How to prune and care for your Clematis:
If you've been successful growing a clematis for a couple years, you stand back and look at that tangled mess of stems and "Say What?" What to do with the mess is a question I get asked multiple times a year. I will try to address the complex descriptions you will find in regards to pruning and then I will give you the Open Air simple solution.
Clematis are separated into three pruning groups, 1,2, and 3 or sometimes you will see them classified as A, B, and C. The tag will tell you what classification group a clematis falls into. If you no longer have the tag but remember the name you can look it up on line. If you don't know the name, let us know and we'll try to figure out which one it is. After growing clematis for 24 years, we've pretty much grown them all.
Group 1 clematis: These clematis flower in the spring on growth from the previous year. In other words they bloom on old growth. Prune these vines right after they finish blooming in spring. The new stems that grow will then have enough time to make flower buds for the following year. How much to remove when pruning depends on the vine's vigor and the support you have used to grow it on. Try not to prune into hard wood that has developed low on the plant. If the vine has become a tangled mess you can prune it hard, 24 inches in height, but you will sacrifice some bloom the following spring. The great thing is there are few group 1 clematis that are hardy in our area and chances are really good you don't have one. Pretty much you can disregard everything you just read.
Group 2 clematis: These clematis bloom in late spring or early summer, then bloom again sporadically, on new shoots and old stems. The major flush of spring blooms come from old growth but they will continue to bloom on new growth but with less flowers. The old growth will produce some very nice, large flowers. If you cut back these clematis drastically right after the first bloom, you miss out on much of the summer show. If you prune just before growth begins, you miss the spring flush. The best approach with a group 2 clematis is to thin out old dead canes before growth begins in late winter or early spring and than do this again once the spring bloom has finished. An alternate plan is to severly prune the plant back by half every other year. You can also cut the whole plant back drastically every few years just before growth begins, with little or no pruning during the time inbetween. Somewhat confusing but I'll make it fairly simple if you keep reading.
Group 3 clematis: These clematis bloom in late summer or fall on new growth produced earlier in the season. These are the easiest vines to prune as you simply cut all stems back to strong buds within a foot or so of the ground each spring. This is what you should do with Sweet Autumn clematis and other fall blooming clematis.
Let's simplify the entire process. Nearly every clematis grown and sold in our area is a group 2 clematis. You may have a group 3 clematis and we do sell a few very nice varieties. After growing clematis for 25 years this is what I do.
I do nothing until spring. This is usually very late March and sometimes it may even be very late April. Because of the extreme winter cold and wind we get in Nebraska, much of the more tender, upper canes will die and turn brown. Anything dead, prune it off. In late April it is easy to see what is dead because anything alive will show swollen buds. Everything dead above the last swollen bud can be removed regardless of the group. The easiest way to prune a clematis is to stand up next to it and anything above your waist, cut it off. If you follow this procedure and your clematis blooms on old wood, you are leaving a lot of old wood and will see a spectacular bloom from the height of your waist to the ground. This works equally well for clematis that bloom on new wood. Plenty of new growth will present before fall so that you will get a spectacular bloom from new vines. If you want your clematis to grow over the top of an arbor or 12 feet up a tree you probably will need to buy a group 3 clematis like Sweet Autumn. A large flowering clematis just will not survive our winters above 6 feet in height. In twenty five years I have not seen a Jackmanii blooming on top of anybodys garage because the highest parts of the vine don't survive our winter cold and wind.
Anything higher than your waist, trim it off. Enough about pruning.
Pruning is important but so is shading the root of a clematis. Shade it with a heavy layer of wood chips, slant a shake shingle over it or build a box to place around its base. If you shade with a structure of some sort, be careful you don't create a winter habitat for rabbits or worse yet, hundreds of mice. They can do massive damage to the base of a clematis and if they get really hungry you won't have to worry at all about pruning in the spring because the rabbits will do it for you. Truly, a five inch layer of wood mulch is probably the best way to shade the root of a clematis. Be somewhat careful of grass clippings because as they decompose you may see some fungus problems, expecially if it stays really wet.
Fertilizing: You can fertilize your clematis real early in the spring and once right after the first flush of flowers have faded. Mix the fertilizer half of what the label recommends. If you have planted in good soil you won't need to fertilize much. Clematis are very prone to problems when salt levels build up in the soil. If your, or the neighbors dog urinates on a young clematis once it may have a chance, twice and it is dead.
If your husband weed wacks a little too close to that newly planted clematis and cuts it off, tell him he killed it and try to get him to take you out for supper to make up for it. Don't tell him that it will really be just fine. They will regrow from the root and be even fuller, stronger, and nicer in the future. He simply did the first pruning, by accident, that most gals just refuse to do. It will be late flowering, possibly by 11 months but it will be OK.
Last but not least is the dreaded clematis wilt. The new hybrids are more resistant to clematis wilt but it has definitely not been eleminated. If your clematis comes up and looks excellent in April, early May, and maybe into the first week of June and three days later you walk by it and it is brown and looks completely dead it probably has the wilt. You can try to salvage it by carefully removing everthing that is dead and dispose of infected vines in a trash can. Be careful not to nick or slice into healthy canes. New canes will replace the old and may perform well for a few years. I have a Jackmanii at my home that has the chronic wilt. It never kills the root system, just levels the vine every June. The canes all die back and new ones come on but they never have time to produce blooms before it freezes. I haven't seen it bloom in 8 years, while the two that are planted 10 feet to either side of it are beautiful every year. Best advice is dig it out, discard it, and start with a new one.
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