Moving Orchids Outside for the Summer: Foresight and Monitoring

Many authors recommend moving orchids outdoors for the summer to give them a little boost of energy. This practice is indeed very beneficial for many orchids, especially if you live in a temperate region. Unfortunately, for orchid lovers living in northern regions, a stay in the garden can be riskier and more problematic. Let’s examine the benefits and the risks associated with this transition to the outdoors, which is much more radical than it seems.

A Stay In the Garden Can Have Several Advantages.

Outdoors, the light is more natural and, above all, more complete, with a wider spectrum including « antiseptic » ultraviolet rays and deep reds that stimulate growth and phototropism. The glass in our homes lets in very little of these light components, which are so useful for the hygiene of indoor growing rooms. Despite our best efforts, it is very difficult to reproduce such a complete light spectrum with artificial lighting. In short, the change in brightness is radical when we take our orchids outside to let them enjoy the great outdoors.

In addition, the temperature cycles are more stimulating than indoors and the aeration of the plants is also more natural and more effective in the garden.

With proper watering discipline, we can ensure optimal growth for our orchids in the summer. All the elements necessary for photosynthesis (light, moisture, natural temperature cycle, and adequate ventilation) are then reinforced. All of this should result in healthier orchids and more abundant flowering. As a reminder, the column on photosynthesis is available here.

On a more practical level, some collectors will also appreciate the energy savings that gardening offers, by reducing the need for artificial lighting for a few months. It will also help to avoid some of the problems of overheated indoors caused by the heat of the summer sun, especially in rooms that include large windows.

The Associated Risks Need To Be Carefully Managed.

More stimulating growing environments are obviously riskier, especially after a sudden transition from indoors to outdoors. In fact, your orchids may not be able to withstand the much more intense outdoor conditions. To prevent sunburn, place your plants under trees or shade structures such as a lath house or semitransparent canvas, so that they are never exposed to more than 50% of the sun’s rays. Direct sunlight should be avoided during midday period, for example between 10 am and 4 pm, as the risk of leaf burn is too high.

Too much and/or too-frequent rain is also a significant risk. We should therefore place our orchids in a location that is sheltered from rain and strong winds, while maintaining as regular and constant air circulation.

Night temperature tolerance will be the main factor in deciding when to move orchids outdoors. Most of our orchids come from tropical regions and tolerate the heat of our summers very well, but the cool nights can be very stressful for them. Warm tropical (e.g., Phalaenopsis and Vandas) will prefer nights above 15°C, although they can tolerate occasional drops to 10°C. Cattleyas and Oncidiums can be moved outdoors if night temperatures remain above 12°C. A few rare orchids, such as Cymbidiums and some Dendrobiums, can tolerate temperatures as low as 5°C, but these are considered exceptions. If in doubt, do not move your orchids outside until night-time temperatures regularly exceed 14-16°C. Conversely, at the end of the summer, we will bring in warm tropical plants first to prevent them from getting too cold.

For Some Orchids, the Outdoors Is Too Risky and Should Be Very Limited or Avoided Altogether.

Canada”s climate is far from tropical conditions—that’s for sure. Not only are the minimum and maximum temperatures different, but the seasonal variations are much more pronounced. This is why great care must be taken with the more sensitive orchids. For example, Aeranthes, deciduous Calantes, Cynoches, Miltoniopsis, some Paphiopedilums, and Psycopsis are rarely taken outdoors. Some more dedicated collectors will take these plants out during the day just to give them a little extra vitality, but bring them back inside in the early evening to avoid cold damage.

It Is Wise To Have a Strategy for Repelling Insects.

Insect infestations are rather rare in orchid collections kept in the garden. However, slugs and snails can be encountered and can be easily controlled with slug pellets. Diatomaceous earth can also be spread around our plants to restrict the movement of crawling insects. Finally, applying an insect and spider repellent such as insecticidal soap and neem oil can be very useful. The solution should be applied directly to the foliage every 3 to 4 weeks to ensure continued effectiveness.

Some Practical Tips to Enhance Your Summer Experience.

If you decide to move some orchids outside, it may be wise to plan carefully.

About Your Outdoor Installations:

Orchid pots should never be placed directly on the ground. The risk of insect infestation (especially ants) is far too high. It is therefore preferable to use tables with a metal (or glass) surface, which are more hygienic and much easier to keep clean. If you choose to use a wooden table, it is advisable to cover it with aluminum foil to prevent the wooden surface from contaminating your growing pots (and vice versa). Wooden surfaces are often rich in unwanted fungi and bacteria. Aluminum is also said to have certain insect and pest repellent properties, although copper is clearly better in this respect. Finally, in some cases, you can hang your plants using a metal wire wrapped securely around a tree branch or a fence protected from strong winds and direct sunlight.

Regular Maintenance

You’ll need to inspect your outdoor plants regularly. I recommend a weekly inspection to quickly detect any problems with sunburn, stagnant water, or insect infestation.

It’s normal to water outdoor plants a little more often. As suggested in a previous column, using bamboo sticks inserted into the substrate will give you a clear indication of the moisture level in the center of the pot. You’ll just have to check it a little more often.

It’s also a good idea to space your plants to allow for the air circulation. That is so essential for healthy orchid growth. A preventative treatment with insecticidal soap is also recommended monthly. A more thorough cleaning procedure will be described in the August column, just in time for the return to the house.

If you notice that one of your plants is beginning to flower, it’s best to bring it indoors so that it can complete its delicate flowering process away from the elements.

Thanks

The author would like to thank Marc Better for allowing the use of photographs of his outdoor installation – so well designed and executed. Marc is a highly experienced American orchid grower.

Editor’s Note

Mr. Charpentier’s columns on orchids are published on the Laidback Gardener website under a legal “Copyleft” model. Horticultural societies that wish to do so may include his columns in their technical journal or simply distribute the internet link to their members. However, please include the following statement:

This article was originally published in French on the JardinierParesseux.com website and in English on the LaidBackGardener blog.