Box Plant Leaves

Martin105 · October 2020

I had noticed over the summer, that a few leaves on my Box plants were showing a browny, rusty tinge. This seemed to be mostly in the centre of the leaf. No leaf has been totally affected as yet, and could not find similar known issues online.
This has progressed over the summer, and although it is not looking disastrous yet, I am concerned that it may get worse. These are growing in containers, and have been issue free for several years. Is this something that I can clip out next spring or does it need more urgent attention.
I have uploaded a few images

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Borderline · October 2020

Container growing for shrubs can be challenging in general. With harsh pruning, and often potted into small containers because they looks more pleasing, it means you need to make sure the plants are watered regularly. Rain will not be sufficient, especially during the growing season. Always water generously and not a light sprinkle around the base, otherwise water will not wet parts of the soil evenly.

Pale colouring and tinges of bronze indicate stress either from cold or very likely your shrubs need feeding. Liquid feed will be more suitable for Box shrubs. They can be demanding grown in a container.

Finally, consider re-potting to a larger size container. Your plant could be pot bound now. Always use a loam-based compost like John Innes No 3 with some added grit and a top dress of compost or composted bark.

Fairygirl · October 2020

I'd say that's completely normal. All evergreen plants drop foliage, change colour etc, as conditions and seasons change.

Wind, cold and drought are the most common causes of discolouration though.
As @Borderline says - with pots, it's important to make sure the soil is refreshed each year and adequate food and water are given. Box does best with adequate moisture and a bit of shade, so if it's sunny and dry, they're more likely to need a little help

Martin105 · October 2020

Thanks Borderline and Fairygirl for your response. I do agree that they do need re-potting, but regards feeding, they had been getting a liquid tomato feed every 2 or 3 weeks. Also a fresh top dressing applied early Spring, so I don't think feeding was to blame.
I am presuming that even if I provide optimum conditions, the present leaf discoloration will remain, so should I therefore prune(clip) the plant or is that a waste of time.

The location of the plants has them in more shade than sunlight. Even at the height of summer, they may not get much more than 4 or 5 hours sunlight. Not sure if this is contributing to the plants problems.

But as Borderline points out, a re-potting is definitely a must. That can wait until Spring
Now, do I pot on to the next size up, or should I go for a much larger container and skip a few years potting on ?

Appreciate all your input..

Loxley · October 2020

Tomato food is probably not the best for regular fertilising of box - it's high phosphorous, and the box doesn't need that much phosphorous since you don't grow it for flowers or fruit. Too much phosphorous can cause iron deficiency (causing leaf discolouration), and it builds up in the soil. I would repot in fresh compost (shake off as much of the old as poss) in slightly larger containers, and stick to a balanced foliar feed designed for evergreen shrubs (it will be high in nitrogen). There are a few specially formulated for box in fact. Better to be sparing with fertilisers in general, and rely more on repotting in fresh compost.

Fairygirl · October 2020

Agree totally @Loxley. Tomato food is no use, and that may have been a contributing factor.
Seaweed is ideal for any foliage plants- readily available in liquid form, which you just dilute.

Box Plant Leaves

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