Dendrobium – Basics
Sunlight : 50 ~ 75% daily.
In orchid nurseries, nets are cast above the plants to create a semi-shaded environment (lath houses). This creates an environmental condition of 50 ~ 70% sunlight, which is conducive for growth and flowering and prevents leaves and flowers from sunburns. Unfortunately, such measures are not practical for most private collectors or home growers yet this does not mean that Dendrobiums can be deprived of sunlight. Sunlight is still the most important element, alongside water, to ensure a healthy plant and its flowering. For non-nursery environments, Dendrobiums should be exposed to at least 8 hours of sunlight a day. Look out for areas in your garden or home that are adequately exposed to the sun.
Watering is slightly trickier than sunlight, as it depends on environmental factors and pot medium. On a serious note, incorrect watering can induce plant death. Bear in mind that excessive watering induces root rot which promotes fungal growth, and other symptomatic issues (which is more detrimental than watering too little). That is why proper orchid pots are porous to allow excess water to sieve through. Moreover, Dendrobiums are typically grown in charcoal – just the right type of pot medium that does not retains excess water, and allows roots to “breathe”.
Optimally, Dendrobiums can be watered (mostly onto their roots) during times of the day when sunlight is mild (approx. 8 ~ 10 am ; 4 ~ 5 pm). These are times of the day whereby orchids can best absorb water for photosynthesizing (feeding); and there are several hours of daylight thereafter to help evaporate excess water. Watering during mid-day; or in the hot sun could “shock” the plants. Most of the principles behind orchid care lies in being gradual. Analogically speaking, it is very uncomfortable for the plants to be splashed with cool water when they are already heated up in the hot sun.
Dendrobium – Advanced
A simple technique is to tie the stems together – not too tightly, but just enough to keep them growing in a desired, compact manner. This is particularly effective when performed on younger Dendrobiums – as in building a good foundation.
Trimming & Pruning – Flowers
It has been said that cutting off Dendrobium flower stalks can spur production of more flowers. This is true with certain ambiguity in need of clarification. Technically, blossoming flowers are signs that conditions are right, and at the right conditions, the Dendrobium plant desires to propagate its genes – thus producing flower. In simple terms, cutting off the flower stalks will trigger Dendrobiums’ “survival instincts” – where its desire to flower is disrupted, thus encouraging it to produce even more flowers for compensation. However, the key is to cut the flower stalks before it fully blossoms. If one allows all flower buds to blossom and wither off, it is not going to make a big difference to cut it off or not. Harvesting the flowers prior to full bloom inclines flowering to a certain extent.
A common question posed is “why re-pot?”. Understandably, re-potting will subject the Dendrobium plant (in fact, all varieties of orchids) to certain degrees of stress. Moreover, root systems of Dendrobiums will take up to 3 ~ 5 months to re-established themselves in their new pots. And in unfortunate cases, re-potted Dendrobiums may stop thriving or end up dying. But this section hopes to alleviate some doubt, and also some fear with regards to altering the state of one’s plant rather drastically. To put things into perspective, the recovery time for re-potted Dendrobiums is relatively short, compared to other types of tropical orchids.
Re-potting is commonly done for 3 reasons:
1) Switching to a bigger-sized pots for more growing space
2) Propagating and growing of new pseudo-bulbs/keikis
3) The new pot is prettier
Larger pots provides adequate space for its roots and pseudo-bulbs to grow, which in turn, signals that the plant has adequate space to grow as a whole. In most orchid nurseries, pot sizes used for Dendrobiums are usually capped at around 25 ~ 30 centimeters (10 ~ 12 Inches) in diameter. Such sizes are trialed and tested for Dendrobiums to achieve their maximum height (varies between 1.3 ~ 2 meters amongst hybrids).
Care needs to be taken when one is cutting off unproductive old roots/stems, prior to re-potting – to avoid injuring the pseudo-bulbs. It is highly advisable to treat the plant/keikis with fungicide as cuts made are open wounds after all. Moreover, new charcoal can be used as they contain less pest/pathogens. Also, line the Dendrobium plant nearer the surface of the charcoal medium, rather than right at the bottom of the pot. This is because Dendrobium roots prefer to “breath”. Crucially, the re-potted Dendrobium should be secured in a stationary position for months to establish itself firmly.
In Toh Garden, Dendrobiums seedlings are grown in communal trays for several months, prior to growing in small pots. The small pots provides adequate space for a healthy root cluster to form; and limited peripheral space aids in upright growth of Dendrobium plantlets. Or rather, bigger pots have excessive peripheral space, allowing outward/side-way growth, instead of upright growth.