Use Of Coconut Husk Chips for Potting Medium
Bob & Lynn Wellenstein
AnTec Laboratory

Please note that this is an update of our orginal 2000 Coconut Husk Chip article. In this update we would especially like you to note we have changed the washing procedure, our mixes have evolved considerably, and we have incorporated and expanded the CHC FAQ that followed the original article.

To grow a good root system on a Paph you need to balance a number of things. Roots need adequate aeration, firm anchoring (wobbly plants' roots will have their sensitive growing tips
roots
Paphiopedilum Roots  
damaged/destroyed), adequate supply of moisture without remaining too wet too long (which eliminates adequate aeration), adequate and properly balanced mineral nutrition without excess, reasonable temperatures, and a suitable pH in their surroundings. Because paphs do depend on root hairs for water and mineral uptake, it is important to grow new roots frequently as the effectiveness of root hair uptake does diminish with age. I had a discussion on the phone recently with a grower who made the comment " Well, Paphs just don't grow many roots anyway", and then added, "do they?". They can fill the pot with roots when their conditions are met and will do far better for you under these circumstances, as well as be able to weather the occasional problem that may develop. It's entirely possible to grow Paphs, and even flower them with few or even no roots, through foliar feeding and good humidity, but they are much more exacting when it comes to getting them to grow lots of roots. It is also important to maintain new root growth as the root hairs along the roots lose their ability to adsorb water and nutrient as they age, so you need to keep some level of new growth going to maximize uptake. This is why they are "easy to grow, but difficult to grow very well". You need to know
what your water quality is and what it means , and then figure out how much and what to feed, and appropriate pH, and what special needs for substrate some may have.

Like many Paphiopedilum and Phragmipedium growers, we have depended on bark based potting mixes for 20 years. We used small bark, extra coarse horticultural perlite (despite the name, it's pretty small), and chopped New Zealand Sphagnum moss for smaller pots and medium bark, #4 spongerock, and chopped New Zealand sphagnum for larger pots. In more recent years we'd added either #2 or #4 charcoal, depending on pot size. While results have generally been good, there have been a number of problems to deal with. Sequoia brand bark (the only brand we found suitable for Paphs) supply has had some interruptions, and a few years ago the quality was very low, basically being pre broken down before you received it. This spring (2000), after an Executive order setting aside the forest they timbered, Sequoia announced it was ending all orchid bark production mid summer. The #4 sponge rock is only occasionally produced by the manufacturer, so when it became available you would have to scramble to buy as many bags as possible, and the last delivery of 30 bags marked #4 turned out to be #3 and smaller, and extra brittle so that it crumbled into dust when worked with. While the quality of the New Zealand sphagnum moss has generally remained high, there have been periods when it brought along fast growing weed seeds, and the price has gotten quite high. It was also quite labor intensive to wet and cut it into the shorter pieces that were suitable for use in our mixes.

The other major problem associated with bark mixes is their rapid break down. The fine bark mixes are especially prone to this, with noticeable deterioration (with resultant loss of aeration and increase in drying time) in as little as 3 months, and significant deterioration within 6 months under our culture conditions. For a very small collection this is resolvable by very frequent repotting, but in a larger collection this is not feasible. And with the weather conditions found in the Northeastern US where we are located, especially in the winter, we need to maintain a freely draining mix that dries within a few days, when there is less sunlight and somewhat cooler temperatures in the greenhouse.

CHC Bales
Compressed Bales of Coconut Husk Chips  
Anticipating the eventual loss of bark supply, or at least another period of bark quality problems, along with the other problems associated with the bark mix components, we began experimenting with various other growing substrates the past few years. The emerging problems on the US west coast with the oak pathogen, Phytophthora ramorum, and the surveys showing it infects a wide variety of woody plants including Douglas Fir also raised the issue of a possible embargo on west coast bark products, speeding up our plan to find alternate mix components. (This pathogen has been shown to be extremely lethal to the Eastern Oak.) We have worked with rock wool, brick chips, vermiculite, pea gravel, coir, sponge rock, and perlite with varying successes. A couple of observations made are that Paph roots appear to be highly adapted to the conditions they are formed in, and a dramatic shift, even into conditions we might assume to be "better", can cause root loss. If the new medium is indeed better, than you should get rapid new root growth to take over for the ones being lost. Also, if moisture and nutrients are available in "excess" (i.e. in a dense mix), then the plants will grow far fewer roots, as they need less root mass to supply themselves. But, in these denser mixes, they are more prone to root loss, especially if warm conditions are not maintained at the root zone, and having fewer roots to start with, even minimal root loss can be critical. As a result, it is our goal to grow plants under conditions that encourage maximum root mass, as these plants will be far less affected by a problem resulting in the loss of some roots (i.e. being allowed to go too long before repotting with resultant mix breakdown or a period of overwatering), and in our opinion result in more robust plants and better flowering. In almost all of the components we worked with, there seemed to be a universal constant inverse relationship between the air capacity and the water capacity. In other words, a mix that drained freely and allowed enough air into the mix immediately after watering held insufficient water for Paphs and Phrags, those that held sufficient water allowed for insufficient air. Other aspects of the components that we felt were important were the ability to anchor the plant in the pot without and wobbling when watered or handled, to avoid damage to growing root tips, stability over time both with respect to aeration and water holding and pH.

small CHC
Hydrated Small Coconut Husk Chips  
Two medium components did defy logic and have the capacity to hold large amounts of air and water simultaneously. The first is New Zealand sphagnum moss used alone. NZ sphagnum will simultaneously hold more water and more air than almost any other potting medium commonly available if kept loosely packed, but therein is one problem: overpack it or allow it to pack itself overtime and it holds way too much water and too little air. NZ moss does have some drawbacks: it is also hard to stabilize a plant in its pot with a loose pack of moss, it is hard to rewet if allowed to completely dry out, and does break down fairly rapidly if kept moist, so for some folks its a wonder medium, for most it's not very practical. It is also a very acidic medium, and retains this property for a long period in spite of heavy watering. When it loses this acidity is when it breaks down very rapidly. Our experience is that it is a very good medium for temporary root recovery culture (particulary live sphagnum moss) of the acid substrate Paphiopedilums, but we have not found it to be particularly good for long term culture.

The second was coconut husk chips. While holding approximately the same level of air immediately after watering and as it dried out over a 5-day period in 2.5-inch rose pots; it also held substantially more water. After six months under greenhouse conditions, fine fir bark had broken down and dramatically lost its air holding capacity and stayed quite soggy, while the small coconut husk performed essentially as it did when new. We'll discuss some quantitative aspects of coconut husk chips later in this article, but first lets discuss its preparation, use, and some of our qualitative observations.

medium CHC
Hydrated Medium Coconut Husk Chips  
Let's make completely clear what we are referring to, as there are several coconut products for potting on the market. What we are using are chunks of the husk, cut to surprisingly uniform size. The three sizes available correspond quite well with the sizes of Sequoia bark. Other coconut products include coir, which is ground up husk, coconut husk fibers which is a stringy material made by somehow "unraveling" the coconut husk, and coconut husk charcoal.

We use the compressed bales of coconut husk chips from Crystal Company of Saint Louis, Mo. or Roberts Flower Supply in Ohio. These have been prewashed and pressed by the company a couple of times to reduce the amount of leachable salts contained in the product, which can vary greatly and be quite high from some sources. They are both Sri Lankan sourced, which appears to be better quality than other sources. When hydrated, each bale will swell to about 6 to 7 cubic feet of husk, so we divide each bale into two 32 gallon containers (plastic garbage cans) for hydration. The coconut husk from these bales has been extremely clean with relatively little dust, and quite uniform in size. There will be a small amount of fines after hydration, but the amount has been so small as to present no problems.

CHC Washing
Washing Coconut Husk Chips  
To prepare the husk we first hydrate the bale in two 32 gallon containers at least overnight , and then transfer the hydrated husk and excess water to a second container that has had a large number of holes drilled into the bottom, and about six inches up the sides. After the husk drains, a steady stream of water is washed through until it appears to run clear from the container. Then the husk is again transferred back to the solid container and again covered with water with a few ounces each of Calcium Nitrate and Magnesium Sulfate (Epsom Salts) added at least overnight. The draining and washing procedure is repeated again using pure water, with the final rinse being extensive. At this point measurements have revealed virtually no significant leachable salts and a pH just slightly below neutral. The conditioning with calcium and magnesium is done because of the moderate Cation Exchange Capacity (CEC) of the coconut husk. Sodium (Na) and Potassium (K) ions are strongly bound to the CHC. Laboratory comparative analysis of extracts of coconut husk products using distilled water versus a barium chloride solution demonstrate that as much as 2/3 of the Na and K may not be leached by water alone. What then happens is that you cation exchange calcium and magnesium for sodium and potassium in your early fertilized irrigations, creating possible calcium and magnesium deficiencies and sodium and potassium excesses. If you irrigate heavily as we recommend, the problem is quite temporary and limited. Unfortunately, it seems to be more and more common to hear about people using less extensive irrigation practices, and under these circumstances problems may arise. The addition of calcium and magnesium in the wash stages allows for cation exchange to occur then, creating a more balanced state from the start.

Coconut husk can be somewhat firmly packed in the pots, but not tremendously so, as it has a springy substance, and will change slightly in size as it loses water and then is rehydrated. It hydrates very rapidly, even from the completely dry state, and essentially instantly from the partially hydrated state it would be in your pot when you water it. It contains the water within itself like a sponge: if you squeeze a piece that is even partially hydrated, water will come out of the cut fiber end even when the outside of the husk appears dry. The exterior of the husk chips does dry very rapidly when exposed to air flow, so the tops of the pots appear to dry out very quickly, but just 1/2 inch further down their can still be a considerable amount of moisture. This takes a little getting used to in judging when to water, but has the benefits of discouraging fungus gnats (the larvae tend to live in the top 1/2 inch of the medium and prefer very moist conditions) and lessening the chance of rot starting in the lower leaf fans, especially if they are potted slightly lower than they should be. We have noticed in our smaller (2.5 inch) deep pots that over the period of a year or so the "loft" of the mix will actually increase, sometimes necessitating "flicking" a little bit of mix off the top of the pot to get it back to the correct level for the base of the plant.

small aliflor
Sponge Rock  
We add #4 Sponge Rock and #2 charcoal to the husk. Our current formulas, which are continually being experimented with and tweaked, are listed later in the article. We have eliminated the use of Aliflor completely, but #3 diatomite is added for larger pot sizes, the amount based on the pot size and root system and needs of the plant being potted. My scientific background makes me wish to be able to give a quantitative or at least sound theoretical reason for the addition of the charcoal, but I do not have one. Lynn's observations have convinced her it is a valuable addition, and I have learned that her observations are uncannily accurate, even when they might go against logic (more on this later).

roots adhering to CHC
Newly Emerging Roots Adhering to the Coconut Husk Chips Just a Few Weeks After Repotting  
When we first started experimenting with coconut husk chip mix on some plants, we would unpot a portion of them every week to inspect the roots. We were impressed at both the speed of initiation and the number and substance of new roots on the plants that had been switched. We continue to see this, and have been working to switch all plants, from seedlings to stud plants, over as quickly as possible to this new mix. We have repotted several plants that had lost all of their roots while in our standard bark mix and were "circling the drain" into coconut husk chip medium and have watched them revive and initiate new roots faster than we would have believed possible for a Paph to respond to such improved conditions. A few plants that we feel would have otherwise have certainly died due to their poor root health have been revived using this new mix. We have also seen a similar pattern in our Phrags. While it is much easier to maintain good root systems on Phrags than Paphs, our Phrags seem to have immediately picked up when put in coconut husk, perhaps due to the greatly increased reservoir of water contained within their pots while still maintaining a high degree of aeration. Our Phrag. besseaes, which have always suffered with the summer heat and have had to go under the bench for the summer in the past, have spent the entire summer on the bench top in very bright light and heat, and are not showing any of their usual summer stress signs. However, we have found that our moisture loving Phrags perform even better potted in pure #3 Diatomite sitting in circulating aerated water. Two keys to this modification in culture are having a virus indexed Phrag collection and keeping the water acidic. Prelimary experimenting with this system seems to indicate that leaf tip die back in Phrags is more related to pH than to salt concentration. We have also switched some root distressed Phals (with some different proportions of medium components, including a greater percentage of Sponge Rock) over with the same response as the Paphs and Phrags-- near immediate and vigorous root growth. It also appears to be working well with our agar-on compotting technique for both Paphs and Phrags.

One of the most encouraging signs that the plants like the coconut husk chips is that when we unpot them, all of the new roots are attaching themselves firmly to the cut fiber end of the husk chunks, as if they are seeking out their personal water and nutrient reservoirs. While we would find roots attached to bark chunks also, it occurred at no where near the rate it does with the husk chunks.

bark vs CHC fresh
Comparison of Air & Water Holding Characteristics of Fresh Bark and Fresh Coconut Husk Chips  
Perhaps the most valuable improvement coconut husk chunks offer over bark is its resistance to breakdown and ability to maintain its characteristics over a long period of time. Coconut husks durability stems from having a lignin content five times that of bark, and the other components we use, aliflor and charcoal, also have quite good resistance to breakdown. The data and charts presented here for fresh media components, and a comparison of fine bark and fine coconut husk chips as a fresh product and after 6 months of greenhouse conditions and a watering, offer a striking difference between the two. The bark and coconut start out essentially the same, both with excellent aeration characteristics and with the coconut husk at an advantage in water capacity, but within six months in a pot in the greenhouse with regular watering, the fine bark has rapidly broken down, holding way too much water and not drying out, all at the expense of its ability to hold air. The coconut husk is still performing essentially the same as it did when fresh. After a few years experience we use the smaller grade of CHC only for seedlings and compots, as it does start to break down under our conditions after 12-18 months, while the medium grade holds up much better.


bark vs CHC at 6 months
Comparison of Air & Water Holding Characteristics of Bark and Coconut Husk Chips After 6 Months of Greenhouse Use  
As a result there will be far fewer complications when using coconut husk fiber if repotting is delayed, in fact we feel the only reason for annual repotting when using it will be to pot up because of the vigorous root growth we see with it.

The chart following details some experimental findings with various mediums and medium components. All of the data was collected using 2.5 inch SVD "rose" pots (deeper than they are wide) in our greenhouse conditions. Relative humidity was in the 70% range during the test, with daytime temperatures in the low to mid 80's and night time temperatures in the mid 60's. The capacity of this pot is 246 cubic centimeters; the numbers listed in the first chart show the cubic centimeters of air and water retained in the pot with various mixes and mix components immediately after a thorough watering and then at the intervals listed.






Days Post Watering --->

immediately

1 day

2 days

3 days

4 days

5 days

 

after watering

         

Paph Seedling Mix - air cc

126

145

151

154

160

164

Paph Seedling Mix - water cc

72

53

47

44

38

34

Phrag Seedling Mix - air cc

133

144

154

158

165

171

Phrag Seedling Mix - water cc

83

72

62

58

51

45

Adult Large Paph Mix - air cc

135

152

158

162

169

174

Adult Large Paph Mix - water cc

80

63

57

53

46

41

Med Aliflor - air cc

124

141

145

148

153

155

Med Aliflor - water cc

31

14

10

7

2

0

Small Aliflor - air cc

108

122

128

131

136

141

Small Aliflor - water cc

45

31

25

22

17

12

Small CHC - air cc

130

141

145

148

152

159

Small CHC- water cc

68

57

53

50

46

39

Med CHC - air cc

130

147

154

160

165

174

Med CHC - water cc

98

81

74

68

63

54

Med Bark - air cc

143

165

168

170

173

176

Med Bark - water cc

37

15

12

10

7

4

Small Bark - air cc

127

146

149

151

154

158

Small Bark - water cc

46

27

24

22

19

15

Large Char - air cc

122

132

137

140

143

148

Large Char - water cc

49

39

34

31

28

23

Small Charcoal - air cc

107

115

118

120

123

126

Small Charcoal - water cc

38

30

27

25

22

19

Small Stones - air cc

114

122

128

130

134

138

Small Stones - water cc

28

20

14

12

8

4

#3 Spongerock - air cc

137

164

171

177

183

189

#3 Spongerock - water cc

52

25

18

12

6

0

Hort Perlite - air cc

115

132

139

144

151

155

Hort Perlite - water cc

91

74

67

62

55

51

NZ Sphag - air cc

136

162

176

192

201

210

NZ Sphag - water cc

87

61

47

31

22

13

6 mo old bark - air cc

96

113

118

123

127

130

6 mo old bark - water cc

114

97

92

87

83

80

6 mo old coconut husk - air cc

131

141

146

150

154

159

6 mo old coconut husk - water cc

70

60

55

51

47

42


Notes on above chart:
Mixes - see formulas below
CHC = Coconut Husk Chips
Bark is Sequoia Brand
Large Charcoal = #2
Small Charcoal = #4
Small stones = #1A crushed sandstone
Horticultural Perlite = extra coarse
New Zealand Sphagnum = a loose pack of long fiber moss

The following chart presents the same data as the percent of total volume of the pot:

Days Post Watering --->

immediately

1 day

2 days

3 days

4 days

5 days

 

after watering

         

Paph Seedling Mix - air %

51

59

61

63

65

67

Paph Seedling Mix - water %

29

22

19

18

15

14

Phrag Seedling Mix - air %

54

59

63

64

67

70

Phrag Seedling Mix - water %

34

29

25

24

21

18

Adult Large Paph Mix - air %

55

62

64

66

69

71

Adult Large Paph Mix - water %

33

26

23

22

19

17

Med Aliflor - air %

50

57

59

60

62

63

Med Aliflor - water %

13

6

4

3

1

0

Small Aliflor - air %

44

50

52

53

55

57

Small Aliflor - water %

18

13

10

9

7

5

Small CHC - air %

53

57

59

60

62

65

Small CHC- water %

28

23

22

20

19

16

Med CHC - air %

53

60

63

65

67

71

Med CHC - water %

40

33

30

28

26

22

Med Bark - air %

58

67

68

69

70

72

Med Bark - water %

15

6

5

4

3

2

Small Bark - air %

52

59

61

61

63

64

Small Bark - water %

19

11

10

9

8

6

Med Char - air %

50

54

56

57

58

60

Med Char - water %

20

16

14

13

11

9

Small Charcoal - air %

43

47

48

49

50

51

Small Charcoal - water %

15

12

11

10

9

8

Small Stones - air %

46

50

52

53

54

56

Small Stones - water %

11

8

6

5

3

2

#3 Spongerock - air %

56

67

70

72

74

77

#3 Spongerock - water %

21

10

7

5

2

0

Hort Perlite - air %

47

54

57

59

61

63

Hort Perlite - water %

37

30

27

25

22

21

NZ Sphag - air %

55

66

72

78

82

85

NZ Sphag - water %

35

25

19

13

9

5

6 mo old bark - air %

39

46

48

50

52

53

6 mo old bark - water %

46

39

37

35

34

33

6 mo old coconut husk - air %

53

57

59

61

63

65

6 mo old coconut husk - water %

28

24

22

21

19

17


There is a lot of data presented here, and a lot of information can be gained from its careful analysis, but goes beyond the scope of this article. One important point I would like to emphasize is that the data on a mix component gathered from testing it alone will not always be predictive of its behavior as a minor component of a mixture of components. A case in point was experimentation with the # 1A sandstone. Lynn had made the observation that when they were added to the CCH mixes, even in fairly small amounts, that they caused the mixes to dry out more slowly. I didn't feel this made any sense, as they held very little water themselves, and suggested that it was just an illusion due to the increased weight of the pots. However, when the mixes were tested, it turned out to be true that the mix with stones dried out more slowly than that without. As a result it is now used only with the Phrags.


Several questions have arisen about the use of Coconut Husk Chips (CHC) that we felt would be best answered in a follow up.

First, all Coconut Husk Chips are not all the same, and the product we are using and recommending is not the same product that was available several years ago, and is indeed different from many others that are now on the market. The CHC we are suggesting for use has been washed and pressed three times prior to drying and being compressed into bales for sales. This accomplished a few things, the main one being to greatly reduce the initial salt load of the husk. As our article points out, we still do 3 washes (including the cation exchange) to further eliminate salts since we deal with what we consider to be sensitive genera. The importer (Crystal Corporation of St. Louis) also believes that the pressing opens the fiber up a little and that this makes it a better product. At this time, we have not tested CHC from any other sources. I have been asked about several, but we cannot answer about their use as we have no experience with them yet. I have been contacted by one supplier who said he had exactly the same product, but when I asked if he could say with certainty that it had been pressed and washed three times I did not get an answer. I do understand that he has since told others yes, so perhaps he has been able to clarify that situation, and if so I'll obtain some bales from him and test them, and if they prove equal will list them as another source. It is my understanding that even the loose bags of coconut husk chips from Crystal are not at this time the same as the washed and pressed bales, therefore I would certainly ask them about the product and its processing before purchasing. The point of this is, if you tried CHC a few years back, this is a somewhat different and decidedly better product.

We've also been careful to be clear about what Coconut Husk Chips are, but I see through questions and online forums that there is still a lot of confusion regarding CHC versus coir. Coir is a very different product from CHC, as it is basically finely ground coconut husk, whereas the CHC is cut to fairly uniform pieces that are available in three sizes similar to the old Sequoia bark. Coconut Husk Chips would be analogous to Sequoia bark, whereas coir would be to peat.

It is also important to remember that you should adjust any mix to your growing conditions, pot sizes, light intensity and heat availability, and genera grown. We currently use two sizes of CHC and amendments consisting primarily of sponge rock, diatomite and charcoal, with extra coarse vermiculite and perlite for smaller plants and compots. Some folks can grow quite successfully under certain conditions in pure CHC, others, because of their different circumstances in growing, need to amend the mix (i.e. add either more or less CHC, or more or less sponge rock or light aggregate) to alter its air and water holding characteristics, and its drying characteristics. We listed the current mixes we are using, but indicated that they no doubt will undergo some alterations as we move along and gain more experience with the CHC mix under our conditions. There is nothing magical about these formulations, they are just the best combination we have discovered to date that works for us. While we use a pretty standard formulaation for a given pot size for seedlings, we can actually custum tailor the mix slightly for larger pots of stud plants. This is basically a case of one size does not fit all. We've communicated recently with folks using other mixes that were losing plants after bringing them indoors (not potted in CHC) from growing outside over summer. After some questioning it was determined that they were basically all potted as a "one size pot and mix fits all", and outside the plants got along okay, but then when put back under the HID lights, three to four days after watering some pots were bone dry and some were still wet. Some repotting in different size pots to suit the size of the root system (and not the size of the top growth) and mixes more suitable to the underlight condition will hopefully remedy this situation. It should be noted that plants under fluorescent lights will dry out considerably faster than those growing under HID, due to the heat generated by the former, and the plants generally being placed much closer to the light source (several inches versus several feet). Thus, plants grown under fluorescent lights may need less Aliflor, while those grown under HIDs may need more Aliflor. If you are careful it is possible to gently unpot the plant if you are not sure how well it is growing, and this will allow you to check the root system to see whether there are any new roots tips forming.

There also have been lots of questions about water and water retention. A couple of points are important to remember here, the first perhaps being that air capacity is at least the equal part of the equation for avoiding root rots, and CHC is at least the equal in air capacity of the same size bark, and retains this capacity while bark starts to break down rapidly, losing air capacity and increasing water capacity. You can also, of course alter the air and water capacity of the CHC mix with the use of the amendments, and this is what we suggest you do to customize the mix to your plants, conditions and how they are growing for you. Another variable is how the CHC holds the water, much more within the center of the fiber chunk, and drying on the surface, as opposed to bark which tends to hold more at the surface. Having said all this, we do believe that the CHC mixes are much more forgiving either of slight over or underwatering habits than the same bark mixes. Again, I think this has a lot to do with the excellent air capacity of the medium. As we all know, Paphs and Phrags grown in bark mixes seem to get a real boost after a repotting, in spite of the shock to the roots, and this again tends to point to the importance of good air supply to the roots, which the CHC seems to maintain at or near its original level for substantially longer periods of time than bark. There is some relearning of when to water the CHC mixes; they do dry differently, particularly at the surface of the pot where they dry much faster. (We have been fooled more than once while watering the seedling house, thinking we completely missed a bench, when in fact the surface of the CHC mix has simply rapidly dried while we were watering the other benches.) We also think it is at least as important if not more important when using CHC to be aware of the total salt concentrations of your irrigation mixtures, and to water very generously and flush periodically, not only to reduce salts, but because of the increased capacity of the CHC to adsorb and hold water. Water thoroughly! Alter your mix to suit your conditions!

The pH of the CHC mix we use is also closer to neutral than bark mixes, and this has been useful in allowing us to control the pH of our root environment closer to what we desire. However, it may affect the point to where you adjust your irrigation water, just a point to keep in mind. Most Phrags, with perhaps the exception of (Mexipedium) xerophyticum, seem to like acidic conditions, while the Paphs tend to be a group split between those that grow in somewhat acidic conditions and others that grow in calcareous or other basic rock substrate.

It's been suggested that the CHC mix is suitable only for higher heat conditions found in Florida or California. Candor, NY is not the tropics, with nearly six months of dark and chilly winter, and while we maintain a modest minimum winter temperature in the greenhouses, a simple adjusting of our watering schedule allows the CHC mix to perform admirably. Again, it is a matter of making the appropriate adjustments to the mix, one size pot or one type of mix does not fit all conditions. We feel that you can probably use and get better results from CHC for anything for which you would use a bark mix, you just have to perhaps make up the mix a little differently. In warmer conditions, we suspect you may be able to use CHC where bark is unsuitable due to rapid breakdown, and even under our cooler conditions it is superior also because it does not change characteristics rapidly (note in the article how fast fine bark breaks down even in our northern conditions).

We repotted several plants that were growing poorly in our old bark mix (and were found to be suffering considerable root loss) into the new CHC mix and were amazed by their response and rapid revival. These were plants that were past the point where they would have been invigorated by normal bark repotting, they were basically close to dying, and we firmly believe that repotting in our previous bark mix would not have achieved the same response.

We feel that Paph and Phrag roots are very highly adapted to the medium they grew in, and a dramatic change can quickly cause minimal to moderate loss of roots. We have seen some very well rooted plants formerly grown in bark suffer some initial root loss in the CHC mix, but then an immediate flush of new growth begins with those lovely white tips forging their way out of the base of the plant. There is no doubt in our mind that this is a much superior mix for us than bark, and believe that anyone using bark, and approaching CHC use with the above considerations in mind, will probably see similar results. It is helpful to remember that everyone's' growing conditions are different, and that one mix will not work for everyone. Watch your plants, pay attention to detail, and if in doubt, unpot and check your roots. Your plants will thank you for the extra attention and will reward you with superior growth and flowerings.
Mixes Currently in Use

Note on the Paph mixes that if they are to be used for calcicolous or ultrabasic growing Paphs, a layer of crushed oyster shell is added to the surface of the pots. Please also note, these work for us. Adjust or alter to suit your conditions.

Paph Seedling Mix (2.5 inch pots and under) and compot mix:
3 parts small CHC
2 part #4 sponge rock
1 part extra coarse vermiculite
1/2 part #2 diatomite
1/3 part horticultural perlite

Adult Paph Mix 3 inch pots and up:
6 parts medium CHC
3 parts #4 sponge rock
1 part #2 charcoal
#3 diatomite added on individual basis

Phrag Mix (wetter growing Phrags):
#3 diatomite
Placed in 3/4" circulating water

Phrag Mix (caudatum types):
#3 diatomite
watered from above as needed

Bob & Lynn Wellenstein
AnTec Laboratory
P.O. Box 65
Candor, NY 13743 USA
607 659-3330
http://ladyslipper.com
copyright 2004 AnTec Laboratory
May be reproduced by nonprofit organizations if presented in it's entirety.

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