Long Caned Dendrobiums

I’m sometimes asked how I grow the long caned Dendrobium species, plants like Dendrobium aphyllum (syn. pierardii), Dendrobium anosmum and Dendrobium lituiflorum. These plants are capable of growing in excess of 3 feet (c. 1m) in length, often to 4 feet (1.2 metres) or more. Thankfully, they all begin to flower as much shorter plants, as short as 12″ (30cm.). Their height can be kept relatively short by culture where space dictates, but they are best grown to their full potential.

Normally, plants for sale are usually in the 12″ to 24″ (30cm. – 60cm.) height range so we can decide from the outset how to grow the plant. There are many ways they can be grown. One method is to grow them in a pot with a bark and moss mix, training the canes upward on a bamboo frame; it works very well for people. Another way is to grow them on a cork bark mount, or in fact a piece of branch allowing the canes to grow pendulously from the mount, but, often the canes won’t grow downwards, or they may start growing upwards then arch over with their own weight. Some people grow them in net baskets or wood baskets which they pack with moss during the growing season. Initially they are grown upwards with the basket the right way up, and then when they are given their winter rest the plant is turned upside down and hung in the greenhouse until they flower, then turning them the other way up again for the growing season.

I prefer to mount my plants on bark or on a branch and try and achieve a more natural effect. It’s probably better to start off in what I call spring in my greenhouse, which bears no resemblance to spring outside. On or just after the shortest day, around the 21st December, I move them into my warmer greenhouse which is set to keep temperatures to around 12c – 13c at night, the greenhouse they are moved from is around 8c but on very cold nights it can drop to 5c or 6c but usually not for longer than a day or two. After a few weeks in the warmer house, probably around early February, the young growths begin to appear at the base of last year’s canes, the exception to this is Dendrobium chrysanthum which actually starts its new growth a week or two after flowering in the summer, it usually flowers around June or July and the growth starts in August. This is my experience with it anyway. With the other long caned Dendrobiums it is important not to start watering yet as the new growths are likely to damp-off and waiting on other new growths will lose valuable growing time. Once the new growths reach a couple of inches in length (about 5cm or 6cm) close inspection of the previous year’s canes should hopefully show the flower buds pushing through at the leafless nodes of the canes. At this point it is probably safe to assume they are flower buds, but some may be keikis – keiki is Hawaiian for “baby” or “child” and is a small plant which develops asexually and is a clone of the parent plant – but the plant has probably already decided which of the two they are going to be. Once the new growths are established and the plant is producing new roots watering can commence, but it is important to start with increasing the spraying of water on the plant’s roots beginning early morning and doing so several times per day. Over the course of a week or two, increase spraying until the root system is being thoroughly soaked then full watering can start. As the buds develop, try and not spray the buds or flowers with water as they might abort, especially if they go into the cooler night with water on them.

By early March through to late May it is hoped that all your efforts have produced flowers and lovely scents, the flowering period will depend on each species. This, however, isn’t where our work stops; we still have to prepare the plants for next year’s flowers. Once we have enjoyed the flowers we need to turn our attentions to those new growths that started back in February. Hopefully they have continued to lengthen; it is now our task to ensure that they achieve sufficient length to flower the next year. It’s quite possible that some of those original buds weren’t flower buds, but keiki buds; they should be getting into growth as well. Some people wait until these keikis form their own root systems then they remove them to grow on as individual plants for swapping with friends, while it may be nice to do this, I don’t encourage it; let those keikis stay on the plant. Eventually they will flower themselves enhancing the number of flowers in spring. Eventually, when that cane begins to shrivel and offer no sustenance to the plant the keikis can then be removed along with the shrivelled cane then grown on as a separate plant and given away, kept or swapped. But, back to our main plant, if it is in a pot, make sure the pot gets a thorough soak, depending on weather this could be every other day, but it’s important that the compost is allowed to dry out before watering again otherwise roots can rot. This is one reason I prefer my plants on a mount, you can see exactly what is going on, most of the time, but at least you can control what is happening better. Mounted plants get their root system well covered by a large piece of Sphagnum moss. This helps with ensuring the plants get as much water at the roots as possible, you can also tell more accurately when the roots become dry and are ready for watering again. Next, we have to offer plenty of nutrients get those long lengths of canes. I like to keep this simple. I’m not a great believer in giving reverse osmosis water which is then given a scientifically measured amount of fertiliser, it just seems to clinical to me. I make my my own liquid fertiliser from farmyard manure and keep it in a large dustbin in the greenhouse, it holds around 40 gallons (c. 180 litres). Once per week I put the root system on it’s mount into the bucket of liquid manure and allow it to oak for around 10 minutes, then I hang it up again. This is in fact how I feed all my orchids, those grown on mounts.

In the height of summer, water is increased as well as shading, fertilising is also increased to about twice per week. Air circulation is also increased to reduce the possibility of mould and bacterial disease, this is always crucial in any orchid house with high humidity. as summer progresses we are hopefully putting on a good length of cane, but what is a good length? You may ask. Probably it is best to hope that we end up with a cane length of 1″ or 2″ (2.5cm – 5cm) longer than the previous year, and preferably not less than the previous year. Depending on where you bought your plant, you are never going to get the conditions that it was used to, no matter how hard you try. This change of conditions can often mean that due to settling in it won’t put on a cane as long as previously, so we won’t over worry about this. Aim to get improvements the next growing year. If you purchase a plant of around 12″ (30cm) then you should be looking at increasing the cane length by the amount previously mentioned, it is a relatively young plant, so annual increase should be possible. If in the second year you aren’t matching the previous year’s length then you need to look at where you can improve your culture, is it water, feeding, humidity, etc.

As we reach the end of August the canes should be near completion, you can check the blog entry “Is My Dendrobium Cane Completed” for guidance on this. As the new cane completes, fertilising is stopped and water is gradually reduced over the next few weeks until the plants are only receiving a misting with water perhaps twice a day. I place the plants in the cool house at the end of August where they remain until the cycle starts again in in December. Some years you may find that canes don’t complete until perhaps late September or early October, it is important to keep them growing until they do otherwise the canes won’t mature properly and they can start to die back for several inches in the winter. Just keep them growing until they complete, this may involve missing the cool period.

As previously mentioned, I find that Dendrobium chrysanthum starts it’s growth in August, because of this I don’t give it a cool rest but keep it growing, although slowly, through the winter and spring into summer. The plant flowers in June or July while still in full leaf, the others are deciduous and drop there leaves in early to late autumn, but D. chrysanthum sheds it’s leaves after the new growth is well underway in October. While I always enjoy and encourage feedback, remember that this is how I grow them and this method works for me. If you do something different, then I encourage you to write, perhaps what you do different may be beneficial to someone else.

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