Orchid Repotting Notes, Part 9: Exploring the Mysteries of Orchid Roots
■ Repotting Notes [9. Exploring Orchid Roots]
It had been two years without repotting. Usually I still selectively repot to observe, sometimes not even sparing the hot summer. However, most of the pots I repot in summer are sickly or ordinary plants, so that for theorchidsI keep the condition of the roots under constant observation. Judging from the orchid roots turned out in this large-scale repotting, there were quite a lot of roots, and they were not short either, yet they were still not ideal. The main problem was that the root tips had not grown well: first, the roots became rather thin toward the root tips; second, there were very few crystal heads on the roots, with the tips forming only slightly, showing signs of stunted growth. On analysis, the main cause was that the potting mix was coarser in the lower part during preparation, making it hard for the lower roots to spread, and the fertilizer content was the same as in the upper part, appearing slightly too strong, which was unfavorable for lean cultivation of the lower roots. Perhaps the repotting was too early and secondary root growth had not yet begun, or perhaps some step went wrong and secondary roots could not form. In short, the quality of orchid roots cannot be judged by seeing many roots alone; the quality of the roots must also be considered.
What kind of orchid roots are ideal roots? Yaoyuan believes: first, the root system is normal in number and grows relatively vertically downward; second, great-grandparent-generation plants shed few roots; third, the whole root is basically uniform in thickness; fourth, there are many crystal heads on the roots; fifth, old roots are pale yellow and new roots are tender white; sixth, the number of new roots can exceed the roots of old plants; seventh, secondary roots develop normally; eighth, the roots are long and not short; ninth, although the roots rub against the potting mix, the surface is not broken or injured; tenth, there are many regenerated roots from broken roots.
To achieve the above ten points, the orchid can be considered to have been cultivated properly. But in practice, unexpected things often happen that cause poor root development or even root failure. Now, regarding the reasons why orchid roots do not grow well, I will talk about some of Yaoyuan's own experiences.
Orchids with few roots mostly fail to produce roots because the potting mix is too rich or too wet; early root shedding of old plants is often a sign of poor growth in new plants; orchid roots that are thick on top and thin below are related to insufficient fertilizer and water; few crystal heads on the roots indicate stunted growth of the orchid, caused by aged potting mix, blocked aeration, or slightly insufficient water; local blackening or most of the root changing color is caused by too much fertilizer and water or by fungal infection; failure to produce new roots is related to improper control of fertilizer and water or to the surface being too dry; the period of secondary root development is mostly in autumn, so attention must be paid to not letting things dry out in autumn; thick and short roots are basically caused by excessive fertilizer; damage to root tips is related to coarse potting mix; failure to produce roots from broken roots is caused by improper cleaning during repotting or by excessive water and fertilizer.
Ancient orchid books discuss cutting away or shortening excessive and overly long orchid roots during repotting. Cutting away excess old roots to free up space is beneficial for new root development, which is relatively easy to understand; but the practice of shortening most overly long orchid roots is somewhat hard to understand. In practice, Yaoyuan has never dared to cut away overly long orchid roots, and only when the roots are truly too long does he steel himself to make a cut…… (2006-09-28)