New Root Over Rock Tridents

Today I dug the trident Root Over Rock plantings out of the growing beds. Growth this year was far below expectations because of the extremely hot, dry summer we have just had but mot of these have turned out quite well. These have had just 1 year in the ground.You can read my method for starting root over rock plants elsewhere in the blog.Digging and unwrapping these is a lot like unwrapping presents – you never know what you are going to get. Here are a few photos….

Root over rock tridents in the grow bed


Ready to unwrap.......


roots cut and top pruned


The good ones potted up


2 thoughts on “New Root Over Rock Tridents

  1. Hi Neil
    I take it from your pictures of the unveiling of the roots that the potting up phase doesn’t involve any further use of foil below the surface. Or, asked another way, is the attaching or moulding of the roots to the rock an ongoing process that is set in the right direction with the foil below the surface for a year and then completed over subsequent years of growth of the tree with the roots exposed ?.
    Also, do you have any advice for other species – for example the duration of the foil phase.

    • Your supposition is correct Mike. When the tree/rock/root combination is judged ready all the foil is removed and the tree potted up at its final level. By this stage the roots should be closely attached to the rock. You could continue with foil wrapping if the roots are not large enough or have not yet grown closely against the rock. Several of this year’s batch were rewrapped and put back in to continue development. Once the roots are moulded to the contours of the rock by the first few years wrapped in foil they will usually stay close to the rock. as they thicken much of the growth will be sideways and they will start to flatten against the rock surface.It could be beneficial to keep the roots wrapped and buried for a few more years in an attempt to enhance the roots spreading (thickening?)sideways over the rock surface but I have not done that. I think it would be difficult to start developing appropriate branches on the trunk if you cannot see the shape of the rock and roots.
      Most of the specimens I grow are medium and small so a couple of years is enough. More time in the ground and the trees get too large for the rocks and look unbalanced. If you are using larger rocks or slower growing trees maybe a further year or 2 would be appropriate.
      I have tried this with Acer palmatum and Pinus thunbergii. Roots of both these develop far slower than trident maple so they have had to remain wrapped for longer for the roots to develop enough – 3 -5 years instead of just 2. Note that alfoil begins to break down in the soil. I have been replacing foil annually to stop roots escaping through weak places in decaying foil.

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