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Horticulture/Pruning a shrub into a tree

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Question
We had what looked like a hydrangea, except it was a tree, not a shrub. I've been told that it was probably a Hydrangea paniculata 'Grandiflora' shrub that was trained into a tree form. Very pretty, with flowers that changed color as they aged.

We had to take down the tree because it was blocking access, but I would like to have another "hydrangea tree" in a better location. Fortunately, each year the stump sends up lots of shoots that I can use for air-layering or cuttings.

What I haven't figured out is how to get a shrub into tree form.

I air-layered one shoot and pruned off the side growth. While the new roots were developing, the main stem kept growing straight up. The air-layering took, but the stem was too thin for such a tall plant and it snapped in the first strong wind.

Next time, I pruned off the side growth and when it got tall, I cut off the tip. But two new shoots emerged below the cut and now the plant has a rather ugly V shape.

What is the right way to get a single, strong trunk? Should I leave the side growth on for a few years?

Answer
Hi Janet,

It's going to take several prunings to get a stem thick enough to hold up all that weight.  Also, applying a complete fertilizer midway through the growing season (8-8-8, or 13-13-13) will help.  Don't, however, apply nitrogen too late in the fall, because that will cause rapid, spindly growth.

Here is a link to give you some tips - it includes another link to a video.

http://www.viette.com/v.php?pg=615

Thanks,
Susan

Horticulture

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Susan Tabor

Expertise

Entomology,plant pathology, agronomy, native plants, useful and edible plants,medicinal plants,landscape design and installation, plant taxonomy and identification, cultivars and varieties, Botany, nutrient deficiencies, plant recommendations and troubleshooting.

Experience

35 years as a professional horticulturist and landscape contractor. I have a network of contacts at leading universities and with acknowledged experts in the field. I've restored the landscapes of several plantations, 2 Governors mansions and owned/managed 3 nursery/garden centers. I discovered a new subspecies of Emelia in 1997. I've locally introduced several native or volunteer species into mainstream landscape design.

Publications
Morning Advocate The Register Better Homes and Gardens All Experts - Approx 1996-97

Education/Credentials
Louisiana State University - horticulture David L. Hoffman - California - phytotheraphy

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