I just wanted to relate my experience of growing Vandas and their tolerances. I found that given the right conditions Vandas are easy to grow, but it took some trial and error to get there, but what’s new about growing orchids? It’s often all trial and error.

My first attempt was indoors using the vase technique; I found this had limited success for the following reasons. Firstly our homes are way too dry, vandas need high levels of humidity above 70% all the time. Secondly the roots need air movement and in the vase there wasn’t enough so the roots got infected with mould.

I was reluctant to move them to a greenhouse because of their perceived high temperature requirements. The literature says Vandas tolerate a night minimum no more that 12C and only for a short period of time. That ideally you would only allow nighttime temperatures to drop to 16C for the majority of the time and 12C only occasionally.

When I built my greenhouse and then converted it to an orchid house the priority was insulation. I was going to heat it with gas and then substitute the heating with battery powered electric. Neither was successful. On my allotment there is no access to mains electricity or ability to have an outside boiler with internal radiator system. That would push Dublin City Council over the edge!

The issue with gas heating was the ethylene that is a by product of burning; particularly in a low O2 conditions. Ethylene has a biological impact on plants and can affect a plant’s genetics.

To lower this risk I was forced to keep the gas heater down to just pilot light burning. That did deliver enough heat in the coldest winter months to keep night temperatures at 5-8C. Theoretically that was well below the tolerance for Vandas; however, although there is no doubt that the plants went into a static state, it didn’t harm them to the extent you would think. In fact I would propose that lack of winter light had more impact than lack of heat.

Of course these were shop-bought hybrid Vandas and hybrids are more tolerant of a wider range of conditions than a species.

I’ve spoken before about the issues of light; and it’s something that we don’t pay attention to. Even if I had a single glazed glasshouse that allowed maximum light; from October to February Ireland just doesn’t get enough sunlight for successful orchid cultivation. With Vandas, which like very high levels of light, this is an issue. Only the introduction of artificial lighting can help. Still I did get very good results from my greenhouse; but with the cost and impact of climate change I couldn’t justify growing orchids with a gas heater.