Should I fertilize my decandled pines in summer?

To determine if a decandled pine needs fertilizer in summer, I check to see how the summer buds look. If they’re strong, I hold off on the fertilizer until later in the growing season (usually September or October). If the buds are modest or small, I consider whether or not the pine looks good in fall.

If the length of the needles that grow over summer is usually appropriate for the tree, I’ll want until later in the season before fertilizing. If the needles are typically small, I’ll start applying fertilizer.

Here are some examples.

The buds on the pine below are small. The needles that develop over summer are consistently smaller than I’d like. I’ll fertilize this tree over summer.

Small buds

The buds on the next tree are large so I’ll hold off on fertilizing until later in the season.

Vigorous summer growth

The tree below is in early stages of development. Unsurprisingly, the new shoots are large and plentiful.

If I’m trying to build vigor and I want a strong budding response, I’ll fertilize through summer. If I have all of the buds I need and I simply want to increase branch density, I’ll hold off on the fertilizer for a month or two (in this case, I’ll hold off on the fertilizer).

Vigorous new shoots

The pine below is more developed and the new buds are small. Although the tree is also small, the summer needles tend to be shorter than I’d like. This year I’ll fertilize through summer.

Relatively small buds

I tend to keep fertilizer on weak trees that I’ve decandled or partially decandled, on trees that have been repotted, or on tiny trees that don’t have the same reserves as larger trees.

Mini pine

Unless a tree is overly vigorous, I’ll plan to fertilize all of my pines for at least one or two months before the trees slow down for winter towards the end of the year.

News & Updates

• The Redwood Empire Bonsai Society’s 37th annual show is coming up next month on August 26-27th in Rohnert Park, California. A quality exhibit, large vendor hall, and headline demonstration by Ryan Neil will welcome guests to the new location at the (air-conditioned) Rohnert Park Community Center. Learn more about event at the REBS website.
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