How To Water Your Orchids in a Greenhouse

I’m in the process of building an orchid greenhouse and I want to get it right the first time. It’s an expensive build and I don’t want to be redoing it in the future because I forgot something back in the initial phase.

Since watering orchids is one of the biggest source of orchid problems, I found myself thinking, “How do people water their orchids in a big greenhouse? Is it any different than on the tiny, metal bookshelf I have already set up? How does a bigger collection of orchids differ from a windowsill when it comes to watering? Surely they don’t take every single plant to the kitchen sink, or in this case, greenhouse sink!” So, in this article, I decided to set out and try to find out how orchid growers water their greenhouse orchid collection so that when my orchid greenhouse is finished, I’ll get it right (hopefully).

Water Concerns in General

Water issues are a growing concern worldwide, with population growth and urbanization putting increasing pressure on water supplies. Finding the right quantity and quality is the trick to successful orchid care. Excessive irrigation not only wastes water but also leads to the leaching of water and fertilizer into whatever you have below (or behind) your orchid greenhouse. This leaching results in runoff that can contaminate ground and surface water if not properly managed. Fertilizer runoff, particularly nitrogen and phosphorus, can contribute to the growth of algae in ponds and lakes, leading to water pollution and ecological imbalances.

When it comes to orchids, each genera has special growing conditions and the amount and pH of the water are just some of them. Most people say to let the potting media dry out completely before watering again, but they have forgotten that some orchids grow attached to the rock beside waterfalls. Those never dry out. Just because a Masdevallia likes to be soaked, a Cattleya may not. This is why I have to stress that it’s fundamental to know your specific orchid and how its natural habitat combines lighting, watering, humidity, and ventilation.

Without enough water, orchids can become dehydrated, leading to stunted growth, wilting, and even death. Too much water leads to the roots rotting, bacterial growth, and eventually, fungal growth.

Once you have researched your particular orchid to know it’s growing conditions, then tackle the water techniques. To use water more efficiently, you can implement proper irrigation techniques, such as drip irrigation or using moisture sensors, to deliver water directly to the plant’s roots and minimize water loss through evaporation. Additionally, capturing and reusing water runoff can help reduce water waste and prevent contamination of natural water sources.

Factors that Influence the Watering Schedule for Greenhouse Orchids

So… how much water do you use in a greenhouse? It depends (my least favorite answer). The amount of water required for orchids in a greenhouse can vary depending on several factors, including the potting media, size of the orchid, humidity levels, the weather outside (today and tomorrow), and the development of the root system. Once you have that information, then you need to ensure the proper growth and health of orchids in a greenhouse. To do this, it is crucial to establish a watering schedule that meets their specific needs. In this sense, the categories are the same for growing your orchids on the window sill, but the considerations for greenhouses on each topic are different.

Let’s look at those one by one.

1) POTTING MEDIA: When it comes to determining how much water to give greenhouse-grown orchids, it is important to consider the potting media. Orchids are typically grown in a well-draining medium, such as bark or sphagnum moss, not plant soil. But by now, you probably know that. Yet, I have to add that info here, just in case.

These potting materials (charcoal, bark, gravel, pea pebbles, Styrofoam, and coconut chips) allow excess water to drain away quickly, preventing waterlogged roots. As a general rule, orchids should be watered thoroughly, allowing the media to saturate fully and for the water to flow through the pot and drain out completely. This ensures that the roots receive adequate moisture without becoming waterlogged. My basic watering guide to orchids can be found here.

2) QUANTITY: The quantity of water may change slightly to a lesser amount when it comes to growing more orchids in a greenhouse than on your windowsill. They still will need the same amount of water as before, but a tad bit less. This is because of the high levels of humidity in the air. With such a high humidity, the water will evaporate inside their potting media at a slower rate than before.

You will find that you’ll also need less sphagnum moss in the greenhouse pot since the higher humidity range prevents the media to dry out completely. Bark will also break down quicker in the high humidity and high temperatures. (So, on this note, repotting will probably be necessary quicker than on your window sill.) It’s also a good idea to check the pH of the water exiting your media after you water the orchids to verify that the media is still good and fresh.

2) POT SIZE: The size of the orchid also plays a role in determining the watering needs. Larger and older orchids generally require more water than smaller ones, as they have a larger root system to support them. Not only the roots will need more water, but the water inside the pot will take longer to evaporate.

To add to this factor, the air inside the greenhouse will already be more saturated with water droplets, so water leaving the orchid through it’s leaves (due to evaporation) will take even longer. The longer water takes to evaporate, the longer the orchid roots will pause before taking in more water. This means that larger potted orchids will need more water initially but also longer intervals in between watering so that the media is completely dried out.

Make a mental note: larger pot —> more water —> more days for drying out.

The difference in pot size is also a factor if you are misting your orchids and the mister is aimed directly at the pot instead of in the air. A direct just of water means your orchids will be watered much more (if it’s on an automatic timer) than it would be if the mister is aimed for ambience humidity. Check to see where your mister is aimed.

A good rule of thumb is to group orchids together first by genera, then by pot size. That way you can water them quickly and uniformly since all the orchids in that particular side of the potting table are the same size and will require the same time of watering. I can also add specific fertilizers if my orchids need them (applying to the whole genera) while others can have different needs.

3) HUMIDITY: Humidity levels, as I mentioned before, in the greenhouse also affect the watering schedule for orchids. Greenhouses (that are totally enclosed during winter) have higher humidity levels, leveling at around 80%, which can reduce the frequency of watering. The increased humidity retains moisture in the potting media, allowing orchids to go longer between watering. The higher humidity level slows down the evaporation process, reducing the need for frequent watering. (Source)

On the downside, this also increases the bacteria and fungal build-up. You can add Physan 20 (or another bactericide) to your watering days as a preventive measure about once a month, just to be on the safe side.

One thing that stays the same in the greenhouse as on the window sill: it’s so important to monitor the moisture levels in the potting media and adjust the watering schedule as needed to prevent over or under-watering. Don’t just rely on the hygrometer on the wall, but check the media frequently with your finger.

One way to get around this excess humidity is to use terracotta pots, since they tend to dry out quicker. The quantity of water should remain the same in a terracotta pot, even if the frequency changes due to the humidity inside the greenhouse. This ensures that the orchids receive enough water to meet their needs.

How Greenhouse Temperature Affects Watering Schedules for Orchids

Temperature plays a crucial role in determining the watering schedule and quantity for orchids in a greenhouse since hot temperatures can cause the orchid to dry out faster due to increased evaporation. “The ideal summer temperature for a greenhouse is 75-85° F (24° – 30° C) during the day and 60-76° F (15° to 24° C) at night. In the winter, this changes to 65-70° F (18° to 21° C) in the day and 45° (7° C) at night.” (Source)

As a result of these elevated temperatures, it is important to water the orchids more frequently during hot weather to ensure they receive an adequate amount of moisture.

During the cool winter months, the watering schedule for orchids can be adjusted on the lower side, to account for the lower temperatures. However, even in a greenhouse, the reduction in watering should not be too significant, nor drastic. While the cooler temperatures and large humidifiers may slow down the evaporation process, it is still important to provide enough water to meet the orchid’s needs.

According to Nicole Fairs in EarthEasy, “Ventilate the greenhouse during the hotter part of the day so it does not have a temperature spike, and make sure cooling fans are turned off and ventilation windows are closed well before night or cloud cover to prevent excessive cooling.” Always monitor. It’s too easy to think that the greenhouse will be the solution to all my orchid’s problems, then not constantly monitor the conditions inside my greenhouse.

NOTE: Different orchid species may have varying temperature preferences and water requirements. Some drought-tolerant orchids may thrive in warmer temperatures and require more less frequent watering, (like Cattleyas) while others may prefer cooler temperatures and require less water. This can create a problem if you are using a central water system.

To get around this high level of variation and care preferences, I’ve seen people create physical barriers (like dividing your greenhouse into 2 or 3 sections) so it’s easier to control and maintain with uniform watering in that specific area. Also, some orchid sellers grow orchids in 3 or more specific greenhouses according to the temperature that they thrive during night:

Cool: 45°F to 55°F (7.2°C to 12.8°C)

Intermediate: 55°F to 60°F (12.8°C to 15.6°C)

Warm: 65°F (18.3°C) or higher

I can’t stress this enough: it is essential to research the specific needs of the orchid species being grown in the greenhouse to ensure optimal care. Don’t just think that now that you have a greenhouse you can relax on the proper care and orchid maintenance.

Can Orchids Go 3 Weeks Without Water?

I had to throw this question out there… What if I travel? Depending on the orchid species, it is possible for orchids to survive without water for up to three weeks in a greenhouse. Since the humidity is so high, my initial hypothesis was that yes, they can survive. However, it is important to note that this is not the ideal condition for orchids, and even though they are in a greenhouse, they generally should not go without water for such a long period of time.

Most orchids (not all) are native to tropical rain-forests where they receive regular rainfall. In their natural habitat, it rains almost every day, providing them with a constant supply of lukewarm water. Therefore, orchids have adapted to thrive in environments with high humidity and frequent watering. The big difference is that there is also constant air flow, which dries the orchid out quicker. Also, a potted orchid, even if it is in only charcoal or gravel, is not the same as a mounted orchid, and will need less watering.

In a greenhouse setting, where the conditions are controlled, it is crucial to replicate the natural environment as closely as possible, but 3 weeks is still a lot. Being locked up in a closed environment even if the watering system is hooked up and fans are automated, it’s not a good idea to leave them alone (and unsupervised) for that long. They are like kids in that aspect. This means providing orchids with regular watering to ensure they receive the moisture they need to stay healthy and vibrant.

If orchids are deprived of water for an extended period, they can suffer from dehydration, which can lead to wilting, yellowing leaves, and even death. I have several articles about those conditions, so if you think that your orchid is getting too dehydrated, you might want to look again at your watering schedule. It is essential to establish a consistent watering schedule for orchids in a greenhouse to prevent such issues.

How Do You Take Care of Orchids in a Greenhouse?

Besides watering, there are so many routines that I will need to take up once my greenhouse is built. I dream of this day so often. Lots of times, I imagine what my day will look like as I take care of a bigger collection than the one I grew back home in Kansas. What would that look like? From what I’ve seen, an orchid grower’s daily routine inside a greenhouse involves several important tasks to ensure the health and vitality of the plants. Potting, watering, fertilizing, trimming dead flower spikes, and checking for pests and diseases, potentially rotating plants, and isolating specific orchids are all essential aspects of caring for orchids in a greenhouse.

How to Water Orchids in a Greenhouse

Since your collection has grown, it’s probably enviable that you take each pot to the sink to water it. In a greenhouse, orchid growers have access to unique techniques for watering their plants that make our tasks easier. These watering techniques take advantage of the controlled environment and specialized equipment available in a greenhouse setting. Let’s look at each one individually.

1. Drip Irrigation: Drip irrigation is a popular technique that delivers water directly to the roots of the orchids (no leaves, crown, bulbs or stems) through the top of the potting media. This method involves a network of tubes or pipes with small emitters that release water slowly and evenly. Drip irrigation allows for precise control over the amount of water delivered to each plant, ensuring that the roots receive adequate moisture without the risk of over watering.

The water is released slowly and evenly, allowing it to be absorbed by the soil and reach the roots where it is needed most.

One of the main advantages of a drip irrigation system is that it minimizes excessive water loss due to evaporation or runoff. Unlike other watering methods, such as sprinklers, which can lead to water wastage, a drip system ensures that water is delivered precisely to the plants, reducing the risk of overwatering. This is particularly important for orchids, as they are sensitive to waterlogged conditions and can suffer from root and crown rot if they are consistently exposed to excessive moisture without ventilation. Additionally, a drip system can be easily automated and controlled, allowing for precise control over the amount and frequency of water delivered to the orchids.

What are the cons of a drip system? Price. It is important to be mindful of the cost associated with installing and maintaining a drip irrigation system. While the initial investment may be higher compared to other watering methods, the long-term benefits in terms of water savings and plant health make it a worthwhile investment for orchid care in a greenhouse.

2. Capillary Mats: Capillary mats are absorbent mats placed beneath the pots or trays of orchids. I debated about whether or not to include these since I didn’t find many people using them. These mats sit under the orchid pots and draw up water through capillary action, providing a constant supply of moisture to the potting media (you need lots of sphagnum moss for this). Capillary mats are particularly useful for orchids that prefer consistently moist conditions. They help maintain a stable moisture level in the growing medium, reducing the risk of under watering or over watering. More drought-loving orchids, like Cattleyas, won’t like a capillary mat.

One of the main advantages of using a capillary mat for orchids in a greenhouse is that it helps to maintain a stable moisture level in the growing medium. This is particularly beneficial for most orchids, as they prefer to be kept slightly moist, but not overly wet. The capillary mat allows the orchids to take up water as needed, preventing the roots from sitting in stagnant water and reducing the risk of root rot.

Another advantage of using a capillary mat is that it helps to reduce water waste. Unlike traditional watering methods, where excess water may run off or evaporate, the capillary mat ensures that water is efficiently absorbed by the plants. This can be especially important in a greenhouse setting, where water conservation is often a priority.

In terms of cost, a capillary mat is a relatively affordable option for watering orchids in a greenhouse. The price will depend on the size and quality of the mat, but overall, it is a cost-effective solution for maintaining proper hydration for your orchids. Check out this page on Amazon for a price range (affiliate link).

When using a capillary mat for orchid care, there are a few things to keep in mind. Firstly, it is important to choose a mat that is specifically designed for greenhouse use and is suitable for orchids. This will ensure that the mat is durable and can withstand the moisture-rich environment of a greenhouse.

3. Fogging Systems: Fogging systems create a fine mist of water droplets which get pushed around the greenhouse environment by large, oversized fans. Foggers are mainly used for cooling the greenhouses during excessively-high temperatures, and are not seen as much as watering systems in themselves, but I can’t rule them out.

When water droplets evaporate, they remove some heat in the air drying that process. (Source). Fogging is also meant to raise the humidity (smaller droplets like 5-20 microns) and to not be confused with misting (larger droplets, like 50 microns). Misting is a more commonly used watering system, better suited for smaller collections and done by hand with a spray bottle. Fogging, on the other hand, increases humidity levels and provides a gentle, indirect source of moisture for the orchids.

The mist settles on the roots, leaves, stems, and flower, hydrating the plants without saturating the growing medium.

The cons of a fogging system: water droplets are everywhere. Just be careful with the leaves. Fogging systems are especially beneficial for orchids that require high humidity levels. (Source)

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How Do You Take Care of Orchids in a Greenhouse?

Besides watering, there are so many routines that I will need to take up once my greenhouse is built. I dream of this day so often. Lots of times, I imagine what my day will look like as I take care of a bigger collection than the one I grew back home in Kansas. What would that look like? Form what I’ve seen, an orchid grower’s daily routine inside a greenhouse involves several important tasks to ensure the health and vitality of the plants. Potting, watering, fertilizing, trimming dead flower spikes, checking for pests and diseases, potentially rotating plants, and isolating specific orchids are all essential aspects of caring for orchids in a greenhouse.

I’m slowly adding these additional posts as time goes by, so please check up regularly. Thanks for reading and happy cultivating!