In this instructional video, the presenter walks through the repotting and care of a 40‑year‑old Colorado spruce (Picea pungens) bonsai that originated from seed in 1982. The core message is that coniferous bonsai should be repotted in late summer (July–August in the UK) rather than in spring, because root growth peaks at the end of the season and the trees can recover before autumn frosts. The video details how to inspect the root ball, identify healthy white‑tip roots, and carefully remove the old, dry, sandy substrate and dead feeder roots while preserving the thick, vital root connections. Wooden or bamboo tools are recommended for tactile feedback, avoiding metal hooks that can rip roots. Unlike deciduous bonsai, the presenter advises against cutting conifer roots, trusting the tree to adjust its root mass. After cleaning, the root ball is lightly compressed, backfilled with fresh, well‑aerated substrate, tied in, watered, and fed immediately with a balanced organic slow‑release fertilizer such as Oceana to promote strong root growth. The presenter also explains why spring repotting is risky for conifers and emphasizes finishing repotting by early October to allow recovery before winter. The video concludes with a call to like and subscribe.
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So, um, hello and welcome back to my garden. Now today I've got a Picea pungens, Colorado spruce bonsai, with me. And spruce are quite a popular species, but they're very difficult to grow, and they can suddenly just die back, particularly after repotting. Or wiring and styling. So this particular tree was amazingly started from seed in 1982, so 40 years ago, by a local club member. And I, I was fortunate to buy this offer a few weeks ago. Now, one of the most important things with spruce is when to repot. You don't repot them in the spring. They're far better if they're repotted when they finish growing, which is July in the UK, and repotted in August, which is late summer. Now we don't need to worry about loss of moisture through these, these needles because the transpiration is very low with these modified leaves. And so we can repot in August and the tree is able to react straight away. to any damage and can grow into the new roots, because spruce root growth is strongest at the end of the summer when they finish growing and all their strength is up in the upper branches. Now, this tree I can't style until the tree goes dormant.
So if we take a look at the footage I made 3 weeks ago in early August, you can see that although the tree is nice and strong Its growing conditions are left wanting. The lady who developed the tree from seed absolutely loves the process of propagation and growing trees in containers, but doesn't necessarily worry about planting her trees in good quality ceramic pots or even styling the trees as bonsai. This plastic container has done a good job of keeping the soil well aerated, but is fast falling apart. The soil that the tree is growing in is very dry and sandy and has fallen away from around the roots of the tree in places. I really want to get the tree into a stronger pot and get the risky work of changing the soil done immediately. On inspection of the root ball, I can see that the healthy new roots, identifiable by the white root tips, have been growing around the base of the old container for many years. These are very healthy, and I will go very careful not to interfere with them. unnecessarily, as they almost guarantee the health of the tree if left undisturbed. However, the upper 2/3 of the soil mass consists of something of a dead zone with many old dead feeder roots, and then the thick roots that connect the base of the trunk to the healthy area of the root ball at the base. This is a very typical scenario of coniferous species that have been growing in poor soil for many years, particularly if the soil has become congealed. My task is to carefully remove the old soil from the upper levels of the root ball, breaking old dead feeder roots but protecting the thicker connections to the base of the root ball. Then, with the newly created void, I can literally compress the root ball and backfill where necessary with healthy new substrate. You can see that it takes some effort to open up some areas of the dead root, and it is definitely worth checking to ensure that you are not breaking any live green root. If you do come across fresh healthy roots in the upper area of the soil, stop what you're doing and leave them completely alone. Try to use a wooden implement or a piece of bamboo as this will give much better feedback to your fingers as you open up the soil and old roots. Metal hooks and similar will literally just rip everything apart. Unlike with deciduous and broadleaf trees where I will happily cut back long roots hard, On coniferous species such as spruce, pine, and juniper, I make no effort to cut the roots, and I don't feel that it is necessary to risk the health of the tree by cutting them back or trimming them. Coniferous species will adjust the mass of their live root in the root ball to support the foliage and can be kept pot-bound, often to the advantage of the grower as it will produce better fine growth So the root ball has been cleared as far as I am prepared to interfere with it, and the base of the root ball, where it is very healthy, has been left alone to continue to function as it had been all along. The tree is planted on a shallow layer of fresh soil, tied in, and then backfilled with fresh substrate before being watered. Note that I also feed the tree with a balanced organic slow-release fertilizer. slow-release fertilizer such as Oceana to promote stronger root growth, and I do this immediately at the time of repotting. Although you can repot in spring, it can be nerve-wracking with coniferous species such as pine, juniper, spruce, cypress, yew, and cedar, as things can go wrong and trees can be lost if the roots don't take. Many of us have accepted in the past repotting these species in spring can be risky and simply put losses down to the trees being more difficult. My belief these days is that problems occur after spring repotting because it's just not the best time of year for repotting many coniferous species, whereas repotting in late summer or early autumn seems to be very safe. You can remove more old soil, and the true growth of the tree during the The following year does not seem to be affected. It is important to ensure you repot early enough that the tree has enough time to recover before the cool temperatures and the frosts of the autumn kick in. This means finishing any repotting by early October here in the UK. If you enjoyed this video, please like and subscribe.
