Orchids need strong light, high humidity, and airflow around the roots. Although these conditions seem simple enough to fulfill, orchids are quite fussy, and many people struggle to keep them healthy. Growing hydroponic orchids, also known as water culture, is easier because you will be providing the ideal environment for them to thrive.
Here’s how to grow hydroponics orchids:
- Choose the ideal orchid to grow hydroponically.
- Remove the orchids from the plastic pot.
- Wash all the debris from the roots and stem.
- Check the roots for signs of rot and discoloration.
- Choose an ideal bowl.
- Let the roots dry overnight.
- Add water for full or semi-water culture.
- Fertilize the orchids.
Growing orchids hydroponically mimics the natural environment in which orchids thrive. Some orchids, like Terrestrial orchids, do well under high humidity. This article will give a detailed step-by-step guide on how to grow orchids hydroponically.
1. Choose the Ideal Orchid to Grow Hydroponically
Orchids come in different shapes, sizes, colors, and fragrances. There are also varieties that you can grow hydroponically and those that you cannot. Terrestrial orchids, like the Cypripedium, Phalaenopsis, and Paphiopedilum varieties, are best suited for hydroponics because they thrive under high humidity.
Epiphyte orchids are not ideal for hydroponics because their roots absorb oxygen and nutrients in the air, and can go for a long time without water.
Besides the species, you also need to consider the age of the orchids. Newly acquired or young orchids are likely to adjust to water culture better than an orchid that grows in a different environment.
However, if you have older orchids and would still like to grow them hydroponically, you should transplant them after they fail to bloom or when the blooms have faded. Avoid changing the growing medium when the orchid is blooming.
2. Remove the Orchids From the Plastic Pot
If you are using store-bought orchids, remove them from the plastic pot and get rid of the sphagnum moss, pine bark, and all other debris. Orchids are sensitive to regular manipulation, so most stores do not change the medium even as the orchid grows.
You are likely to find heavily decomposed moss within the pot and around the roots. If you are changing the medium of your older orchid plants, you also need to remove them from the pot and remove all the debris from the roots.
3. Wash All the Debris From the Roots and Stem
If there is old debris stuck in the roots, soak the roots in water and wash them off. This is a critical step to growing hydroponic orchids because any leftover material will cause the roots to decompose when you transfer the orchid into the hydroponic system.
Besides causing root rot, the media may prevent new root growth.
If the potting medium proves difficult to remove, you should consider soaking the orchid in water for about 15 minutes multiple times a day. You can do this for two days if you need to, but you need to ensure no debris is left behind when you grow orchids hydroponically.
Some moss, bark, and other media stick on the stem, which is easy to miss, especially when your focus is on the roots. If you don’t remove the stuck media, mold will start forming around the stem, resulting in stunted growth.
This video is a great guide on how to prepare orchids for water culture:
4. Check Roots for Signs of Rot and Discoloration
Once the orchids are free of potting medium, you need to inspect the roots closely. Look for moldy, discolored, or squishy roots, as these roots will only worsen when they are left in water for extended periods.
Cut off the unhealthy roots with a sterilized pair of scissors. Soak cotton wool in alcohol and sterilize the scissors. Don’t worry if you end up with very few healthy roots because they are enough to sustain the orchid.
You’ll want to have a few healthy roots than keep roots that will compromise how well the orchids respond to water culture.
If the orchid is rootbound, gently detangle the roots while in water, which allows air to flow easily through the roots and improve nutrient absorption.
This video illustrates how to identify root rot in orchids and how to deal with it:
5. Choose an Ideal Bowl
When growing hydroponic orchids, the bowl you use should support the humidity needs of orchids. A circular bowl with a narrow mouth is ideal because it allows sufficient airflow and, at the same time, traps the humidity needed to keep the orchid healthy.
You should avoid short jars and those with a wide mouth because they encourage evaporation.
If you cut off many unhealthy roots, you may need a smaller bowl because the remaining roots should fit snugly.
Orchids growing underwater need to be checked regularly, which is why a clear glass or plastic bowl is critical. You need to observe the roots to determine if they are adjusting well. If they are not, you need to find out why.
Is the water too much or too little? Is the temperature okay? Most of the time, you may have to follow your intuition, especially if you’ve made changes that don’t seem to agree with the orchid.
6. Let the Roots Dry Overnight
Once you are sure that the roots and stem are free of debris, place the orchid on a paper towel and allow the roots to dry overnight.
Historically, dipping orchid roots in hydrogen peroxide was seen as a preventative measure against microorganisms responsible for root rot. However, while it is true that hydrogen peroxide prevents the growth of harmful microorganisms, it causes root decay and stunted growth.
Instead, you should leave the roots out to dry before placing the orchids in water.
7. Add Water for Full or Semi Water Culture
If you want a full water culture, you need to ensure ⅓ of the orchid roots are in water most of the time, so make sure you put enough water to cover the roots up to this point. For easier measurement, mark the water limit on the bowl so that you can observe how much water the orchids consume and how much to add.
For semi-water culture, you need to ensure ⅔ of the roots are covered in water. The difference between semi-water culture and full water culture is that orchids in semi-water culture sit in more water for two days and out of water for 4-5 days.
Orchids in full water culture sit in less water for four days and out of water for 2-3 days. You can drain the water from the bowl during dry days.
You may notice some dirt in the water the first few days, which is probably some of the debris left on the roots and stem. Pour this out after a day and add new water, while keeping the same level of water for full and semi hydroponics.
The water you choose to use is important. If possible, use distilled water because it does not contain chemicals present in tap water. You can also use rainwater, but whichever water you choose to use, always ensure the orchid leaves remain dry.
Full water and semi-water culture are discussed in detail in this video:
8. Fertilize the Orchids
Hydroponic orchids need to be fertilized because they have no alternative source of nutrients.
However, you need to be careful when fertilizing hydroponic orchids lest you overdo it. Fertilize the orchids sparingly after the first round of the dry cycle. When choosing the fertilizer to use, get one that’s suitable for orchids and ideal for the season.
For example, fertilizers can boost growth and bloom fertilizer when the orchid starts flowering.
Nitrogen is the primary nutrient in all fertilizers. However, you need to pay close attention when buying fertilizers for orchids, especially if you cannot find one specially made for orchids. Make sure the nitrogen source is not urea because orchids cannot break it down.
Instead, choose a fertilizer with nitrate-nitrogen or ammoniacal nitrogen.
When preparing the fertilizer mix, dilute the fertilizer and leave the orchids to complete the first wet and dry cycle before feeding them.
Make Sure the Orchid Roots Are the Correct Color
After the dry days, the roots of the orchids should be silvery or light gray. Prepare the fertilizer mix before the orchids are due for the wet cycle. Allow the fertilizer mix to sit for a few hours to allow the nutrients to dissolve. However, you shouldn’t let the fertilizer mix sit for more than a day.
Prepare the Roots for Absorption
Spray the orchid roots with water or dip them in water before putting the orchid in the fertilizer mix. This step is critical because you are preparing the orchid root for absorption. You don’t want to shock the orchid with fertilizer before it can absorb the nutrients.
After placing the orchids in plain water for a few minutes, transfer them into the nutrient mix and let them sit for a few hours. Ensure the water limit of the fertilizer mix is either ⅓ or ⅔ of the roots for full water culture and semi-water culture, respectively.
Do not leave the orchids in the fertilizer for the entire wet period because the orchids will absorb too much fertilizer. Remove the orchid from the fertilizer mix and continue the wet cycle in water free of fertilizer.
The orchid’s few hours in the fertilizer mix add up to the wet cycle. Finish the cycle, and proceed with the dry days.
If there are roots that do not directly contact the fertilizer, don’t worry about it. They will absorb the nutrients as the water evaporates.
How Often You Should Fertilize the Roots
You can fertilize the orchids once a week or once every other week. However, you should flush out the bowl once a week to wash off the salt build-up, especially if you use the same bowl for the wet cycles.
Observe the orchids closely. You have changed its growing environment, and the orchid is likely to show signs of rejection. However, a week or two is not enough to confirm how well the orchid is adjusting.
Keep observing it, but if it shows signs of overwatering or dehydration, you should consider changing the cycle from full water culture to semi-water culture and vice versa.
Semi-Hydroponics for Orchids
Besides the full and semi-water culture, the other method of growing orchids is using semi-hydroponics.
This method involves the use of growing media, such as LECA, perlite, rock wool, and gravel. Unlike the water culture method, semi-hydroponics involves using non-glass jars with drainage holes.
Place LECA in this well-drained pot and place the orchid. You then place this container in another container of water. The LECA will absorb the water and nutrients and then feed the orchids.
You’ll need to make sure that the orchid roots are embedded in the LECA. However, the aerial roots should remain uncovered to absorb oxygen.
This method is easier if you are not around to follow the dry and wet cycle. It takes away the guesswork of determining how much water to use and how often to water the orchids.
The LECA is not compact, so the orchid roots are exposed to plenty of air circulation. The LECA also holds water for weeks, so you need not worry about watering the orchids often.
You may need to top up water in the reservoir after two to three weeks.
Run a wick through the drainage holes in the pot, with one end in the water reservoir and the other end embedded within the LECA. The wick will feed the orchids without running the risk of overwatering.
Before placing the orchids in the container containing the LECA, you should wash off all the media, as most stores use moss or bark, which tends to stick to the roots. Follow the same cleaning procedure as semi and full-water culture.
Once the roots are clean, leave them to dry out overnight. Flush them with water the next day and place them in the container with LECA.
How to Fertilize Orchids Grown Semi-Hydroponically
As LECA absorbs water, it usually retains some salts. Before using fertilizer, flush out the LECA with plain water, and add a little fertilizer to the water reservoir. Orchids do not need a lot of nutrients, so you should feed them sparingly.
Since the LECA retains the nutrients and feeds the orchid over a long period, only add fertilizer to the water once a month.
As the orchid grows, the roots will get long enough to get into the pot containing the water. You need to check the root system regularly because you don’t want your orchid’s roots to sit in water. When the roots grow too long, you should change the container to a larger, deeper one.
Ideal Conditions for Water-Based Cultivation
Growing orchids hydroponically is fairly foolproof if the orchid species is suitable. Hydroponic orchids often adapt to growing in water if the conditions are ideal.
Here are the ideal conditions for hydroponic orchids:
Temperature & Humidity
Most orchids thrive in temperatures of 66-79 °F (19-26 °C). Some orchids, like Cymbidium, Miltonia, Dendrobium, and Paphiopedilum, prefer lower temperatures of 54-70 °F (12-21 °C).
Humidity levels of 40-80% are suitable. This is one of the reasons the mouth of the bowl should be narrow to contain humidity within acceptable levels.
Water pH & Changes
The water pH should be 5.5 to 6.5 when growing hydroponic orchids. You should also change the water once a week when growing semi-hydroponics.
400 watts of lighting is sufficient for hydroponic orchids. If the lighting is too strong for the orchids, you can move them further from the lighting.
When the orchids are in a vegetative phase, you’ll want to choose to grow lights with a lot of blue light. However, you will need to switch to warmer light bulbs when the orchid starts flowering. Once they are in full bloom, hydroponic orchids no longer need to grow lights.
Having good ventilation will keep fungus and viruses circulating in the room from affecting the hydroponic orchids.
Telltale Signs Your Orchids Are Not Adjusting
Now that you are growing your orchids hydroponically, you need to watch the roots regularly to make sure they are adjusting to the new environment.
You also must follow the dry and wet orchid cycle for full and semi-water culture without alterations. Leaving the orchids in water for too long will cause root rot, but if they stay out of water for longer than they should, they will be dehydrated.
These are the signs that show hydroponic orchids are not adjusting to the change in environment:
Dark and Mushy Roots
Dark and mushy roots are usually a sign that your orchid is overwatered and not responding well to hydroponics. Sometimes the roots may be thin, shriveled, and dry, which shows they are not receiving enough water. The cause may be too little water, so the roots are not absorbing enough water, or the dry cycle is too long.
Shriveled & Yellowing Leaves
In addition to shriveled and yellowing leaves, sometimes, dark spots may appear on the leaves if the orchid isn’t adjusting well.
Growth Underneath the Leaves
Growth underneath the leaves is usually a sign of overwatering and as the leaves rot, mold starts forming on the leaves. You may miss this sign if you don’t check the leaves. Should this happen, you should consider full water culture since the orchid has more dry days.
The Plant Appears Weak or Isn’t Growing
If the orchid appears to show signs of weakness after several wet and dry cycles, it is not adjusting.
You might also notice that instead of growing bigger, the orchids are becoming smaller. Over time, the orchids are supposed to outgrow the pots. However, if the orchids maintain the same size or become smaller, it is a sign that something is wrong.
Issues With Flowering
You may notice damaged flowers, or the orchid might flower before it matures. The latter is usually a distress call when the plant reproduces as a defense mechanism when it feels like its life is threatened.
Indicators of Thriving Orchids
Orchids usually take a little time to adjust to a change of environment. However, they usually pick up quickly, especially if the hydroponic conditions are ideal. You can tell when an orchid is struggling to survive and when it is thriving.
These are some signs of a healthy hydroponic orchid:
- Thick, rubbery, and uniformly green leaves
- Vibrant and colorful blooms
- White aerial roots with green, shiny tips. If the orchid has longer green tips, it is doing well.
- If you use LECA for semi-hydroponics, it shouldn’t be bone dry or too wet. If it is barely moist, then you are watering the orchid well.
- Thick white or gray roots
Advantages of Growing Orchids Hydroponically
Many people struggle to grow orchids because it is one of the plants that require specific care. Guessing whether you are watering enough, feeding the orchids as you should, or exposing the roots to enough dry days can be overwhelming.
Growing hydroponic orchids has several advantages:
- You have greater control over the growing environment, such as lighting, watering, and feeding.
- The growth and care patterns are predictable. For example, you know for full water culture, the orchids sit in water for 4 days and 2-3 dry days.
- Since the roots are visible, you can easily tell when something is wrong based on their appearance.
- The LECA used in semi-hydroponics is cleaner and easier to use than traditional grow media, like moss and bark. You don’t need to worry about the material sticking to the roots and causing them to decompose.
- You can use semi-hydroponics with LECA as the growing media if you travel a lot. This way, you’ll know your orchids will not need watering for the next 2-3 weeks.
- Orchids do not like to be handled all the time, which is sometimes unavoidable if the media breaks down. Hydroponic orchids do not need to be repotted as frequently as those grown in other media.
Challenges: Knowledge Requirements and Tailored Water Culture
Although hydroponic orchids have several advantages over conventional growing methods, it is not without their challenges. Before choosing to grow your orchids hydroponically, you need to consider the challenges so that you can find ways to overcome them.
These are the challenges of growing hydroponic orchids:
- You need to have some knowledge about orchids. For example, you should look at the roots and tell if they are overwatered or dehydrated. You also need to identify any issues early so that you can save the orchid.
- Some orchids respond to semi-water culture, while others need to have their roots fully submerged in water.
Once you decide to grow hydroponic orchids, you need to ensure you get everything right. The choice of orchids, the steps to follow, and the conditions suitable for hydroponic orchids are all critical in orchid hydroponics. When you follow all the dos and don’ts, the chances of your orchids adapting to the change of environment are high.