California Native Plant Society

Pruning Tips for California Native Plants

Ted Kipping, Certified Arborist

So, it’s been 5-10 years since you filled up your garden space with a buying spree at your local Native Plant Society Sale. Somehow all those little gallon-sized plants looked rather lonely when you first set them out. Now they have all grown bigger than you could have imagined. It’s time either to remove some (perish the thought!), or to play referee with the pruning tools. What you need are good muscles, sharp clean tools and most importantly, a clear idea of what you want to achieve to attain a vegetative truce in the garden for a year or two.

Your garden vision with proper timing and techniques:

  • Do you want a hedge? Decide whether tightly or informally shaped is right for your plant and space, then use shears or hand pruners, respectively. Make the tops of hedges narrower than the bases or the top growth will shade out the bottom leaving bare twigs and branches and a litter of dead leaves.
  • Do you want an espalier to hide a wall or an unwanted view over the fence? Start tipping back lateral growths to growing leafy nodes close to the plane of desired growth. Do you want a tree or tree-like effect? Gradually trim off the lower growth as it becomes shaded by the upper canopy’s more recent growth. Avoid exposing young thin bark to direct blazing sun. Some light structural thinning will allow for dappled light to reclaim the growing space below, which now becomes the start of your new woodland plantings in part shade.
  • Are you after a “see-through” look from your larger shrubs to tease the eye, create some feeling of mystery and fool the senses into thinking that your gardening domain is vaster and more promising than it seems? Do you want to show off the sexy bark of your Manzanitas? Trim up the lower side shoots, and remove the inner crossing twigs and stems. Remember to step back, have that needed swig of refreshing water, and assess your work for consistency of density and form, not just within the framework of this present specimen, but also within the context of the rest of the garden. Be consistent!
  • Do you want to maintain that Channel Island Snapdragon/Galvezia as a flat and tight irrigation-free ground cover under your Coast Live Oaks but it seems to want to grow into looping arcs like a school of exuberant dolphins? Either trim these back to a ground-flat branch or, better yet, pin them down with “drift pins”– (big wire staples).Other ground-covers can also benefit from a judicious trimming of the mounding branches to thin woody centers encourage lower overall growth.

Species-specific pruning hints:

  • Ceanothus should be trimmed in the dry part of the year. They are very susceptible to Apricot canker if pruned in wet weather Do not leave stubs as these are easily infected.
  • Arctostaphylos also are best pruned in dry weather. Fresh cuts are easily infected by rain splash off of bare soil, so mulch is recommended.
  • Alders are best pruned after August to avoid attracting borers.
  • Junipers and Cypresses are also best pruned in dry weather to reduce more foliage and vascular diseases.
  • Pines are best trimmed between November and October to avoid attracting the numerous species of bark boring/engraving beetles which have recently destroyed so many of our western forests. If your winter is dry, please feel free to provide supplemental irrigation at least to the normal precipitation levels for your locale.
  • Shrubs which bloom on last year’s summer buds such as Mock Orange/Philadelphus or Rubus are best pruned shortly after they finish blooming.
  • Winter deciduous woody plants will be more easily constrained in their growth if pruning is done after the major flush of leafy growth. As a rule, sucker-type growth can be greatly diminished by pruning at this stage also.
  • Oaks in the Black Oak Group, (Coast, interior, and Canyon Live Oaks,, Shreve Oak and Kellogg’s Black Oak) are best pruned in the warmer, drier portion of the year: after the END of spring rains and BEFORE the fall rains begin. Roughly, late May/early June to mid- to late-October. This is to avoid helping the pathogen, Sudden Oak Death, Phytophthora ramora –which seems to infect best in cool wet weather. If you have California Bays close to the above mentioned oaks, you might consider removing the California Bay touching the oak canopies or removing all branches that touch or shade any part of the oak canopies since the wet leaves of the Bays are excellent incubators for the active propagules of one of the reproductive stages of this aggressive organism.

More pruning techniques:

  • KNOW BEFORE YOU GO. Decide what effect you want to create before you pick up your tools.

    TIP BEFORE YOU STRIP. If a size reduction is important, do that first before you crawl inside to remove any inner density. It will save you frustration and embarrassment.

    THE 4 D'S: - What to prune out when uncertaincy strikes:
    • Dead - Always start here. You can’t go wrong and will get oriented to the specimens patterns of growth.
    • Damaged and …..
    • Diseased – Next remove damaged and diseased growth as feasible.
    • Deranged – Remove those branches which cross or rub on another or break the pattern or rhythm of the rest of the structure, such as a weeping branch on an upsweeping shrub or tree or an upsweeping on a weeping form. Branches which do not make it to the outside or especially those which take a long wiggly way to get there require a lot of high maintenance “plumbing” to do the job.
  • THOU SHALT NOT MAKE STUBS. Trim back the target branch to the “collar” or swollen base of the branch, leaving the ring or partial collar belonging to the tissues of the larger limb where it appears to be trying to overgrow the target branch. Do not damage this “collar” as it is the tree’s first line of defense when the branch dies.
  • UNDERCUT HEAVY BRANCHES TO PREVENT RIPS, then make your final cuts. On more massive limbs three or more cuts might be in order.
  • BUY QUALITY TOOLS. Keep them safe, clean & sharp!
  • WEAR GLOVES & EYE PROTECTION, especially when working above your head. If using pole-saws & pole-pruners also wear a hardhat.
  • ON BIG TREES HIRE A CERTIFIED ARBORIST.

Finally, step back to enjoy the fruits of all your labors!

 

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