Cultural Requirements of Hono Hono Orchids
By Scot Mitamura
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The Hono Hono Orchid or Dendrobium anosmum, has been a Hawaiian Favorite for many years. The Hono Hono in Hawaiian refers to the plant's growth habit of alternating leaves, very similar to the introduced and invasive weed, Commelina diffusa. Oddly it's the flowers and their exquisite fragrance and not the leaves that keep people excited about growing this orchid. Another interesting fact about this orchid is that its botanical name, anosmum, actually means scentless! My only guess is that some taxonomist was probably looking at a dried sample, because there is no mistaking the unique fragrance that the Hono Hono has. For this article and simplicity sake, I am including the related species and hybrids of Dendrobium anosmum together, since they share similar cultural requirements.
To grow the Hono Hono orchid well, we must first learn a little about it and where it comes from. Its origin is quite widespread throughout Southeast Asia. This tells us that their dry season is opposite from ours in Hawai'i, therefore we need to manipulate our culture to provide the proper
environment, enabling us to flower the Hono Hono well.
The Hono Hono grow in a broad range of temperatures. In Southeast Asia, they grow from sea level to almost 5,000 ft. in elevation. Hono Honos are very herbaceous (soft stems and leaves vs. woody hard stems like cymbidiums), so their comfortable temperature range will be from the lower 60's to the low 90's. I know they can tolerate temperatures into the low 50's and possibly upper 40's for a short period of time. During their growing season, ideal temperatures would be 70's to 80's. Hono Hono's benefit from a drop in temperatures (upper 50's to 60's) between December and January (dormant season). This in conjunction with a dry period without fertilizer, will help in keeping the plants dormant so that they drop their leaves and “hold back' next year's growth from emerging too early. Often times, if the new growth emerges early, blooming will be poor, due to the fact that the energy is now going to the new growth instead of the flowers. Humidity is also very important and should be kept as high as possible. In fact in the growing season, I don't think you can over water your Hono Honos.
This cycle runs from December to February. Dormancy begins when nighttime temperatures drop and watering is reduced. Keeping the orchids dry during our wet season could be difficult. One way is to move them under cover (polypropylene roof or under the eaves of the house). If the Hono Hono does not go into dormancy, flowering will be poor. Next season's new growth will emerge before the buds and will compete with bud formation.
Decrease watering to two times per week, making sure that the orchids are drying between waterings.
Do not fertilize, tap out any timed released fertilizer from the pots. The Hono Hono Rule: The day that you will eat the most (Thanksgiving Day), is the day that you starve your Hono Hono. It is a good sign when the leaves begin to turn yellow and fall off. The Hono Hono is actually pulling back and is storing all of its energy into plump and bare stems (pseudobulbs).
Buds should begin to form along bare stems. At this time they are very vulnerable to flower thrips, which will turn the small buds brown, resulting in few to no flowers. Next years' shoots will start forming from the base of the flowering cane.
The flowering cycle normally occurs during the months of March to May. Using several different species, hybridizers are making new crosses that bloom at slightly different times. But generally most Hono Hono will flower during this time of year.
The flower buds should become larger and begin flowering. Increase watering to once per day.
Check flowers for unusual markings or crippling. This could be symptoms of virus. These plants need to be culled as there is no cure for viruses. Try to keep water off the flowers, as it will shorten their life. Continue to watch for flower thrips.
This is the best time of year that the Hono Hono should be planted or repotted. As new shoots develop so will the new roots. Planting should be done when the new shoots are 4-5 inches long and the emerging roots are one to two inches long. Avoid damaging the tender root tips. The most common media used with pots is a bark mixture (approximately 3 parts medium orchid bark, 2 parts peat moss and 2 parts perlite). My favorite is New Zealand sphagnum moss. Others like to mount them on Hapu'u (Hawaiian Tree Fern), or onto cork. One caution when mounting is that you really need to water often as they tend to dry a lot quicker.
Continue watering every day or more if possible. Begin fertilizing with a water soluble type of fertilizer.
The new growths emerging from the base of the recently bloomed stems should be about four inches long with new roots forming, before the old stem is removed. Make sure that you sterilize your pruner between plants (a propane torch is best). Viruses are the most deadly disease of Hono Hono and are mostly spread by your pruner. Label cut stems and cut them into 4-5 inch segments. Place them in a shallow tray containing a 50-50 peat moss and #2 perlite mix. Keep them in a shady area and allow the keikis to emerge. Treat the area for slugs as they love to feed on the tender new shoots. Older plants should be repotted every two years. As the media ages, it begins to breakdown. Fertilizing will lower pH levels (becoming overly acidic), and there will be an accumulation of slats. These factors will cause the media to become toxic, causing the root system to fail. Flowering on the third year and beyond, will become less and less.
During this time, the Hono Hono is in its most active growing stage. They are heavy feeders and want abundant water. Grow them in an area of filtered sunlight. Avoid direct midday sunlight, unless you are close to the mountains and have a lot of cloud cover.
Continue watering once per day or more. Fertilize twice a week with a one half strength, balanced,
water soluble fertilizer. Inspect new shoots for thrip damage (browning of the new leaves in the whorl). Also caterpillars can affect the new leaves. Inspect the undersides of the leaves for spider mite damage (silvering to browning, with tiny red dots). Stop fertilizing by mid-November.
So in a nutshell, keep Hono Honos well watered, well fed, with warm temperatures and high humidity during their growing season. This will get their canes as long as possible. In their dormancy, lower the temperature and cut back on the watering and this will induce good flowering.
By following some of these basic rules of growing the Hono Hono, you too can be successful. By collecting the different types of Hono Hono, you may be able to stretch their blooming season from February to June. Just imagine having the beautiful flowers and wonderful fragrance for one third of the year! The best thing about growing Hono Hono orchids is that everyone is able to share their extra keikis with friends. This is truly what makes orchid growing fun in Hawai'i!
Reprinted with permission from Scot Mitamura, who is an Orchid Hortuculturalist for the Honolulu Botanical Gardens and has been growing and hybridizing orchids for over 38 years. He can be reached at firstname.lastname@example.org.
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