Evaluating summer growth – how much is enough?

One of the most common questions I get this time of year is whether or not the summer growth on decandled pines is strong enough. A better question might be, based on the summer growth to date, is there something I need to do to keep the tree on track?

Here’s a black pine I decandled this spring. The needles are on the short side, but they’re about what I’d expect for this time of year where I live.

Decandled Japanese black pine

Short needles

I decandled the above tree near the beginning of decandling season. Some of the trees I decandled towards the end of the season didn’t come out as strong.

Shohin pine decandled about one month later

The growth on this pine is weak for two reasons. The first, and most important, reason is that the tree wasn’t strong enough to be cut back and decandled to this extent – or at least not decandled so late in the season.

The tree has the right number of buds, but many of these buds are quite weak.

Small shoots

The shoots near the top of the tree are stronger, but the foliage is still juvenile.

Slightly stronger shoots near the apex

The second reason this tree has so little summer growth is that we’ve had fairly cool weather recently. The trees I decandled early this year look great as we had a warm June. Much of July and August, however, were cool. Because the weather cooled down right after decandling my smallest trees, many of them have yet to grow very much.

Until this week. As the weather has warmed up, many pines in my garden are now covered with growth that didn’t appear until 2-3 days ago.

4 year-old pine

New buds

It’s heartening to see this growth. It’s hard to tell, however, what the weather will be like over the next few months so I have no idea what the trees will look like by the end of fall.

Which brings us back to the question of whether or not there’s something we can do to help trees that haven’t progressed much since decandling. The obvious answer is that we can start feeding again, but this comes with the caveat that feeding too early can elongate internodes that we’re trying to keep short by decandling.

I’ll often feed decandled pines with short and/or yellow shoots, especially if the tree is on the large side. I tend to wait before feeding younger trees, smaller trees or trees producing juvenile growth.

I’ll wait a few more weeks before feeding the trees that already have fairly long summer shoots.

13 year-old pine with long summer shoots

Healthy summer shoots

By the end of September I expect to be feeding all of my pines to make sure they go into the dormant season strong and come out well the following spring.