Root Advice

Having trouble getting roots to grow on your orchids?

A little joke here: Someone said that he will sell you a Paphiopedilum with one growth for $10.00; two growths plants will cost $20.00 and so forth. If you do want a Paphiopedilum with roots, you have to triple the initial price.

The basic fact to remember is that roots are necessary to supply the plants with food, drink and air on a steady basis. Without roots, few plants will manage to stay alive very long. In the wild, the roots also hold the plants in place, whether it is in trees for epiphytic plants, in soil or on rocks for others. Rain, dew and fog will of course be involved, as is watering, fertilizer and an appropriate potting method in captivity. Some leafless orchids utilize their roots to achieve photosynthesis.

When you need to encourage (particularly epiphytic) plants to make roots, you must let the medium go quite dry, so the poor dears will have to send out roots to find water. You don’t want your plants to shrivel and die, but you don’t want the bases waterlogged and allow rot to settle in. Epiphytic roots need much fresh air, which will be available in a dryer mix – see below for some suggestions. You know how “damp” you need to have your clothes for ironing? Well, that is about how “damp” the mix may be – not moist, not wet – just barely damp. Some people also apply rooting hormones, vitamin B solutions and even high phosphorus fertilizers (10-52-10) that are said to stimulate root growth, as does bottom heat (put the plant over a heating pad). Our tropical orchids will not send out fresh roots when it is too cold for them – they will go dormant or just give up and die. They can also die off easily in old, broken-down potting mix which will hold a lot of moisture but no air – this can even contain pathogens like fungi and bad bacteria which cause rotting of the roots and eventually kill the plants. Even though orchids and their roots thrive in a humid atmosphere, a constantly wet environment is only nice for water lilies and similar plants – it is death for orchids.

Also worth remembering is that plants on slabs etc. dry out faster, as do bare-rooted items, which may need daily misting. Small clay pots dry out very fast; small plastic pots hold a little more water; large clay pots can have wet centres; large plastic pots can hold a lot of water. This rule can be adapted by drilling many holes in the pots. Large grade mixes dry out faster than fine grade; moss can stay moist for weeks. Before you water plants in moss, you have to find out what the middle of the pot feels like – is it still damp? Then wait a few more days. That is why I don’t particularly like moss (only) as potting medium – I enjoy watering my orchids.

To avoid the wet centres in large pots, some people put a small clay pot into the pot first, then place the plant on top of that and surround the whole thing with potting mix. After observing how several of my orchids dislike having their roots touch those Styrofoam nuggets (they turn back from the plastic and try to grow the other way), I am not using these anymore. For some orchids, they work just fine by providing more (non-rotting) drainage. In both methods (inserting a small pot in the middle of a large pot and/or large drainage pieces in the bottom of any pot), the roots will have access to fresh air. There are the “Rand’s Air cone” pots which allow good airflow through the potting mix. These pots are made of opaque plastic and even allow roots to photosynthesize. In clay or mesh pots, air will also come from the sides, and mounted plants grow like nature intended epiphytes to grow. It also helps to provide bottom heat to your plants – they do much better when the pots are supplied with gentle, steady heat from below; this is especially important during our cold months.

So, with all this “Root Advice”, all our orchids will grow roots like mad this summer, right? I sure hope so!

Ingrid Schmidt-Ostrander - Canadian Orchid Congress