Culture Notes from Brandon Tam's visit to Desert Valley Orchid Society

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Fuzzy bud
Nov 5, 2014
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Colorado, USA
The following information was written by OrchidBoard user estacion seca from a talk by Mr. Tam at the DVOS September meeting. None of the information was written by me, I'm just passing it on. - CambriaWhat

Paphiopedilums the Huntington Way
Brandon Tam - Huntington Botanical Gardens
Presented to the Desert Valley Orchid Society September 21, 2017
Originally posted at by estacion seca

Brandon Tam is the orchid curator at The Huntington Library, Art Collections, and Botanical Gardens in San Marino, part of metro Los Angeles. He gave some of the history of orchids at the Huntington, and spoke on how he grows Paphiopedilums. He also mentioned Phragmipedium, and, briefly, Mexipedium and Selenipedium.

Most of what I write below is directly from Brandon. [I have added a few things] to the history he gave, because his talk was focused on Paphs, and not the history of the Huntington. I have presented the material mostly in the same chronological order Brandon used, but have moved a few things around for greater clarity. Any mistakes will be mine.

History of the Huntington and its orchids
The Huntington is the former estate of Henry and Arabella Huntington. They were members of a family that established railroads in southern California during the initial expansion of Los Angeles. The Huntington has the 5th largest endowment of museums in the US. Arabella was an orchid fancier, among other flowers.

Arabella was first married to railroad magnate Collis Huntington. [She had great taste in art, and collected old masters, medieval and Renaissance works, and French decorative arts.]

After his death she married Collis' nephew Henry, who was also a railroad entrepreneur. Henry collected old manuscripts, including a Gutenberg bible and a first edition of the collected works of Shakespeare. [When he began building his estate in San Marino, the first building was the library. It is still there on the grounds.]

[Henry was fascinated by plants. He established world-class collections of cacti, palms and succulents, which are still on display.] The glass conservatory now on the grounds has the exact footprint of their tropical lath house.

They both loved art, and collected extensively. Henry especially enjoyed English portraitists, and the art collection is rich in oil paintings from this period.

Arabella wore only mourning clothes after the death of her first husband. She established an orchid collection, but only wanted white flowers. Her collection grew to some 20,000 plants. Her favorite flowers, though, were her roses.

Arabella died in 1924. [Henry purchased some of Arabella's art after her death; many other works passed to the Metropolitan Museum of Art in New York, and others were auctioned. A few art works formerly in her possession are still in the Huntington's collection.]

Henry died in 1927. He left his estate in trust to establish the museum it is today. Arabella and Henry are buried in the mausoleum on the Huntington estate. The design of this mausoleum was the inspiration for the Jefferson Memorial in Wasington, DC.

The market crash of 1929 caused financial difficulties even for a museum with a huge endowment. Arabella's orchid collection was sold to a family in France. The Huntington had no orchids for some 50 years, but the remaining gardens have been world famous since their establishment.

The current director of the Huntington Botanical Gardens, Jim Folsom, got his PhD studying orchids. In 2000 he began rebuilding the orchid collection. Eight years ago he hired then-16-year-old Brandon Tam to become curator of a new orchid collection. In 2010 the Paphiopedilum collection of Robert Weltz of Montecito, California, was donated to the Huntington by Weltz' daughers after his death. Weltz was a master grower; among his achievements was a 100-point FCC for Paphiopedilum dollgoldi 'Laurie Susan Weltz'. Mr. Weltz kept extensive and detailed hand-written records on file cards on each plant, including people who had come to see the plant, and where he had sent pollen, and the judging history of each plant.

The Huntington collection now consists of 10,000+ orchids species and hybrid orchids, acquired through donation and purchase. Brandon's plants have earned more than 100 AOS awards in the last three years, including 5 FCC and three CCE. The Huntington received the 2015 AOS Merritt Huntington award for the Most Outstanding Orchid, Paphiopedilum micranthum 'Huntington’s Perfection' FCC/AOS.

Growing Paphiopedilums the Huntington way
[The photos Brandon showed of the Paphs are nothing short of amazing. The plants are enormous.] Brandon does not divide plants unless they fall apart. As a result, many plants are enormous, needing the full strength of 1 or 2 very strong people to lift. [He showed numerous photos of multiflorals with over a dozen bloom spikes and over 100 flowers per plant. He showed a volunteer holding a multifloral plant with leaves reaching almost to the ground; the plant span was at least equal to her height. Many of his multiflorals have leaves at least as long as those of the common California garden plant from South Africa, Agapanthus.]

The Huntington Paphiopedilum greenhouse is over 300 feet long (almost 100 meters) and about 30 feet wide. The floor is concrete. At one end is a wet wall, with exhaust fans on the other. Circulating fans on one long side of the greenhouse are pointed at the wet wall, and on the other long side pointed at the exhaust fans. This maintains constant air movement in the greenhouse.

The Paphs sit in pots on benches. Other kinds of orchids hang from the rafters over the Paph benches to provide shading. The Amorphophallus titanum collection is kept in large pots standing on the floor along the walkways. Their enormous umbrella leaves also provide shading for the Paphs. Brandon has planted some Chinese paphs in moss cusions on flat limestone rocks outdoors in the Chinese garden. They grow well there, and sometimes bloom before they are stolen by visitors.

There are overhead foggers throughout the greenhouse. These are computer controlled to maintain 60% relative humidity.

Temperature is computer controlled at 80 F / 26.5C maximum during the day and 68 F / 20C minimum at night. Cooler growing plants are placed closer to the wet wall, where it will substantially cooler than the rest of the house. Most of the year relative humidity at the Huntington is quite low, and evaporative cooling is very effective.

Misters run along the long sides of the greenhouse. They are on a timer to spray several times per day. Wet-loving plants like Phrags are under these misters.

The Huntington has 3 wells on the property. The well water has from 200-800 parts per million total dissolved solids. Brandon uses this water for the entire slipper orchid collection, including Phragmipedium. [I forgot to ask about Mexipedium.] He does not know what is the pH nor mineral composition of his well water. He does not use reverse osmosis water on the slipper orchids. Brandon recognizes the TDS in his water is far higher than usually recommended for slipper orchids. Most authorities recommend no more than 50 ppm TDS for slipper orchids, including fertilizer, but his plants clearly grow amazingly well. Volunteers regularly clean calcium deposits from pots and leaves.

City tap water was never used until the recent severe drought, when all three wells went dry, and they had to buy city water.

My Green Pets

Fuzzy bud
Nov 5, 2014
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Colorado, USA
Brandon fertilizes the slipper collection with only one product: YaraLiva Calcinit 15.5-0-0. He does not use anything else, and does not add trace minerals. He does not measure nor adjust the pH of his fertilizer solution. He mixes a concentrated solution of 8.61 ounces of fertilizer per gallon of well water (this is 64.5g/l) in a 10-gallon bucket. Then he uses a fertilizer injector at a 1:100 dilution ration to mix this with his well water. He waters the orchids with this solution at every watering. Brandon recognizes the TDS of his well water plus fertilizer is very much higher than normally recommended for slipper orchids, but his results prove his method works.

[YaraLiva Calcinit is sold as a granular fertilizer. The company says it contains calcium ammonium nitrate. I searched and found 50 pound / 22.7kg bags for sale in the US for about $26 at agriculture supply shops. Most cities in the US with a golf course or an agricultural industry will have such shops. Some company names are Ewing, Simplot and Wilbur-Ellis. If people don't want to buy 50 pounds, maybe orchid societies could buy a bag and split it up among members.]

[I looked up the density of calcium ammonium nitrate. It is about 1,100 kg / 1 cubic meter (1,000 liters), which works out to about 1.1g/ml of granules. There are about 28.3 grams per weight ounce. 8.61 weight ounces of fertilizer granules is about 244 grams. The volume of this is about 244/1.1 or 221 milliliters, from the density. 221 milliliters / 5ml/tsp = about 44 teaspoons, or 14.7 tablespoons, to be added to one gallon of water to make the concentrate. There are 16 tablespoons per cup, so this amount is about one cup minus a generous tablespoon. But this must be diluted before use on plants.]

[The SI calculation: 8.61 ounces of granules x 28.3 g/oz works out to about 244g or 222ml of granules per 3.78 liters. This is 64.5g/l or 64.5/1.1 = 58.6ml/l for the concentrate. But this must be diluted before use on plants.]

[The concentrate is diluted 1:100. So the solution used on the plants contains 0.0861 ounces per gallon of water, or about 2.44 grams of granules or 2.44/1.1 = about 2.21ml of powder per gallon of water, a little shy of 1/2 teaspoon per gallon. The SI calculation for the solution used on plants is 64.5g/l or 64.5/1.1 = 58.6ml/l diluted 1:100, so 0.65g granules/l or 0.59ml granules/l.]

[This works out to a nitrogen concentration of about 10 parts per million: 0.65 grams = 650mg, of which 15.5% is nitrogen 650 * 0.0155 = 10.1, per one liter / 1 million milligrams of water]

Volunteers do the repotting and cleaning, but Brandon does all watering himself. He does not water the entire collection at the same time, but waters different plants at different times, based on how the plants look each day. He mentioned dryish plants often have darker green leaves than they do when moist, and he pays attention to how the leaves are held up in the air.

Brandon does not let the plants go dry. He waters 2-3 times per week in summer and about once every 1 1/2 weeks in winter. He waters first thing in the morning, so the plants are never cool and wet, to prevent rot. He doesn't water on cloudy nor rainy days.

Air circulation is critical to preventing rot. Warm, saturated air is the worst for rot risk.

The greenhouse is covered with shade cloth to achieve 1,000-1,500 footcandles of light at mid-day. It is important Paphs receive filtered and not direct sun, or they may burn. Brandon would prefer to use Aluminet shading for the greenhouse, to decrease heating from the sun. However, it can be seen from the Huntington Chinese Garden, and they decided not to use Aluminet for aesthetic reasons. The Chinese Garden is the largest in the world outside China. [And is amazing!]

Rot spreads easily when handling plants. He wears gloves, sterilizes equipment between use and uses cinnamon on plant cuts.

Almost all the slipper collection is potted in plastic, to decrease watering intervals. Many plants intended for display are potted in high-quality terracotta. Brandon has these terra-cotta pots modified: a skilled person drills holes [about 6-8 holes, about an inch, 2.5cm in diameter] in the sides, and the Huntington logo is sandblasted on the rim of the pot.

For some time Brandon has used a mix of 60% Orchiata classic or power size : 20% green chopped moss : 10% sand : 10% bamboo charcoal. Recently he has been trialling 85% Orchiata : 15% large-chunk perlite. He showed photos of the roots on his plants; they completely encircle the pots, and no medium can be seen through the roots when plants are slipped out of the pot.

He showed a video of two strong volunteers playing tug-of-war with a huge multifloral Paph they were trying to divide. The plant did not come apart until one woman cut the rhizome with a clippers.

He pots so firmly the plant can be lifted by the leaves immediately upon repotting, and not come out of the pot. [Of course, the plants have enormous root systems. This would not be possible with a weak root system.] Brandon says it is necessary to pot this firmly, or the roots will not establish against mix that might move in the pot.

He repots before 2 years have passed. The mix is usually not bad by this time, but the plants have outgrown the pot.

He routinely checks the mix of plants, and repots earlier if the mix is breaking down. He tries to push his finger straight down into the mix. If he cannot do so, the mix is still fine. If he can push his finger into the mix, it is broken down, and the plant must be repotted.

Brandon makes self and sib crosses of species only. Plants, seed and divisions are distributed to other botanical gardens. Divisions made when repotting are often given to area orchid societies for auctions.

He made a large enclosed tent from transparent polyethylene landscape sheeting for seedlings out of flask. The humidity in here is much higher than the 60% in the rest of the greenhouse, but there is additional air circulation from fans. He says this helps the seedlings grow much faster than otherwise.

Then he talked about growing specific species or sections. The plants are not placed randomly throughout the house.

The Phrags are along the long walls, where they get automatic misting several times per day.

Parvisepalum Paphs, including Paph. micranthum, are on the benches closest to the wet pad, the coolest spot in the house. Whereas Brandon pots most slippers in plastic, the Paph. micranthum are in clay. This both increases air flow to the roots and cools the roots by evaporation. He said the colder you can keep Paph. micranthum, the better it grows and blooms.

Then next series of benches holds most of the other kinds.

Then come the multiflorals, including many Paph. rothschildianum hybrids. There are fewer hanging plants over these benches, because this group requires more light.

He mentioned Selenipedium to say he does not know anybody growing them successfully. They are very tall, bamboo-like plants. They are rare in the wild, and grow among Sobralias, which are also very tall, bamboo-like orchids. It can be hard to find the Selenipediums among the Sobralias.

Among the many award photos Brandon showed us was a Stanhopea nigroviolacea. [I didn't get the clone name.] An audience member asked how he grows Stanhopeas; he said they are in hanging baskets in the cool greenhouse, kept constantly wet throughout the year, with a drip system that waters them several times per day.

He talked about pests. He uses different products for different kinds of pests, and rotates among 3 or more different products for each pest. He does use neonicotinoids in rotation for insects.

For bush snails he uses a product called Deadline. This is a liquid sprayed on the plant. The snails eat it and die.


Well-Known Member
Jul 17, 2017
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Whoa... up to 800 ppm in the water and then fertilizer on top of that?!?! Crazy. I wonder what the breakdown is in terms of Ca/Mg.

Interesting read!


Orchid Iconoclast
Staff member
Supporting Member
Jun 9, 2006
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Oak Island NC
If you do some digging, I believe he once reported that he only uses calcium nitrate, applies at 600 ppm N (? - better check that; I'm not going to bother).

Yes, extremely high TDS and fertilizer addition, but before anyone starts getting lazy about their own care, we should probably know a lot more details, particularly about the potting media used, as that - especially porosity and drying rate - determines the rate of mineral accumulation. Let us also not forget that the overall growing conditions and frequent watering might be close to ideal, so the "flaw" in the TDS is only one stress, rather than one-of-several.

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