Answer: Pyracantha can make a good candidate for espalier (actually it is related to the apple which makes a great espalier), but usually the training is best started very early, at planting time. Here are step by step directions to show you how it would be done. There are also some tips at the bottom of the page which should be very helpful to you as you go along with the project. You may need to cut and paste the complete url into your browser to make it work correctly.
Since you have an established plant, use the above as a general guide to the basic structure you need to try to achieve, then work with the existing plant as best you can to develop something similar. You will probably need to do some substantial thinning, so take your time and spread it out over several years to select and refine the branch structure. Heavy pruning will actually stimulate denser growth, so be sure to keep after it regularly to keep new growth in bounds. Espalier is not a low maintenance plant, so be sure you are ready to follow through with the constant pruning.
Pyracantha cuttings root best in the semi-hardwood stage (mid July to early fall), so time of year makes a huge difference to your success rate. Here are some more detailed instructions on how to do this, to help you review your technique.
Good luck with your project!
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