This Goldflame Japanese Spirea (Spiraea japonica ‘Goldflame’) was originally dug from a garden in the UK. It was styled by Harry Harrington. You can view it and numerous other noteworthy bonsai at bonsai4me.com.
One reason we’ve been featuring field growing so much is that the US government restrictions make importing quality stock from Asia somewhere between difficult and impossible (Europe is a whole other story – it’s easy for them to import Asian stock – which helps explain some of the differences between European and North American bonsai). This means that if we are going to develop quality bonsai stock in this country, we need to learn how to grow our own.
One of my favorite bonsai sites, bonsai4me.com is from the UK (a great place to grow most temperate zone plants). The following text and the photos above are from this site.
Field Growing Trees For Bonsai
A common misconception amongst newcomers to the art of bonsai is that trees (bonsai) with large, thick trunks must have had decades of training to become the size they are and that a thin-trunked seedling will one day acquire a thick mature trunk even though it is planted in a bonsai pot.
Unfortunately, once a tree is growing in the confines of a small pot, with its roots restricted and upper growth regularly pruned, the trunk and branches of the tree will only thicken very slowly.
Large bonsai with thick trunks are nearly always developed in the ground prior to being planted into a pot; some are purposely field grown, some are collected mature trees.
As a tree develops new growth during the growing season, it lays down new wood to feed and supply its new shoots and leaves. The more new shoots and foliage the tree produces, the more new wood is developed to support this new growth. This new wood grows around the outer ring of the trunk and branches in an almost direct passage from the new shoots, back through the trunk to the root system, gradually increasing the trunk’s diameter. Therefore, the greater the amount of new growth a tree achieves in a season, the greater the increase in the girth of its trunk.
A tree that is allowed unrestricted growth will always thicken faster than a tree that is pruned.
The best way to promote unrestricted growth in any tree or shrub is to plant it into the ground; a large container is an alternative but not equivalent to growing in the ground. (This is chiefly due to the difference in dynamics of soil held within a container and that of a large mass of ground-soil; be wary of planting trees in overly large containers, this can in fact slow growth. See Overpotting).
Field-growing techniques can be used within any area of ground, if an area of land is unavailable to you (as is often the case) trees can be grown on (and enjoyed) in the garden amongst ordinary garden schemes, as ‘temporary’ 5-10 year hedges or as ‘temporary’ garden specimens. It is also possible with a little work to build raised beds specifically for the purpose of field growing; raised beds can be walled with brick or wooden planks and filled with good quality soil.
Any tree/shrub species can be used for field growing as long as it is hardy in your local climate. Native species naturally thrive in your local climate and will therefore respond to give the best results; other species will develop well but can take longer to establish in the ground before growing with real vigour.
Any age or size of tree is suitable for field growing as long as it is well developed enough to compete with any grasses or weeds that might compete for light or moisture. Generally, cuttings, seedlings or saplings should be at least 2 years old before planting out unless you are able to cosset them for the first year.
For more go to Field Growing Trees For Bonsai