In zone 4, it is time to sleep not grow....

I would wait till spring.

It depends on how well established they are. Woody based plants (like most vining clematis) will benefit from a fall fertilization as root growth is active at this time of year and soil temps conducive to nutrient uptake and metabolization. You will want to avoid a high nitrogen content fertilizer, as this will push new foliar growth which is NOT what you want to encourage. I prefer organic ferts, as they are by nature slow release and the nutrients are available over an extended period. Depending on the NPK ratio of the rose fertilizer, it might work well. Most rose fertilizers tend to minimize nitrogen levels in favor of increased root growth and flower development.

I agree with gardengal. Keep it organic and slow release and low nitrogen and you can't go wrong. The roots will continue to grow and take up the nutrients and the plant will be all the happier for it in the fall. Good news on the second flush of blooms on your type IIs Shirley!

OOPS! I meant to say that the plant will be happier for it in the spring.

I guess I missed something. Is rose food considered "organic"?

Some rose fertilizer is, some isn't. 'Organic' fertilizer just means it is formulated from naturally occurring materials, typically plant and animal by-products, rather than a synthetic formulation which is chemically based. Because of their ingredients, organic ferts are typically always slow release, whereas synthetics more often than not are fast release. It's a bit like comparing fast food/junk food from a drive in with a nutritious, well-balanced home cooked meal.

The reference to rose fertilizer did not necessarily specify organic - rose fertilizers just tend to be rather low in nitrogen in favor of potassium and phosphorus. I'd still pick an organic over a synthetic though, but that is my personal choice.

I would too gardengal. I like using compost (homemade if available), compost tea, alfalfa pellets or tea made with alfalfa pellets, grass clippings, etc. Along those same lines, phosphorus is one of the three ingredients in typical fertilizers and stimulates root growth which is normally in its ramped up state during the fall of the year. Potash or the K in your typical N-P-K fertilizer is used on lawns in winterizer fertilizers to aid in preventing winter kill of grass. I am not sure of the exact mechanism this is supposed to work by but I believe it is to help the roots in some fashion. Sounds like something that might be applicable to clematis as well.

I noticed that Shirley is from zone 4 and the 'opposing' view folks are from zone 7-8.

I think this is another example of zone consideration. We already had a night frost a couple of days ago. Once the leaves die off and photosynthesis stops, there is no more metabolic energy needed to support further root growth.

Adding NPK or PK in October in zone 4 may not hurt the plant, but it is not going to be of much use to the plant either. Perhaps it could help by being available next spring to give an early boost (assuming it does not leach away by then), but in the Spring, the plant needs nitrogen, so one would have to apply a higher N fert. anyway.

I guess my feeling is that fall fertilization in low zones needs to be done by the first of September, not October, to stimulate root growth. Other wise just wait till Spring because your just springling money on the ground....

Hal

...stating in a more general rule.... fall fertilization should be done at least 6 weeks before your frost date.

Hal

Hal, I certainly don't wish to argue with you, so please take this in the manner in which it is intended. It is not a factor of climate or zone considerations at all, but an understanding of plant morphology. The lack of photosynthesis occurring does not mean a plant has stopped growing. During the early period of dormancy, after frost and leaf drop, woody plants continue in a period of very active growth, but it is all underground. Root elongation is most prevelent at this time of year and will continue even after the soil freezes, but at a slower rate. Soil temperatures, available moisture and access to nutrients, plus the ability to metabolize them, are all excellent reasons for fall fertilization of woody ornamentals regardless of your location. Frost really has very little to do with it, other than the recommendation is to wait until AFTER a good frost before applying fertilizers. The same logic and reasons for fall or early winter fertilization of lawns applies to other plants as well, given the caveat of a low nitrogen formulation. Spring fertilization produces a different reaction in plants based on their biological mechanisims - it encourages stem and leaf growth and the development of flower buds. Development of a strong root system is encouraged by fall fertilizing and plants fertilized in fall will start the spring growing season in much better condition below ground than if one were to wait. Strong roots equal strong plants, specially when it comes to clematis. And believe it or not, nutrient uptake at this time of year actually produces a chemical reaction within the plants that tends to increase hardiness and resistance to cold weather. Fall fertilizing is a good thing!

BTW, the photo of your home on your member page is charming and your garden is gorgeous.

I think roots DO Continue to grow during the winter...that is why planting in the Fall is so advantageous..It allows the roots to grow and get established over the winter...IMHO...Jeanne

I agree and have made the point several times that root growth is most prevalent in the fall. The fact that the first frost has occurred has no bearing on the soil temperature. Hal, remember you were even the one who dug up the information that root growth is optimal up to close to the freezing point of the soil and that the soil temperatures stay relatively constant the further down in the soil you go.

Gardengal..may I ask you some questions?..Could you tell me just exactly what you feed your clematis in the fall and If you are using something that you do buy at a garden center what exactly is it?..Thanks so much...Jeanne

Okay Jeanne, this could get a little confusing, so bear with me! If I fertilize in fall (and I don't routinely do so - it depends on a number of things, the biggest of which is my schedule), I use a balanced fertilizer, Dr. Earth's Organic 7. With the exception of an acid based fert for rhodies, etc., it is the only commercial fertilizer I use.

The NPK on this product is 4-4-4. If I were going to use a synthetic or chemically based fert, I probably wouldn't select a balanced formulation as the N content would be too high for this time of year. But organic fertilizers work differently than the synthetics do and their nutrient contents are lower and this product does the stuff for me.

I also have rabbits and I do recycle their waste pretty religiously on anything that I consider to be heavy feeders, most typically my roses, clematis, hydrangeas and lily plantings. A clematis (Belle of Woking) planted close to the bunny condo is an incredibly vigorous and heavy flowering one for me and I attribute a lot of that to the effects of the nearby source of bunny poop :-) And I mulch with compost in both fall and late spring.

I do not routinely fertilize anything other than container plantings. I think as a whole we rely on fertilizers too much and tend to overdo - generally, fertilizing is necessary only if the plants indicate they are lacking in specific nutrients and a soil test indicates what that lack may be. I have worked hard over the years to develop a rich, high organic and well draining soil and that is usually sufficient for most plants, combined with whatever regular mulching I do.

The Dr. Earth products are excellent and I swear by their ferts and soil amendments and the soils and mulches from their sister company, Gardner & Bloome. I particularly like that their fertilizers (and the soils) are innoculated with beneficial soil organisms and mycorrhizae. This encourages very strong root systems and greater resistance to environmental stresses, like drought. I don't know how widespread their distribution is (it is a California-based company), but if you can't find it locally, I'd urge you to talk to your local garden center and see if they will carry it.

Here is a link that might be useful: Dr. Earth products

Glad I checked out this discussion. I, like Hal, would not have thought that fertilizing in the Fall would be of any benefit, due to the soil freezing in my Canadian zone 4b, and the vines above ground looking like dead sticks once the leaves die and fall off. That's why I like this forum so much. I am always learning something new about gardening from all you knowledgeable gardeners who so generously and patiently share your gardening know how. Thanks.

Hi everybody be sure and throw a little lime on top this will intensify the color of your flowers like you can't imagine we did this on the flower farm to make the colors brighter. good discussion wishing you all well

Thanks to everyone who responded! What a great discussion! I think I'm going to go ahead and try the rose fertilizer this fall and I'll report back in the spring and let everyone know if I see a difference in my plants. I had very good luck with my clematis this year and hope they do as well (if not better) next summer. I do add an organic mulch in the spring in addition to the Miracle-Gro. By the way, we have not had a hard frost here in Wisconsin yet this fall. The temperature has gotten down to the upper 30's a couple of times.

Thanks again for all the very useful information - love this forum!

Shirley

OK, you probably are right, and I did point out that soil temperature does not correlate with ambient temperature.

I guess I am tgrying to learn more about this while trying to make sense of everything I know, part from my upbringing ( my grandfather, who was a farmer and gardener, told me it was a watse to fert. in the fall), to my education, I am a health professional and know about animal cell physiology.

But I am ignorant about plant physiology and now am intrigued. Part of what you say Gardengal and Miguel makes sense, but parts do not. Inorder for any cell to proliferate ( plant or animal), it must use energy in the form of ATP. Usually for plants this comes from photosynthesis. If roots continue to grow after the leaves die back, then the roots cells must be using stored energy in the form of starch or sugar. That is not an unlimited supply, so roots can not just go on growing throughout the winter. My limited deduction ( from animal cells) would be that hastening the consumption of that stored sugar supply ( by fertilizing), would be like robbing the grain bin, maybe good way to grow fast in the short term, but in the long term you come up empty and starve before spring.

So, I am going to research this further, and I am sure I will then better understand what you surely are correct about.

thanks,

Hal

Hal, I think that where you are missing the picture on several points. One is that roots can serve several functions. One of them, above and beyond anchorage, absorption, and conduction, is storage. ATP can be stored in the roots. ATP as you well know, as a biology oriented person, consists of adenine, the sugar ribose, amd three phosphate groups. The three phosphate groups have a very strong negative bond to each other and breaking these bonds releases a large quantity of energy. The salient point is that each ATP molecule has three of these bonds that can be broken and doing so releases a rather significant amount of energy.

Secondly, in order for these bonds to be broken, an enzyme or multitude of enzymes are called into play. Enzymes are temperature dependent. As was pointed out in the information that you provided, the rate of root growth decreases with decreasing soil temperature. This is due to the decreased soil temperatures causing a decrease in enzyme activity in the root zone of the plant. Therefore, a plant will not deplete its energy reserves because as the ambient temperatures decrease, the enzyme activity will decrease therefore root growth will stop or become so slow that it is imperceptible--this is commonly referred to as a temperature or enzyme regulating step or feedback loop. In those areas where the air temps never go below freezing, the foliage won't drop off so photosynthesis will continue (since photosynthesis is enzyme driven) albeit at a much slower rate and root development will continue. In those areas where the air temps drop and frost occurs and the foliage is removed as a result, the soil temps will eventually drop to a point where enzyme activity drops off and therefore root growth will cease or slow to an imperceptible point. I don't think that anyone ever said that in all zones that root growth will continue indefinitely. I think that what was attempted to be pointed out was that fall fertilization can lead to root growth because there is a lag in the time that air temperatures drop and when the soil temperatures reach a point that root growth is slowed to a crawl due to decreased enzyme activity.

what a great thread. I've been wondering about this very topic as I've lately seen casual recommendations here and there about fall fertilization for trees and shrubs. I've been meaning to ask and then here's this great discussion...

Miguel,

I think you and I are saying the same thing but coming up with totally opposite conclusions.

I guess another way of stating my position is what good can mineral nutrients (PK) do when there is only a finite energy source with just the roots in late fall ( no photosynthesis for ATP production). it seems to me that stimulating root growth in that condition would deplete the energy stores more rapidly, and leave the plant with less reserve.

My position would be that the fertilization needs to be done well before fall defoliation.

Hal

I just use manure at this time of the season and forget the rose food, etc.... It's so simple and my plants love the stuff.
Suzy

I wish I had access to the real stuff. The 'manure' you purchase at the garden stores is basically compost.

Hal

Halds, that's exactly what I get, composted manure from my nursery. The clematis and other perrennials love it, still. Believe me, I can smell the manure in it, lol.
Suzy