Growing in Your Greenhouse: Orchids

Brian Bill

Brian Bill | February 23, 2022

Growing in Your Greenhouse: Orchids

February is on its way out and while the temperature might not reflect this fact, the extended sunlight is a pretty good indicator. I know there’s been freezing temperatures of late, blame the groundhog, but it’s nearly March! Generally speaking, March brings with it warm weather, at least towards the end of the month, so just hold out a bit longer and maybe this wind will go away. As we encroach upon spring, there’s one thing on everyone’s minds. Well, maybe there’s a few things. But common among them is the beautiful explosion of color and fragrance that comes with spring blooms. That’s right, I’m talking about flowers! Flowers are at the top of most people’s lists when the sun starts to shine. Some people wear them in their hair, some wear them as designs on their clothing, others grow them and almost everyone appreciates getting them from loved ones. Yes, flowers are a uniquely beautiful aspect of nature that inspire many. Roughly $26 billion is spent each year in the United States on floral products. Over 23,000 different firms operate in the flower market ranging from wholesalers like 1-800-Flowers to the individual stall vendors you find at nearly any farmers market and that’s just domestically. Flowers are a global phenomenon, sparking the migration and subsequent growth in popularity in rare flowers across the world. This increase in demand for rare flowers, in part, sparked the rise of greenhouses. Greenhouses, as I’m sure you’re aware, allow one to control the indoor environment and alter it to cater to the plants to be grown inside. Once floral greenhouses began to spread, one family of flower in particular was a common staple being grown. In Latin, Orchidaceae, or to the layman the Orchid. Consisting of around 28,000 currently accepted species, Orchids are one of the most prolific and varied flower families. Generally speaking, orchids are recognizable by their unique bilateral symmetry of the flower. Do not, however, confuse this to mean that all orchids look alike. They very much do not. Now, it would take near a lifetime of research and experience to tell you all there is to know about growing orchids in your greenhouse. While I cannot provide that, I can offer some basic research and discussion on a few different orchid families and how to grow them successfully in your greenhouse.

As with any other plant, the environment you create in your greenhouse should be catered to the plant you are growing. The basic idea is to mimic the plants native climate as best as possible, this ensures the plant has its best chance to thrive. Do your research and know what plant you want to grow before you start. Orchids, being the wide ranging family they are, have different species that require different microclimates within their greenhouses. There are essentially three different types of orchid varieties; cool, intermediate and warm growing. As you can likely derive by the category titles, these orchids mainly differ in the temperatures they need to be successful. Generally speaking, all orchids need a 10-15°F night time temperature drop in order to bloom. Meaning, if your day temperature is 75°F, your night time temperature needs to be in the range of 60-65°F. The drop in temperature cools down the plant and allows for adequate gas exchange, or breathing. A lack of cool temperatures at night will likely result in heat stress in your orchid, which is less than ideal. However, if it gets too cold at night you may observe blackened tips on the leaves as well as flowers wilting.

Cool temperature orchids tolerate low temperatures of 50°F during the winter. During the summer, the maximum temperature they will tolerate is 75°F.

Intermediate temperature orchids greatly prefer a range of 55-85°F.

Warm temperature orchids grow best in a range of 64-90°F.

Again, make sure that you are dropping the night time temperature accordingly. Research which orchid type you are planning to grow and make sure you adjust your greenhouse. The main difference between the growing varieties is the elevation in which they grow naturally. Generally speaking, the cooler temperature orchids grow higher up, sometimes even just the higher limbs of a tree. The warm temperature orchids can normally be found in tropical areas close to the equator. While the intermediate temperature orchids grow in elevations ranging from 1,000-3,000 feet, depending on how far away from the equator you are. Intermediate varieties make up the majority of orchids you will find available for purchase to be kept indoors. Generally speaking, you won’t find warm temperature orchids inside of anyone’s home as their high temperature and humidity requirements would result in moldy walls. However, in your greenhouse you should be fine. So long as you keep the air circulating properly and vent out unnecessary humidity.

Speaking of ventilation. Orchids require moisture essentially at all times. Moist air is best and can be achieved by potting on top of moist gravel. In addition to constant moisture, orchids need a lot of air circulation. In nature, orchids are generally found in tropical areas. The tropics, more often than not, are places that are warm and near water which generally coincides with wind. Warm, moist winds penetrate every aspect of these plants in the wild, so your greenhouse will have to mimic this. The roots and eventually the whole plant will die if there isn’t sufficient air. The soil of your orchids should remain moist, but not water logged. Having moist, humid air circulating through your greenhouse will ensure that your orchids will remain nice and happy. Venting is likely to not be enough to create the artificial wind you require so invest in some fans and place them strategically throughout your greenhouse. A stagnant environment can kill orchids just as quick as not giving them adequate water.

On the subject of water, don’t over-do it. Orchids don’t possess the same water storage capabilities that other plants enjoy. When you look at orchid’s structure, they generally use other, larger plants to support their vertical growth. Hence why you need to use supports when growing them yourself. Because of this, the root system is not like most plants that can support themselves. Orchid roots can easily rot when exposed to too much water. Water from above once a week, allowing the excess water to drain off and be removed from under the pot. Misting foliage and exposed roots can be beneficial, however be sure to reduce the humidity exposure during the winter. Water requirements in general decrease during the winter, but be sure to keep the compost moist.

Feeding your orchids is also something you should keep in mind. Generally speaking, orchids don’t have huge appetites. Many orchids will grow and flower just fine for years on end without ever being given fertilizer. However, if you want to help your plants get some size, a 20-20-20 fertilizer is recommended (any of these should do). As a rule of thumb, you can try feeding your orchid once every three weeks, or every third watering. Make sure the soil is moist before adding fertilizer to the potting medium. During the summer and fall you can increase feedings to almost weekly if not bi-weekly, just be careful not to overwater. It is also a good idea to give your orchid a rest period during the winter to eliminate stress of your plants.

Now that you’ve gotten all of that taken care of, it’s time to talk about lighting. Aside from temperature, lighting is probably the most important thing to pay attention to when growing orchids. Beware, your orchids might be a little picky when it comes to light. They require bright but filtered light, but you don’t want to leave them in direct sunlight. Too much direct light and heat can burn the foliage. Blinders and Knitted Shade Panels are a great way to keep your plants from getting too hot. Artificial lighting can work if your greenhouse has been shaded by forces outside of your control, but it is always best to expose your orchids to as much natural light as possible. Natural sunlight hours generally range from 8-10 hours so if you are using artificial light make sure to mimic natural settings. It’s very easy to shade sunlight that is too intense, it’s much harder and energy intensive to try and replicate the light. Lighting, like heating can get rather expensive if growing during the winter months. However, these are the two most important things to keep track of if you want your orchids to flower.

Beyond all that, orchids should be dealt with much like any other plants! Make sure to give each plant the necessary space it needs to be happy and healthy. Especially in the humid environment required for growing orchids it is essential to keep plants spaced out to prevent the buildup of unnecessary moisture which could lead to molds and fungus. Proper ventilation can help keep down excess moisture but fans are very important to keep the air in your greenhouse moving about preventing the place getting stale. If you’re new to orchids and one takes a starts to lose its flowers, you can bring it back to bloom. With proper care you can have your orchid blooming again relatively soon and keep the flowers for up to months depending on the variety. Many of the tips for getting orchids to re-bloom are similar to the tips to ensure they grow correctly (go figure) so if you’ve read up until now you should be alright! Make sure you keep up with sunlight and watering while making sure the roots have enough oxygen. Sounds simple enough, but be warned that orchids are not for those who don’t like to care for their plants. These beauties can grow big and strong but they need your attention. One thing to remember above all, with orchids it’s not about getting the most expensive things to care for them but rather to make sure you are spending the necessary time on them.

I wish you luck! Orchids can be tricky, but boy are they worth it when they bloom. Each so intricate and beautiful all the while so elegantly fragrant, just a wonder of a plant. Thanks again for reading, until next time!

-Brian Bill