying decision.

btw .. LeGrice's book was one of the homework assignments Kim gave me when I first started working with him ...

I'm assuming when they say multiflora doesn't like alkaline soil, that means a somewhat high ph? I'm curious about this because multifloras are rampant here and quite invasive. Soils in central Kentucky are limestone based and tend to be slightly alkaline, but just above neutral. This is why this is known a bourbon country- the "sweet" ground water makes good bourbon.

Neal .. like most species roses, there are several types, for a better word, of multiflora. Each has adapted to the local environment.

There are multifloras that are heavily thorned and others with no thorns. Some are tall, while others are dwarf and so it goes. However, there are enough common characteristics that they are all classified as r. multiflora.

This one of the reasons I say that every rose we plant is an experiment. We really don't know until we plant the rose in our garden.

How can a buyer be certain that the multifora used in the grower's fields is the one that will work in your area ?

Using most multiflora root stocks in southern California resulted in weak and poor performing roses. Note: southern California is where I started growing roses and where I know more about the soil. However, the soil alkalinity in that part of the country was not caused by limestone. Southern California was covered by the sea for eons. The native soils are very alkaline for a different reason than the soils in Kentucky.

Another variable. All it means to the buyer, is that if they see a rose they have purchased that is grafted to multiflora root stock, instead of blaming the rose or the nursery, they should look at the root stock as a possible reason for the rose not thriving in their garden.

I am always saying, "It depends on the rose", but another way of looking at growing roses is to remember there are few generalities that can be applied to roses, because there are always roses that prove those generalities don't apply to all roses.

It's variables on top of variables on top of variables.

Also, some roses are just plain duds with pretty flowers ...

RoseBlush1 said:Steve ...

I would not recommend holding back water to avoid stimulating growth. Roses are not drought tolerant plants and withholding water puts them into "survival mode".

How would you recommend I treat the roses to avoid stimulating growth? You said earlier that roses do not put out new growth when they have insufficient water. Is it better to have a plant that dies completely stone-cold dead because it has generated frost-tender new growth too early, or to have a plant that goes into early May slightly retarded in from lack of water?

RoseBlush1 said:
There are many variables that have to come into play at the same time to trigger growth. It's not only ONE variable or even two variables because each rose is different.

Just, please, name precisely the variable that would delay growth until the danger of frost is over. Maybe I can dig them all up and put them in a refrigerator until mid-May? Or employ haystacks like the ones immortalized in Monets famous paintings?

RoseBlush1 said:
This year my roses got pruned all winter with the deer chomp method of pruning. This did not stimulate growth. We also got over fifty inches of rain. This did not stimulate growth. In fact, my first flush was about a month later than usual in spite of the plants receiving what we have been taught would stimulate growth because the other variables were not in play. Even the species roses growing all around my property bloomed a month late.

Yes, and you had fifty degree days while we had seventy degree days in March and April. Our spring days this year were a full ten or fifteen degrees warmer than yours. While our nights were equally cold. Many cold hardy roses did not go fully dormant here. Mme Alfred Carriere did not finish losing fall foliage until most of the new foliage was in place in mid April.

Here is a photo of Grande Dame in late April, four weeks after being pruned. Darn thing is nearly dead. We had no "HARD" frosts since pruning. Precious few light freezes. I expected six. I doubt we got three. It was uncharacteristically warm, by which I mean 40F nights from mid-March until the second week of May. This HT rose, which is normally a rampant grower even in April, remains in early June just about dead. And except for one very desiccated Olympiad which is a goner and one Fragrant Plum whose roots were nibbled off the day it was planted, GD has not caught up with any of the thrity bare root roses from Edmunds planted in late April.

This is what happens to most HT roses here in spring. It never happened to this rose until I started following your advice, pruning after the hard frosts are over and providing extra water. I lost Charles de Gaulle this year even more convincingly from early watering. (Yes, watering in March and April definitely helps the hardy floribundas and shrubs. It even helps the cold hardy Kordes HT roses. But because it stimulates early growth it kills HT roses that "need spring freeze protection".)

RoseBlush1 said:
My average last frost date is mid-May, but my average HARD frost date is mid-March. It is the hard frost date that is significant because a hard frost is a killing frost.

I have been re-reading LeGrice's book while I have been playing catch-up in my garden. He spends a lot of time writing about when and how to prune and, more importantly to my mind, why to prune.

With Margie's nor'easters, the temperature fluctuations are strong indicator that multiflora is not a good rootstock for her garden.

Yes, well, I have lived in New Jersey and grew dozens of roses for more than a decade. The temperature fluctuations where I lived were just a bit larger than those of Long Island. I can tell you categorically that in terms of temperature fluctuations the mountains of the West make New Jersey look like a well regulated tropical paradise by comparison.

And of course, every rose responds differently. We define hard frost in a particular way, sometimes because of specific connections to the physical world. Zero degrees Fahrenheit was defined as the lowest temperature one could bring of a saturated saline solution to before it froze, whereas thirty two is where pure water freezes. So there is a sense in which freezing is a range of temperatures from zero to thirty two degrees Fahrenheit. So it is silly to make too big a deal of the formal definition of hard frost.

It is just as silly to assert that a rose cannot distinguish forty degrees Fahrenheit from eighty degrees Fahrenheit. A rose kept at 40F will behave in a markedly different manner than one kept at 80F. If it were not so we'd not build greenhouses to grow roses. Nor would we employ refrigerated storage for bare root plants.

So why must we pretend that every rose that sees 40F nights every night for six weeks will behave precisely exactly like one that has seen 70F nights for six weeks? I see what happens to greenhouse roses when planted here with 40F nighttime weather. The soft new foliage dies. No hard frosts. No light frosts. Just 40F nights every night. And this is not just HT roses, either. For some plants the definition of 'hard frost' corresponds to one useful distinction of many. Sometimes there are two or six other thermal phenomena that are more important.

Sometimes it does not have to get colder than 40F to kill a rose. Especially one that has recently been pruned and provided plenty of water. One that is growing vigorously as compared to one that is growing tentatively. I see it every spring in my garden.

RoseBlush1 said:
I don't know what the ph of the soil is in your garden, but if it is alkaline, that would be a strong indicator that multiflora would not be an ideal rootstock for your garden. In Margie's first post, she quoted LeGrice as saying, " A further disadvantage is its dislike for alkaline soil."

Another variable ..

Yes. But one or two Kordes HT roses do fine on multiflora rootstock here, provided they are not nibbled by gophers. So, too, hardy floribundas and shrub roses. We average 20 inches of rainfall here, there's quite a lot of local vegetation, and no limestone. I'm not going to try growing blueberries in this soil, but I have no reason to believe that multiflora rootstock puts cold hardy roses at any disadvantage here. What is the pH cutoff below which any advantages multiflora rootstock might confer becomes a liability? Is it pH > 6.8? 7.2? 7.8? 8.5?

The problem with my HT roses, to the extent that it comes from rootstock, is almost certainly because it is more precocious in spring weather. It is certainly not a problem unique to multiflora rootstock; but I have reason to believe it is a problem magnified by it.

RoseBlush1 said:
Unfortunately, the information that Maragie got from Kim and from LeGrice's book is not readily available, so people are purchasing roses without having the necessary information to make a good buying decision.

Yes. Lack of good information is clearly a big problem for rose gardeners. Also, it is useful not to confuse unavailability with irrelevance. I do not believe a word of Edmund Le Grice's work simply because he is an authority. I believe it because it is consistent with my experience.

Is there any authority who makes a distinction between leaves generated on old hard wood and leaves generated on new canes or new soft growth at the ends of old hardened canes? I ask because in my climate the former tend to get through much cooler weather than the latter. It may be a full ten or even twenty degrees Fahrenheit difference.

Great discussion, Steve. Thank you for participating ...

How would you recommend I treat the roses to avoid stimulating growth? You said earlier that roses do not put out new growth when they have insufficient water. Is it better to have a plant that dies completely stone-cold dead because it has generated frost-tender new growth too early, or to have a plant that goes into early May slightly retarded in from lack of water?

I wouldn't. It makes no more sense to me to grow roses that are not sufficiently hardy for your garden that it would be for to grow tropical plants. In England, when tea roses were first introduced, they only grew them under glass because the roses could not survive the winters. They had a milder climate than you have in your garden. Growing roses that are not hardy enough for your climate is like trying to grow bananas in your climate. If you want your roses to live, it works better to grow the roses that are adapted to your climate conditions.

Depriving a non-drought tolerant plant of water, to me, is the same as depriving an animal of water. It weakens the plant and the animal and makes it more vulnerable to any kind of stress. If the stress is extreme enough, the plant or animal will die.

Just, please, name precisely the variable that would delay growth until the danger of frost is over. Maybe I can dig them all up and put them in a refrigerator until mid-May? Or employ haystacks like the ones immortalized in Monets famous paintings?

Again, I wouldn't plant anything that wasn't suited to my climate. Heat causes more damage to roses in my climate, so I specifically chose plants that could survive that kind of stress. There are many roses I truly love that I don't grow because they are not heat tolerant.

Yes, and you had fifty degree days while we had seventy degree days in March and April. Our spring days this year were a full ten or fifteen degrees warmer than yours. While our nights were equally cold. Many cold hardy roses did not go fully dormant here. Mme Alfred Carriere did not finish losing fall foliage until most of the new foliage was in place in mid April.

If you are getting your weather information for Weaverville from Accuweather, the information is skewed. The weather reported is from down in the Valley in Redding. It does not reflect Weaverville weather ... Yes, we did have a warmer winter than the norm for Weaverville this year.

(Yes, watering in March and April definitely helps the hardy floribundas and shrubs. It even helps the cold hardy Kordes HT roses. But because it stimulates early growth it kills HT roses that "need spring freeze protection".)

What kind of winter protection did you give your roses ? How old was your 'Grand Dame' ? Was it water stressed before winter ?

Here is a photo of my 'Grande Dame', severely deer chomped this winter, with fifty inches of rain. It got a LOT of water. The rose is in its second year.

And of course, every rose responds differently. We define hard frost in a particular way, sometimes because of specific connections to the physical world. Zero degrees Fahrenheit was defined as the lowest temperature one could bring of a saturated saline solution to before it froze, whereas thirty two is where pure water freezes. So there is a sense in which freezing is a range of temperatures from zero to thirty two degrees Fahrenheit. So it is silly to make too big a deal of the formal definition of hard frost.

Botanically, a hard frost is defined as 25 degrees or lower. That is a killing frost. I was talking with a vintner about how he saved his grapes when we have an unusual hard frost after they have started their growth period and have young fruit on the vines, and he told me they flood the fields and mist the plants to create an "ice shield" to protect the young fruit and foliage. I have found that a well hydrated plant seems to have a better survival rate in my garden.

Is there any authority who makes a distinction between leaves generated on old hard wood and leaves generated on new canes or new soft growth at the ends of old hardened canes? I ask because in my climate the former tend to get through much cooler weather than the latter. It may be a full ten or even twenty degrees Fahrenheit difference.

There's lots of good information about that and the kind of wood that can tolerate cold. You just have to do your research.

I have a long list of hybrid teas that are cane hardy in Nebraska, zone 5, with various kinds of winter protection. Cynthia grows over 700 roses in her garden and keeps meticulous notes. All of the roses your mentioned in your nursery report are not on her lists.

I think I am going to try wrapping the multiflora grafted roses in burlap prior to this coming winter. I read somewhere about creating a burlap tee pee. If the temps drop suddenly I think they will be warmer (stable) and perhaps not effected as much. We had 3 nor'easters this past winter with 50+ mph winds. I'll keep you abreast of the results. If the burlap doesn't help to protect them from fluctuating temps and wind, I can always purchase Kordes own roots - that might be the best solution for me in the long run. The other alternative I have is to graft the roses to Dr. Huey myself - not likely. I was hoping this year would be the last year of planting anything. I am at the stage in my life where I want to do maintenance period and just kick back and enjoy my garden.
Margie, Long Island, zone 6b, acidic soil