Pruning

    This section deals with the pruning of clematis, most other vines fall into a group 1 pruning regimen.  Indeed the pruning of clematis has been made more complicated than it needs to be.  

    There are 3 clematis pruning groups.  The group numbers (1,2,3)  correspond sequentially to their main blooming period within the year.  Group 1 blooms in Early Spring, Group 2 in Late Spring, Group 3 in Summer.  There are but a few exceptions to this.  Some varieties will have repeat blooms later in the year as well.  Some people will try to make 4 pruning groups, splitting group 2 into 2a and 2b.  However, I agree with Jim Fox , a noted horticulturalist from the Seattle area, that we would do just fine with just 2 pruning groups.   Some you prune lightly some you prune hard.

    Before getting into the specifics you should relax.  If you never prune a clematis it will grow. It may not look it's best or it may produce flowers at a height  where you won't get to enjoy the flowers - but it will grow.  So pruning is foremost a way to get the vine to make flowers down where you can enjoy them.  Pruning will also encourage low branching and therefore a fuller look.  You may find you want to prune to remove excessive foliage  and to shape the plant to whatever support structure you may have.  

    If you have a clematis that hasn't been pruned in many years, you should skip down below to remedial pruning. 

    Lets begin...

Group 1

     Group l clematis bloom in early spring on growth from the previous season.  Pruning should be done in spring after blooming or during winter.  Hard (heavy) pruning should be done after blooming in late spring.  This allows the plant to recover and set flower buds in the late summer/fall for a good show in the following spring

Late Spring pruning- is best done to shape or control the plants growth. 

Winter pruning - Remove any dead or weak stems and trim each stem above a strong pair of buds.  Which pair of buds is up to you and where you want next years growth to start.  A hard winter pruning may have an adverse effect on the amount of flowers for the following spring.  Don't overdue your concern about pruning exactly perfect you will get another chance for any improvements next year. 

If you are starting with a new plant-  In winters of years 1 and 2 trim each stem above the lowest pair of active buds.  This will encourage the plant to branch low and be more bushy.  In year 3 and after trim to remove dead or weak branches and to shape the plant. 

    I trim my montana 'Pink Perfection' during winter.  Here you can see some tip die back (brown portion on right).  I have chosen to trim back to right above a strong pair of buds.  The stem has better diameter and both buds look healthy.

Group 2

  A group 2 clematis blooms on growth from both the previous season and the current season. The blooms from the previous seasons growth are often desirable so pruning this category of plants is different than the groups 1 and 3.  The blooms from the previous seasons growth can be double, semi-double or single.  Blooms on current seasons growth can also be double, semi-double, or single.  It depends on the variety as to what kind of flowers you get and when.   Pruning is best done in late winter after there is some bud swell.  Starting at the ends of each stem, trim each one back just above the first pair of active buds.

If you are starting with a new plant- Prune in late winter once the buds have swelled a little, this way you can tell if they are active.  During the winters of year 1 and 2, trim each stem above the lowest pair of active buds.  This will encourage the plant to branch low and be more bushy.  In year 3 and after trim each stem back above a strong pair of buds.  

Companion plant pruning-  If you are using a group 2 clematis as a companion plant they can be trimmed down to 12-18" each winter.  You will sacrifice some or all of the earliest flowers by doing so but you will get the blooms that occur on the current seasons growth.

Here is an example of trimming above a strong pair of buds.

Group 3

    This is perhaps the easiest group.  It blooms on current season's growth every year.  Pruning is quite simple, cut every year down to 12-18 inches above the soil.  Pictured is clematis 'The President' (group 3).  It gets the same level of pruning every year. 

    My father had c. 'The President' (Group 3) in his yard and he decided to not prune it one year.  It continued to grow onto his roof and this is where it bloomed....on the roof!  Later he did some remedial pruning and everything was fine.  When this clematis was about 15 yrs old it came out of the soil a full 12" in diameter, and really put on a show.  'The President' is a well known classic for all the right reasons- easy to grow, blooms during summer when you are outside the most, and has dark green heart shaped foliage.

Remedial Pruning

So you have a neglected clematis...bushy, tangled, laying on the lawn, blooming on your roof,  what do you do? 

    Start by cutting 1/3 of the stems at 12"- 18" from the ground during the winter.  Trim the tops of the remaining 2/3 as recommended for that group unless it is a group 3 which I would prune lightly until you get the base back in shape. When the original 1/3 has new growth appearing cut another 1/3, and then the final 1/3.  Wait a year between cutting 1/3's and trim only if you get new growth from the previous years pruning.  After getting each "1/3" of the clematis back down to low strong braches prune as recommended in the above groups. 

WARNING!- Evergreen clematis armandi may or may not take such heavy pruning and survive.  Try cutting some stems down but leaving several sets of leaves and wait and see if you can get some adventitious bud growth from the base.  Often this is all it takes to get some foliage to cover those bare lower stems.

Breaking "the rules" pruning

    Oh the Blasphemy!  Toss all this tradition out the window?  Well...yes.  We have an old variety named Margaret Hunt  (summer blooming - group 3) on our back deck.  My wife trims this plant in layers - roughly 1/3 of the canes she trims at 18", another 1/3 at 36" and the final 1/3 at @ 5'.  As you can imagine this covers the plant from top to bottom with fresh growth (i.e.  no low bare stems) and because it is a group 3 it also covers the whole plant with flowers.  Why do this you ask ? Our deck is 3 feet off the ground and this will cover a larger area and higher up than it would if you cut it all at a short 18" recommended height.  You could use this method to cover entry or garage doors, or anywhere you want to spread the flowers out.  

Easy to remember pruning jingle...

If it blooms before June - Don't prune!

(i.e. prune lightly)