Orchid Seedling Care: Deflasking, Potting, & Watering

In Breeding, Flasking & Invitro Propagation
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After deflasking my first orchid seedlings 2.5 years ago, and subsequently breeding and growing my own orchids from seed, I’ve had a lot of time to test and observe different methods of care for exceptionally tiny orchids. When I first started sowing orchid seeds in flask, I often had issues with contamination and had to deflask seedlings early. Sometimes the plants I was deflasking only had one leaf and barely a root nub (and while they didn’t all survive, a good chunk did considering how small they were). A lot of people told me those plants would die but with the methods outlined in this post, I’m going to share with you how I manage to grow even the tiniest seedlings in my dry home without using seedling domes or humidifiers to increase humidity. In fact, for most orchids I specifically recommend you DON’T use humidity domes because they frequently lead to rot or fungal issues that quickly kill small seedlings.

Like my recommendations for standard orchid care, there are 4 main components to seedling care: root health (which we solve with a water retentive potting media and tight cycles of wet and dryness), overall hydration (which we solve with active irrigation on a regular cycle), leaf health (which we solve with good light and localized humidity), and finally the building blocks for good growth (which we solve by providing good fertilizer at a weak concentration, every time we water). I’m going to break each one of these components down in detail and show photos of the process so that you’re able to understand and extract that information. Then you too can grow seedling orchids and have success like I have.

Photo of Orchid Seedling Progress

One important note about growing orchid seedlings: they’re are TINY, right? Their small physical size means they are not as forgiving of dehydration, bad (too wet for too long) root conditions or low light; large plants are much more forgiving because they have more biomass to distribute the deficiency (if a big plant is dry for 12h it overall has more water it can stand to lose—a tiny plant can easily collapse if it goes too dry for too long). Your ability to successfully care for seedling orchids will depend on your ability to adhere to routine, provide consistent cycles of conditions, and to observe oddities in your plants so that you can correct for problems quickly. I don’t personally feel that it’s difficult, but understand it’s a commitment and seedling orchids take about 1-2 years at a minimum to get to “regular sized flowering plants.”

4 Points of Orchid Seedling Care

1. Orchid Seedling Root Health

Potting Media for Seedling Orchids

When potting orchid seedlings I use a layered approach. Bark and perlite (50/50) on the lower half, with a thin layer of sphagnum moss around the roots and under the leaves. If your climate is naturally humid, you could probably use LECA instead of bark; however I use bark because it holds 2x the amount of water that LECA holds. This buys me a bit more time between watering because the bark release more water a little bit longer, ensuring that the potting mix doesn’t dry out too quickly. And I know this…I’ve tried using LECA alone; it just dries out too fast, even with sphagnum moss on top.

Deflasking & Potting Orchid Seedlings

Here are some photos of the process so you can see exactly how I pot my seedlings up.

Potting Orchid Seedlings Image Sequence

Potting Tip for Increasing Humidity

You might notice in some of my photos that I leave a high lip on the pots above the seedlings—that helps hold humidity near the plants as the water evaporates from the moss. If I don’t deep-pot them like this, I’ll often use a plastic soup container as a cache pot to provide that tall lip. You don’t want to put a lid on it though… you are relying on evaporation in the potting media to provide localized humidity and transpiration from the plant to move nutrients through your plant. If you make the conditions too humid, the need to actively water stops and it limits your ability to push nutrients through the plant on a regular basis. This is why I don’t use humidity domes—I’ve killed too many seedlings in those damn things.

Watering Seedlings for Root Health

The biggest thing is to understand is hydration cycles. Follow wet/dry cycles, targeting a 3-5 day dry out period. If they’re drying too fast or too slow, adjust the ratios of sphagnum moss in your potting mix; you can blend some sphagnum into the bark starting at about 10-15% to hold more water and slow the dry-out period OR you can add more perlite to increase airflow and shorten the dry-out period. You can also change the size of the bark chunks (larger for faster drying, smaller for slower), or adjust the pot size (smaller pots dry faster, larger pots dry slower) to modify the dry-out period. Try to target that 3-5 day dry out period though.

If moss is wet for too long, then bacteria and pathogens thrive or the plants just flip out b/c they can’t grow well in wetness and the roots don’t thrive. It will depend on the type of orchid you’re growing; however, especially for phals, vandas and cattleyas (which specifically need distinct wet/dry cycles) don’t let them stay continuously moist or you might risk rotting the few roots they have.

One exception to wet/dry cycles: phragmipediums. Like adult phrags, I let the pot of seedlings sit in a shallow tray of water between waterings. You’ll still need to actively irrigate the plants and water the pots every week…but specifically make sure that the top layer of moss doesn’t go crunchy dry between waterings.

Phragmipdium Seedlings in Cache Pot (with 1/4 inch of water)

2. Watering Orchid Seedlings

Top Watering (foliar feeding, full drench, dry out)

I water my seedling orchids like I do all of my other plants – from the top like it’s raining. Why? Because orchids are foliar feeders and they take in nutrients both through their leaves and through their roots. This is why YOU CAN’T use a humidity dome. You WANT your plant’s leaves and roots to dry out between waterings…otherwise you’ll risk getting leaf and/or root rot. To help small seedling survive, you need to actively irrigate and drench the leaves and roots on watering day so that there is an ebb and flow of both water and nutrients on regular cycles.

Here’s a video of how I water:

 

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Wet/Dry Cycles

Knowing when to water such tiny plants can feel like a bit of a guessing game. However, I have found that I can judge watering times based on the moss. When the moss feels fluffy and warm to touch, it’s time to water. You ideally want to water just before the moss gets crunchy—but if you’re checking your seedlings and the moss is crunch, water ASAP. If the moss looks dark and feels cool/damp when you touch it, then it’s still too moist and should not be watered yet.

Examples of when to water: Here are photos of phalaenopsis seedlings. In the left photo, the moss is moist and it looks dark – it’s not time to water. With the seedlings in the middle, the moss is lighter in color and it feels fluffy and warm to the touch – It’s time to water.

When to Water Seedlings?

As the moss ages, you may find the sphagnum moss becomes a dark green from algae; that’s okay, it doesn’t harm the plants. You’ll still notice a color and texture change when the aged moss is moist vs. dry. Typically after the moss goes dark like this, you’ll get a sort of jelly-like growth and from that live moss will grow, that’s also okay. Use your POO, (Powers of Observation)–coined by Bill Thoms– to learn when to water and still follow this wet/dry cycle. You will find as the seedlings get larger and the roots become longer, they become a bit more forgiving and resilient; Once they start crowding for leaf space, you’ll be able to repot them into their own pots.

3. Orchid Seedling Growth & Leaf Care

Light & Temperature

I’m going to keep this simple because light can get complicated. If you want your orchid seedlings to grow quickly, you need to provide a good quality light at moderately-high intensity; bright enough for fast growth, but not so intense that it causes chlorosis and not hot enough that it burns the leaves. I have found sunlight in my condo is generally too inconsistent (though it does sometimes work), and that a good-quality full spectrum LED grow light works the best to jam photons into the leaves and help little plants grow faster. I target about 12-30w of good-quality light per square foot of light coverage (but it depends on the type of orchid you’re growing). If you want to know more about light for orchids, refer to this post on the topic.

Regarding temps – orchids grow faster when warmer. So…try to keep your seedlings between 20-25C at a minimum; but as always, look to the requirements of the individual species you’re growing. If you have seedlings of cool or intermediate growers…you don’t want to grow them too warm or you’ll risk killing them. I let my plants go as low as 16c in the winter, but they slow right down, so it’s a case of, “do as I say, not as I do.”

4. Making Seedlings Grow Quickly

Nutrients & Fertilizing

I’m going to keep this pretty simple too because nutrients can get wildly complicated if you get caught up in the details. I use MSU orchid fertilizer at 1/4 strength at every watering because it’s well-rounded and offers both nitrogen and ample micronutirents. I also pH adjust my tap water from 7.9 to 5.8, but that only helps deliver nutrients to the plant more efficiently because my tap water is quite alkaline. You generally don’t have to do pH adjustment…though it might help increase the growth rate a bit. For more about pH, refer to this post on pH and water quality for orchids.

When I pot new seedlings or repot plants, I also use a bit of organic fertilizer (bloodmeal & rock dust) at less than 1/8 tsp per pot. Just a light dusting into the potting mix is all I use. If you plan to use this on your plants, don’t over do it. Organic fertilizers tend to bring bacteria and fungus which are required to break it down and release it to the plant. I feel these can be beneficial to the orchid’s health; however, I have observed that too much can cause issues with the roots. Just a sprinkle is all you need.

 

That covers how I care for my orchid seedlings. Everything in this post is exactly how I’ve been able to grow over 15 different types of orchids from flask; including phalaenopsis, zygopetalum, cattleya, epidendrums, phragmipediums, and mexipediums. If you’ve found this helpful and you want to support me, subscribe to my channel on YouTube and give my videos a few likes. Thanks!

More Photos of My Orchid Seedlings

Epidendrum kockii x Cattleya coccinea on deflasking daySame cross 6 months later And again, a few months after that Mexipedium xerophyticum after a phosphoric acid setback

 

Still looking for more information about deflasking orchid seedlings?

Check out my journal where I tracked my first orchid deflasking experience

 

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