Caring for Phragmipediums Requirements for the phrags species that don't mind high pH

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The following care and culture information applies primarily to the following species (and hybrids of): besseae, fischeri, kovachii, schlimii, caudatum, caricinum, wallisii, boissierianum, longifolium, warscewiczianum, and pearcei. This group of phrags grow along streams or on rocky slopes that are typically more alkaline in nature due to the interaction of rainwater and seepage with limestone (bicarbonate).

Use caution when growing the acid-loving phrags which are native to the North Eastern section of South America where there is a high-prevalence of silica, sandstone, and leaf detritus resulting in acidic (3.5-5pH) and pure water. Specifically beware that lindleyanum and/or klotzscheanum may be more difficult to care for than the other species within the genera.

Video: Phragmipedium Care

Basic Phragmipedium Care & Culture

Watering Phrags

Quick note: The long-long petaled phrags like wallisii, longifolium, and warscewiczianum will differ from the following instructions. These specific phrags don’t like to be kept as wet and should be grown more like the sequential paphiopedilums (constantly moist…but never soggy/wet other than on the day you water).

You want to let the plant sit in about 1/4-1/2″ of water during the spring, summer and fall. In the winter, if your temps are cool (below 17C), you may want to hold off on the water tray and just water as the media starts to dry. At these lower temps, your plant will have a slower metabolism, and fungal problems can be an issue for some growers. Keep in mind, phragmipedium roots don’t want to completely dry out. Approaching dryness is fine, but if your root zone is too dry, the plant will sulk and slow/stop growing and actively-growing root tips will halt/abort.

When you water (should be about once a week), drench the plant and pot; let the water run through the medium and fully flush it out a few times, ideally at least 2 full pots of water should be flushed through the potting media—this helps keep the medium fresh and “sweet.” I cannot stress the importance of running lots of water through the pot, as this action helps flush any hardwater and fertilizer salts and wash away decaying materials. In nature, these plants live with their roots in a constant trickle of water, either at the base of mountains, on river banks or by waterfalls, so they’re used to being wet and constantly bathed with fresh water at the roots. One species, Phrag pearcei is often fully submerged under water! This is a wild pearcei “in situ”:

Water Quality: People claim Phragmipediums are sensitive to water quality and pH…but I have grown all of my phrags in tap water that has a pH between 7.5 and 8 and has a TDS (before fertilizers) of 200-250ppm. In 2018 I started acidifying my tap water, but I still flush the phrags every week with tap water and then I finish with the pH-adjusted fertilizer water.

The areas where these plants grow are rich in lime/basalt and they buffer rainwater to a high pH—I’ve read a lot about “micro habitats” around the root zone caused by mosses that grow on top of the rocks…but have you seen a phragmipedium’s root system? THEY’RE LONG! They reach down and deep…I don’t buy this garbage that moss can locally adjust the pH and out-acidify the buffering capacities of limestone or basalt. Phragmipedium kovachii also require a high pH to grow well; you can read about their care at length, here. I have never had any issues with my phrags grown with our tap water—however, beware I don’t grow some of the sensitive species like phrag lindleyanum or lindenii (which come from habitats that are very acidic and low in minerals).

The most important tips for phrag care: keep their roots continuously moist (or even wet) and beware of the plant’s temperature requirements and limitations—many are cool-growing species that are not tolerant of extreme heat.

Light Requirements of Phragmipediums

Phragmipediums need intermediate light. That means at a minimum an East or West window where they get direct sunlight for about half the day. Be careful though, as the temperature on the leaf should stay below 30•C. If you go above that (if the leaf feels warm to the touch) you may be risking leaf burn. You’ll know if your phrag is getting enough light by the tone of green in the leaves–the should be a bright, vibrant green that has a slight chartreuse color to it. If the leaves are closer to yellow than green, the light is too bright.

Potting Mix for Phragmipediums

When I repot my phrags (which I do as soon as I buy a new one) they get about 1/2 inert material (pumice, perlite, charcoal) and 1/2 degradable materials (bark + sphagnum at a 70/30 split). The higher-level of inert material helps increase air flow through the pot, which is important when you have very wet conditions at the root zone.

If you have a climbing type (besseae are notorious for this), use the above mix and then top-dress the pot with sphagnum moss and mound it up to the bottom of the new growth. Moss will wick water up, and you have to make sure you keep the area where the roots are growing from moist.

In conclusion, if you’re growing phargs, keep them wet, give them ample light, and provide a course medium that allows for airflow through the wetness.

A Quick Note on pH, Alkalinity & Phragmipediums

All of the Micropetalums (besseae, kovachii, schlimii, fischeri, etc) come from alkaline regions. If your water is acidic, you may want to consider adding oyster shells or limestone to your potting mix. You can read more about this in Tony Budrovich’s talk on “Calcicolous Slipper Orchids.” The following excerpt is taken from the AOS Culture sheet on Phrag kovachii by Glenn Decker (which is likely applicable to all Micropetalums because of their similar habitats):

Measurements of the habitat soils are as follows:
• pH lightly alkaline: 7.9
• Electric conductivity: dS/m 0.41
• Calcium carbonate: 85.7 percent
• Organic matter: 1.5 percent
• Phosphorus: 1.9 ppm
• Potassium: 60 ppm
• Water quality of the habitat: pH 6–6.5 E.C. 20 ppm

Medium: As a grower, I think the first of the two most important things to look at is the pH of 7.9, which is really not a surprise when you consider that 85.7 percent of the soil is composed of calcium carbonate, which is the other important factor here. When we first started growing Phrag. kovachii from flask, we planted them out into sphagnum moss, which is what we usually use for phragmipediums. However, we found the plants just sat there, many dying, and others did not grow. This went on for months. Of course, this was before we had all the facts on the habitat. The problem with sphagnum moss, which is on the acidic side, is that it continues to get more acidic as it breaks down. Naturally, with a plant that we now see growing in a pH of 7.9, being more acidic was far from desirable. Since then, we have moved all of our plants to a basic seedling bark mix, but keeping in mind the high content of the calcium carbonate found in its soil. Here is the potting mix I am presently using and we are pleased with its results: 6 parts seedling or fine grade bark, 1 part horticultural charcoal, 1 part sponge rock or large perlite and ½ part of calcium chips or cracked oyster shells

More Phragmipedium Care and Culture Resources You Should Read

Photos of my Phragmipediums