An Arborist’s Approach to Yamadori

Collecting & Aftercare

Conifer Collecting

My concepts of collecting and caring for Yamadori conifers are contrary to beliefs or teachings of many bonsai enthusiasts. What I have learned and applied over the years with Yamadori is rooted in my Arborist and Horticultural trainings.

When to Collect

As with anything in our busy lives the best time to collect is whenever you can. Spring just before bud break is the best time but due to snow, climate and accessibility there is a limited window of opportunity available. The second best time, or in actuality the best time is in summer to l fall for conifers, especially during a drought or heat wave.  What to look for before collecting at this time of year is that all new growth has stopped and next year’s buds have hardened off. During the latter part of summer during a dry hot period most conifers go into ‘summer dormancy’ or better termed as quiescence . Growth has been completed there is new foliage, roots and the buds are already set for next spring’s flush. The next stage for tree growth is trunk growth but we are going to divert this trunk growth energy into root growth at this time of year. Since conifers exist  in seasonal environments they must  adapt to the conditions presented by both favorable and unfavorable seasons.dormancy reduces  exposure to seasonally stressful periods and is basically evading stress, dormant plants do not grow or reproduce. Stress evasion during a drought or a shortage of moisture, tree defenses act in. There is a reduction in transpiration, respiration and photosynthesis. This enables the tree to conserve for next year’s growth, for without growth a tree will perish.  When digging out our selected yamadori it is critical that the top two inches of soil within the drip line is not disturbed, this is where all the fine feeder roots reside these are the roots that sustain the tree. All the larger tap and striker roots can be removed. Once dug I bring along a roll of shrink wrap and shrink wrap all the soil and roots nice and tight.

Yamadori Care

What happens next is critical for 100% success; the yamadori is in quiescence and will respond to a change in environment. I do not use ‘coffin boxes’ known as grow boxes, in the ground or pots at this stage.

A layer of good ground or landscape cloth that allows air and moisture to penetrate is placed on top of the ground in a shade area away from hot afternoon sun.Add 2 to 3 inches of a well rotted mulch, compost on top of the cloth, what I have available commercially is a fish composted fir mulch. Well rotted compost contains humic acid, aerobic bacteria, retains moisture, retains heat and has pore space. Good compost will show NPK (nitrogen, phosphate, potassium) values of 1-1-1 and will usually be constant  at 1-1-1  NPK, due to the activities of the aerobic bacteria until there is no compost left.in a form that is available for tree roots. All of this contributes to induce root growth which is want we want. A good idea is to mound up the compost and center the yamadori over the mound and rub in. Cover the Yamadori’s root base with at least two inches of compost not more and do not make a trunk volcano out of the compost, use props and stakes if needed to prevent movement of the collected tree.

The tree is above ground, there is great drainage, plenty of room for root growth, no large air spaces in the root pads, no unnecessary cutting of roots to fit a coffin box or pot. No potential root damage to the lack of oxygen that may occur with in the ground trees. Potting up after the Yamadori is established is much quicker, easier and also during the recovery time a certain amount of surface root work can be accomplished because you can get at it. Water and mist daily, a limited amount of fertilizer can also be added at this time.

There should be enough stored resources in the tree to promote a small amount of root recovery in the form of renewed root growth. Root growth usually occurs in the spring and coincides with shoot growth but since we have provided the collected yamadori with a new unstressed environment new feeder roots will grow into the mulch medium that we have provided thus ending the summer quiescence.

 

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4 thoughts on “An Arborist’s Approach to Yamadori

  1. Hi Anton,
    Your analogy aligns itself with the life cycle of most conifers. Some further clarification from my world….an article I’ve recently read in regards to summer planting of forestry seedlings. The dormancy period is broken into quiescence and rest dormancy.
    Quiescent (earlier stages of dormancy) conifers if well irrigated or moved to a greenhouse where a favorable growth regime is maintained will break its bud and resume active shoot elongation (we get this a lot during some summers = Lammas growth). In contrast, a conifer in “rest” will not grow regardless of how favorable the environment is.
    I also think there is a longer period of yamadori collection in late summer whereas the spring window is rather short.
    Cheers
    Graham

  2. Hi Anton,
    Read your article about Yamadori Conifer with great interest. I’ve got 2 Garden Conifers which I am considering to cut back and make into Bonsai.It would have been great if you had Photo’s to accompany your instructions!
    Kind regards Jim

  3. I collected a fabulous western white pine yesterday mid September. Is there any difference where location is concerned? I live inland San Diego, fairly dry and mild winters.

    By the way great post I love science based bonsai. Understanding the reasons behind the diffdrent techniques.
    Thanks

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