Supplementing Calcicolous Paphs

AnTec Laboratory - Bob & Lynn Wellenstein

A very common question is "I’ve heard Paphs like lime, do I need to add it to my pots or mix?" Like so many ‘simple’ questions, there is no one simple answer.

People often tend to look at Paphs as a homogeneous group of plants, but the fact of the matter is they come from a vast range of habitats, and it is difficult to make generalities as to culture. In the case of Paphs, many grow on or in close proximity to calcareous rock, but at least an equal number do not, and many of these would actually do poorly with a higher pH and calcium/magnesium supplement, so it is important first to know which Paphs tend to have a calcareous substrate in nature. How strongly calcicolous a Paph may be can be inferred to a certain degree from the nature of its relationship with the calcareous rock. Some may be found with their roots in direct contact. Others may grow in accumulated detritus or soils derived from the erosion of the rock, and others, while growing in leaf litter or humus, may still be greatly influenced if they are growing in cracks or crevasses in the calcareous rock, especially those growing below the summit on steep slopes and cliffs, with the water washing down over the stone and into the litter or humus. Plants growing in rapidly accumulating leaf litter on a level forest floor may not be significantly affected by an underlayment of limestone far below. Others are only occasionally associated with limestone (such as Paph. lowii, which is typically epiphytic), and in cultere we do not treat these as calcicolous.We have not determined whether the requirements are for increased calcium and magnesium, or simply the higher pH that results, or all of these factors, but do believe from experience that for the strongly calcicolous species dolomitic limestone supplementation is needed for the long term health of the plant. A few species are also associated with serpentine, which is a basic silicate of magnesium, iron, aluminum, nickel, zinc, and manganese, and a more basic pH is also a consideration for these species.

Secondly, whether to supplement or not depends on the nature of your water and fertilizer. If you already are dealing with high pH hard water, further supplementation would probably be counterproductive. The nature of your potting medium also comes into play. We have always preferred at least a part of the mix to be fir bark for the mixed Paph collection, providing a somewhat acidic base. We feel the ideal situation for the mixed Paph collection is to water with a pure water source supplemented with balanced fertilizer program containing about 40 ppm calcium and 20 to 30 ppm magnesium and a pH in the 6.2 to 6.6 range. This will satisfy the needs of the noncalcicolous Paphs (note there are a few species that will need to have even lower calcium levels, but these are less common). For the calcareous species you would then add, preferably as a top dress to the pot, either crushed oyster shell, pelletized Dolomitic limestone, or Dolomitic limestone chunks. Finer grades of Dolomitic lime or micronized dolomitic limestone are useful for quick corrections, but must be reapplied frequently if not followed by an appropriate supplement. We also prefer to top dress rather than incorporate it into the mix so that we can see when the supply has been depleted and reapply.

You will often hear conflicting views on addition of calcareous materials, but if you explore them they are usually formed based on improper or inappropriate use. On one internet forum recently one person posted that her Paph. delenatii did poorly until she added limestone, and another posted that he saw a bunch of delenatii plants that were covered in limestone and doing very poorly at a nursery. Well, even though a parvisepalum, Paph. delenatii is not a calcareous associated Paph. The first person who saw improvement may have been watering with extremely acid irrigation water, or very low calcium or magnesium levels, and in these cases of poor culture it may have given a boost. In the second case, I’ll bet the plants were in poor shape before the lime was added, and it is very unlikely that the lime helped them, except to a faster demise.

One note on making bark mixes slightly alkaline, they will tend to break down quite a bit faster.

 

Paph. species substrate Chart

Species

calcicolous

Substrate Habit

Measured Substrate pH

Habitat Substrate Comments

Subgenus Parvisepalum

armeniacum

yes

lithophytic, "humus/detritus epiphyte"

7.48 – 7.86

North facing steep limestone slopes

delenatii

no

"humus/detritus epiphyte"

"acidic"

South or southeastern facing mossy crevasses in steep granite cliffs

malipoense

yes

"humus/detritus epiphyte"

7.47

North facing near vertical karst limestonecliffs and steep hills in thin soil and leaf litter

micranthum

yes

"humus/detritus epiphyte"

6.99 – 7.05

North facing near the summit of steep karst limestone ridges, in crevasses in thin soil, mosses and leaf litter

emersonii

yes

"humus/detritus epiphyte", lithophytic

 

Crevasses in northeast facing limestone cliffs, in clay, sand, calcareous soil and humus, or on limestone rocks

Subgenus Brachypetalum

bellatulum

yes

"humus/detritus epiphyte"

 

Cracks and crevasses of limestone outcrops in thin layer of leaf mold and moss

concolor

yes

"humus/detritus epiphyte", lithophytic

7.2 – 8.0

In cracks and crevasses of limestone rock in light humus

godefroyae

yes

"humus/detritus epiphyte", lithophytic

In hollows and crevasses in limestone filled with humus and leaf litter

niveum

yes

"humus/detritus epiphyte"

 

Fissures in vertical limestone where humus has gathered

Subgenus Paphiopedilum

Section Coryopetalum

philippinense

yes

"humus epiphyte", lithophytic

 

Open situations on limestone cliffs, hills and outcrops, piles of limestone rubble

randsii

no

"humus epiphyte", epiphyte

 

Decaying leaves at the base of trees, possibly also epiphytically

sanderianum

yes

"humus/detritus epiphyte", lithophytic

 

Vertical northeast or east facing limestone cliffs

kolopakingii

 

"humus/detritus epiphyte", lithophytic

 

In moss on rocks

stonei

yes

lithophytic

 

On sheer limestone cliffs

adductum

 

"humus epiphyte"

   

glanduliferum

yes

"humus epiphyte", epiphyte

 

Roots in surface humus and soil derived from weathered limestone, rarely epiphytic

wilhelminae

yes

"humus epiphyte", lithophyte

 

Grassy hillsides in clay soil over limestone or on limestone rubble

rothschildianum

no

"humus/detritus epiphyte", lithophytic

 

Ledges on steep slopes of ultra basic (serpentine) rock

supardii

yes

"humus/detritus epiphyte"

 

On limestone rocks in leaf mold filled hollows

 

 

Subgenus Paphiopedilum

Section Pardalopetalum

haynaldianum

rarely

"humus/detritus epiphyte", lithophytic, rarely epiphytic

 

In humus amongst rocks on serpentine cliffs, occasionally an epiphyte – Fowlie

On granite boulders and limestone hills - Birk

lowii

rarely

epiphyte, rarely lithophyte

 

On tree branches and trunks, or in moss or humus filled hollows of rock, especially limestone

parishii

no

epiphyte

 

On moss covered branches

dianthum

yes

"humus/detritus epiphyte", lithophyte

North facing small cliffs and rocks, limestone bluffs

Subgenus Paphiopedilum

Section Cochlopetalum

Glaucophyllum

yes

lithophyte

8

Steep limestone cliffs dripping with water

liemianum

yes

lithophyte

On the roots of trees growing on limestone

primulinum

yes

"humus epiphyte", lithophyte

Humus on limestone hills

On corraline limestone facing the sea

victoria-mariae

no

lithophyte

4.5

Steep wet cliffs of andesite lava

victoria-reginae

yes

lithophyte

Limestone cliff faces with mosses

Sungenus Paphiopedilum

Section Paphiopedilum

hirsutissimum

yes

lithophyte, epiphyte

7.0 – 7.86

Vertical to near vertical, north to east facing limestone cliffs

charlesworthii

yes

"humus epiphyte", lithophyte

On limestone hills and cliffs, roots clinging to rocks

insigne

yes

"humus/detritus epiphyte", lithophyte

Dolomitic limestone outcrops near waterfalls

barbigerum

yes

"humus/detritus epiphyte"

North facing cliff at the foot of a karst limestone mountain

exul

yes

"humus/detritus epiphyte", lithophyte

Attached by its roots to steep limestone cliffs or in pockets filled with humus

henryanum

no

"humus epiphyte"

North facing steep slopes and cliffs

gratrixianum

no

"humus epiphyte"

Vertical riolite bluffs

villosum

no

Epiphyte, lithophyte

Grows in large clumps on branches and trunks of trees, rarely lithophytically

tigrinum

no

"humus/detritus epiphyte"

North facing rocky slopes on steep volcanic mountains

druryi

no

"terrestial"

Steep south east or south west facing rocky slopes…on weathered rock and poor soils

spicerianum

yes

"humus/detritus epiphyte", lithophyte

On limestone outcrops and cliffs

fairrieanum

yes

"humus/detritus epiphyte"

Steep cliffs, outcrops of crystalline limestone, rocks in oak forest, limestone gravels

Subgenus Paphiopedilum

Section Barbata

appletonianum

no

"humus epiphyte"

Deep leaf litter, mossy boulders in sandstone mountains

bullenianum

no

"humus epiphyte"

Moss, deep leaf litter, mangrove roots

hookerae

sometimes

"humus epiphyte"

Deep leaf litter and crevasses in weathered sandstone hills. Also limestone

sangii

no

"humus epiphyte"

masterianum

no

"humus epiphyte"

Leaf litter on steep slopes

papuanum

no

"humus epiphyte"

Among granite rocks in loam

bouganvilleanum

no

"humus epiphyte"

At base of granite outcrop

violascens

no

"humus epiphyte", rarely epiphytic

Found growing in varying conditions, from ultrabasic "soils" to acidic volcanic "soils"

wentworthianum

no

"humus epiphyte"

Light fibrous compost, deep leaf litter

tonsum

no

"humus epiphyte"

Deep humus

argus

no

"humus epiphyte"

Thick mosses and deep leaf litter

barbatum

no

"humus epiphyte"

Leaf litter

callosum

no

"humus epiphyte"

Leaf litter and mossy rocks

hennisianum

no

"humus epiphyte"

Deep leaf litter and humus

fowliei

possibly

"humus epiphyte"

Leaf mold and detritus on limestone rock

lawrenceanum

possibly

"humus epiphyte"

Deep leaf litter, less commonly mossy limestone rock

dayanum

no

"humus epiphyte"

Leaf litter, serpentine outcrops

ciliolare

no

"humus epiphyte"

Forest slopes

superbiens

no

"humus epiphyte"

Steep podsolised ridges

acmodontum

unlikely

"humus epiphyte"

javanicum

no

"humus epiphyte"

Leaf litter among boulders and on banks, leaf litter in cracks between boulders

schoseri

no

"humus/detritus epiphyte", lithophyte

Leafy mold and debris, humus filled rock crevasses, moss covered rocks

urbanianum

no

"humus epiphyte"

Deep leaf litter and humus among rocks

purpuratum

no

"humus epiphyte"

Steep rocky slopes, moss covered banks near streams, deep leaf litter

sukhakulii

no

"humus epiphyte"

Sandy, humus rich loam

wardii

no

"humus epiphyte", lithophyte

On rocks and earth banks

venustum

no

"humus epiphyte"

Cliff ledges above streams, humus rich gullies,steep loamy cliffs, moss covered tree branches



Bob & Lynn Wellenstein
AnTec Laboratory
P.O. Box 65
Candor, NY 13743 USA
607 659-3330
http://ladyslipper.com
copyright 2000 AnTec Laboratory
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