Clematis

[Kat 0]

Hi Janet and Steve, THanks for setting up this website. It is great to have the forum and your expertise at our fingertips (literally).

My question is that I had a clematis (Jackmani) for several years planted on a fence. It was fabulous! Several years down the line it's leaves started turning yellow. I put lime on it and it did green up. BUT, after several years of adding lime, I believe the soil had too much of a buildup of acidity.  

If I remember correctly, the leaves started shriveling up and falling off. SO, I dug out the soil and replaced it. But I stil have the same problem. The clematis does not like it there apparently. Yet it did soooo well there for many year initially.

AND, I have another clematis planted just 2 feet away. Does great.

[Janet Macunovich 32]

Glad we can help. Community's important. Steven and I think that no single gardener, not anybody, can ever know it all but when we put together all the different years and growing situations a group has known there's a pretty good chance of finding our collective way.

Sorry about the clematis. Hate to see a plant that was pretty, fail. But it happens. More often than you probably expect.

 

I hope none of the following sounds too negative; it's just written as it comes to mind.

Beginning with that  first thought is "ah well.." Because the majority of large flowered clematis (some of the Jackmanii varieties included) do well for a while -- maybe a few years maybe ten -- and then go downhill. The soil pH (relative aciidity/alkalinity might have had very little to do with it. A widespread and increasingly common fungus might be involved. Or a virus. Or dry soil, or rodents. We'd remove the one that's failed, dig over the bed to add organic matter, loosen the soil and make sure the drainage is good, and then plant a small flowered clematis instead -- straight species Jackmanii or better yet C. viticella or C. violacea.

 

Then, things that can make a clematis wane:

1) The clematis in going yellow may have been expressing virus symptoms (Clematis mosaic virus; I'll post a photo soon as I can). It starts out with almost pretty mottling-without-death on some leaves and year by year the leaves become more yellow, the plant weaker and finally dying. If that was the case, there was no cure. Plant viruses can't be cured. The plant might remain strong enough to outgrow its effects but it never goes away.

 

2) The shriveling leaves as main clue: The clematis might have been dying back in sections because of clematis wilt, a fungus infection that plugs the water conducting system and is pretty much incurable. Resistant to most fungicides including all that are available to homeowners. Wilt is the reason a good number of growers abandoned production of the very susceptible large flowered clematis hybrids (including some of the Jackmanii types) in favor of smaller flowered varieties from more resistant species.

 

3) Dry soil and/or low fertility can weaken a clematis and even cause it to lose leaves.

 

4) Some rodents including the mouse-like voles, can undermine a clematis, eating roots from below.

 

5) pH is tough to change, and is rarely as important to plant growth in our gardens than what seems the case from all the pH testing kits being marketed and all the coverage in gardening books.  (Long topic. I'll look for the articles we've written and put links here; page 4 of What's Coming Up #28 has a good summary; for more we might have to post items from archives as they probably haven't yet made the cut for posting on the website. Too dull and technical.) Upshot is that unless we have a soil test that says with certainty that the soil is very acid (would have had to be below 6.0 which is into the very acid range, to really hamper a  clematis) or very alkaline (over 7.5 would probably put a crimp on) then we don't add things meant to change the pH. Lime makes soil more alkaline. Sulfur makes it more acid. Either one, especially the lime, can build up and kill a plant. In Midwest soils that tend to be alkaline to begin with, the lime's probably the worse one. (In farm fields heavily fertilized with ammonia fertilizers, acidity can be a problem, thus agricultural books recommend regular liming.The same is not often true in gardens.) So the lime you applied may have begun to cause trouble. Very few plants do well in very alkaline soil. Even though it's said that clematis like lime/alkalinity that's a very relative thing that might also be phrased they don't like it acid or they like it more neutral than acid. The greening up after the first liming may have been coincidental rather than a consequence.