Japanese Black Pine Pinus thunbergii

Pinus thunbergii before needle thinning

Removing needles can be as important as pruning branches, in order to stimulate back-budding and develop branch structure. As with most evergreen conifers the normal approach is to cut back to something green but if there isn’t anything growing lower down a branch, what do you do? A fellow club member asked me to look at his Japanese black pine (Pinus thunbergii) at a recent show as he was concerned about this.

The majority of needle thinning should normally be done from autumn to early spring, or before any repotting takes place. I like and use Jake Hobson’s reminder and try to get all mine done before the new year (in the time of dormancy). Needle plucking provides these benefits:

  • Balances vigour and energy distribution
  • Improves aeration and light dispensation
  • With both the above in turn; increases back budding therefore growth, density, ramification and health.
Japanese Black Pine Pinus thunbergii

Last year’s needles removed

So first up in this instance, all last year’s needles were removed. I use a long pair of tweezers to minimise the damage to the rest of the foliage and tree.

Japanese Black Pine Pinus thunbergii

This year’s needles reduced

I then reduced the number of this year’s needles to the following recipe

strong areas leave four to five pairs of needles*
medium areas leave seven to eight pairs of needles
weak areas leave all needles

*on more mature trees, it may be necessary to remove more needles in the strong areas only. This could be as few as three pairs of needles.

It is important when undertaking this process to remove the needle’s sheath and any other remnants that will provide somewhere warm and sheltered for pests to harbour and over-winter.

This works well on Japanese Black Pine which is a two-needled pine, this technique may not work on other species of pine in quite the same way. The reason it works so well is because black pine is extremely vigorous.