Question
Dear Jim,  Please could you shed some light on a problem we are having with our two large Hollywood Junipers.

We planted them 4 years ago when they were 6ft tall they have grown to about 9ft now and have always been the picture of health until the last few weeks when they have turned brown inside.

I know conifers do this and we have two Green Giant Thujas that turn brown inside, but this is the first time these junipers have turned brown inside. We have checked for red spider, bagworms, webworms, juniper midge, tip blight, dogs urinating and mice, but it is none of those things. The insects we saw round them and on them were ants, small brown flying insects and small black spiders, but not a lot of any of them.

The other two things I read it could be is too much or too little water. So since it hasn't rained for a week or so I went  and gave them a good watering. They don't get too much water, they are on a slope and the water drains away very well. But I have not watered them as much as I did for the first two or three years since I read that when they are established they don't need much water.

Have you any advice please?

Answer
It sounds like normal needles drop. The loss of older interior needles in the fall is a natural process, which is often confused with injury, disease or insects. This process usually goes unnoticed since the needles on the inside of the conifer are concealed by the foliage on the exterior of the tree. Leaf drop on evergreens usually takes place gradually, but there are occasions when many leaves will discolor simultaneously, and the tree or shrub may appear to be dying.

The foliage throughout the interior portion of conifers turns yellow, then brown, and finally drops off. Entire bundles of pine needles will shed. Cedars (Thuja spp.) and some junipers have scale-like leaves covering branchlets instead of needles. Entire branchlets are dropped instead of single needles. The oldest, or innermost, needles of spruce and fir shed first; however, needle drop is not always restricted to the oldest needles.

Any factors that increase stress on evergreens will intensify autumn needle drop. Weather factors like too little rain or too much can speedup this process and increase its intensity.

As long as the outer foliage is green and healthy looking everything is ok. You may want to think about pruning next spring.  Because of their dense foliage, junipers require little pruning to maintain their shape. However, if you feel you must prune, there are a few delicate rules to follow. Not pruning a juniper the correct way can lead to bare spots, uneven shape and disease.

Here is some guidance:


Look at your juniper for pruning needs in early spring just before the new growth begins; early spring is the best time to prune junipers. Start pruning and shaping while the tree is young and do a small amount each year.

Identify areas you would like to prune back and mark with ribbon individual branches to be cut.

Identify the "dead zone" of your juniper -- the inside of the plant that is full of bare branches and wood. Never cut back to this dead zone or wood that has no needles on it, as junipers will not produce new growth on this type of wood.

Cut individual branches back to a side shoot or leaf of an upward-growing branch, using pruning shears. Cutting to this type of shoot will make the tree look younger and healthier while maintaining a pleasant shape.

Cut any completely dead or broken branches back to the main trunk using loppers, as the juniper is wasting energy on these branches that could be better used to promote new growth and keep the remaining branches healthy.

Avoid cutting your bottom branches shorter than those above them, as tapering in towards the bottom creates too much shade and thus will kill off the bottom. Make sure the base of the juniper is wider than the top.