OrchidSafari ARCHIVES*

1. PRE-DISCUSSION MAILOUT

2. TRANSCRIPT

PRE-DISCUSSION MAILOUT

ORCHID ROOTS - Just what functions do they serve?

- Roots anchor a plant.
- Roots absorb water and mineral nutrients.
- Roots form associations with mycorrhizal fungi.
- Roots store starch and water.
- Roots of certain leafless orchids fulfil the role of leaves.

ROOTS - Why must we conserve roots when repotting an orchid?

- Roots are important organs of absorption. Damage the absorptive surface and you risk damaging the absorptive capacity of the root.

Water and minerals are absorbed by delicate root hairs, tiny thin-walled structures protruding from the root. New root hairs are continuously produced a distance behind the growing point. Root hairs are also the point of access for mycorrhizal fungi. The fungi grow both in the potting medium and into the root. The orchid is able to digest the fungus within the root cells and thus derive nutrient from it. The fungal net may be an important harvesting network for water and minerals.

- Roots are important storage organs.

Many orchids use the roots to store reserves. Removal of many roots reduces the food and water store of a plant. Without this storage capacity, a plant may need perfect growing conditions and much time to be able to recover.

ROOTS - How can we promote root growth?

- With orchids that grow year round such as Phalaenopsis, nutrients and water are stored in the roots and the leaves. Grow such plants in humid conditions at a temperature appropriate to the type. Vary the temperature from day to night. Fertilize regularly with a diluted formula containing micronutrients. Flush the potting medium at least monthly to counter salts buildup. Excessive mineral salts in the medium will suppress root growth.

- With orchids that grow seasonally and produce pseudobulbs such as Catasetum. Nutrients and water are stored in the pseudobulbs: leaves are deciduous. Re- pot, water and feed the plants when they begin to grow new shoots and roots, continuing until the pseudobulbs are at their maximum size. Allow for lots of root growth in the container. The more roots the plant produces, the larger the pseudobulbs and the more flowers and spikes you can have.

- With orchids that grow seasonally and do not produce pseudobulbs such as Stenoglottis. These orchids store water and nutrients in succulent roots: leaves are deciduous. Once a new shoot appears, re-pot, water and feed the plants to promote extensive shoot growth. Provide bright, filtered sunlight. The larger the rosette of leaves, the more starch that can be stored in the roots and the more substantial the inflorescences that will develop later.

FERTILIZERS - Where is the magic?

Each plant has a particular maximum growth potential which cannot be easily surpassed. Plants use light energy to grow but cannot be forced to grow faster simply by providing more light. Mineral nutrients are needed to support growth and development but cannot replace light as a growth promoter. A balance is needed between 1) a particular growth potential; 2) the quantity and quality of available light; 3) the quantity and balance of mineral nutrients; and 4) water. Roots must be alive and growing if they are to absorb nutrients.

If we choose to grow a plant with a high growth potential such as Cymbidium, then we must satisfy all parts of the equation for growth. There must be plenty of water, regular applications of fertilizer and adequate light to control the burgeoning growth. Too little light and soft, floppy growth will result. Too much light and fertilizer but not sufficient water and roots will suffer. We want to foster optimum growth of pseudobulbs, leaves and roots because this in turn will support the production of flower spikes.

Plants can only use what they need to support growth. Excess fertilizer is not stored in any great quantity and is wasted. Better regular applications of dilute preparations than infrequent applications at high dose. There is no magic but there is the value of patience and perseverance.

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TRANSCRIPT

Wed, April 14, WBS 8 PM (Central)
Conservation Series (Part 22) with Marilyn Light
TOPIC: At the Root of the Matter: fertilizers and potting media

Present were 13:

marilyninOttawa
Ellen,Smithtown,New York
nodosa (Ed in SAT)
marylois (northwest Louisiana)
UncleEarl (Earl from Vacaville, CA)
poln8r (Robert from Long Beach, MS
JanetteH (beautiful day in Pilot Mtn., NC)
jim4eq (hot humid miami)
AORCHID (art, simpsonville sc)
Jane5536 (Huntington L.I. N.Y.)
kbbarrett (Kathy in N Calif)
55SS (James in Fresno)
gaillevy (Boca Raton, Fl)

marilyninOttawa
I hope we can discuss how roots function and how to go about caring for our orchids such that the roots are conserved.

marilyninOttawa
Earl, would you agree that Brazilian Miltonias are a good example of an orchid that produces roots year round?

UncleEarl (Earl from Vacaville, CA)
Yeah, Marilyn, though they do slow down in the winter some.

marilyninOttawa
Good point, Earl. I try to repot or divide such orchids when they are in active growth. Even severed roots will branch out.

UncleEal (Earl from Vacaville, CA)
Usually there's a period of rapid root growth just after new growth starts, as I recall, usually in the early spring. Always repotted then. Repotted *everything* when new roots started; always seemed to work best for me.

nodosa (Ed in SAT)
I doubt Vandaceous orchids ever stop root growth. We sometimes crack the velamen to make them branch vs elongate, but they seem to keep producing ropes no matter what.

poln8r (Robert from Long Beach, MS..
I try not to cut or break roots, even tho some folks I know do it and get good results. I don't want to open a place for disease to enter. Besides, if the root is good, I want to keep it.

marilyninOttawa
Very good point, Robert. Cut or crushed roots can give a place for disease to enter. We must be especially careful of damaging roots of orchids that have few roots or that grow only seasonally.

marilyninOttawa
Earl, do you grow the Miltonias in pots or on mounts? I have grown mine on tree fern slabs as it accommodates the rampant growth of some cultivars. Most I grow in plastic pots with coconut coir/bark chips as my preferred mix. Copious roots are produced and this is reflected in the bountiful growth above.

UncleEarl (Earl from Vacaville, CA)
The Brazilian I grew in pots, for the most part, with medium to med-fine charcoal chunks. Lot of them were planted out on Hapu'u trees as well. Loved it.

marilyninOttawa
Hapu'u is treefern, right?

JanetteH (beautiful dayninOttawa
What is an Ohi'a Earl?

marylois
How about mixing the powder in vaseline? (You could do that: commercial products are blended with lanolin. I choose the latter as it is cheap and less mess. ML)

UncleEarl (Earl from Vacaville, CA)
Ohi'a - a tree (Meterosideras collinia, I think), native to the Hawaiian Islands, with 'bottlebrush'-like blooms, colored from the usual red, through orange, yellow, to white (*Very* rare).

AORCHID (art, simpsonville sc)
Does Oncidium splendidum need a rest period after it blooms? Does it produce roots with new growth?

marilyninOttawa
Onc. splendidum grows seasonally: the roots are quite coarse. The plant does not require a firm rest, it simply will not resume growth until it is ready to do so. I have grown it in tree fern fiber and charcoal in a clay pot. I love this plant even when not in flower.

marylois
Have splendidum in a basket too. *G*

UncleEarl (Earl from Vacaville, CA)
Medium, ML?

marylois
Basket lined with hardware cloth and filled with my charcoal mix (charcoal with perlite, pro-mix, treefern)

55SS (James in Fresno)
How does ampliatum do in a basket?

Clare in LA
Lois, what's hardware cloth?

JanetteH (beautiful day in Pilot Mtn., NC)
Superthrive... Doesn't that promote root growth? Have a question for all of you math experts out there. If you use Superthrive at the rate of 1 drop/gal., how much do you put in a gal if you are using a dosamatic at 1:100? If you are lazy and don't want to count 100 drops?

marilyninOttawa
I wouldn't recommend mass spraying with Superthrive-type products. I believe that the rate of 1 drop per gallon is something like 1:80000 dilution and just not possible to manage using the Dosamatic.

poln8r (Robert from Long Beach, MS..)
Hardware cloth is that 1/2" or 1/4" square screen. Usually galvanized.

UncleEarl (Earl from Vacaville, CA)
Half by half, or quarter by quarter, gavanized wire mesh; just ask at the hardware store and they'll show you. If you are growing the pendulent ones,like Stanhopea's, use a larger (like 1 x 1 or larger) mesh size. Lets the spikes emerge.

JanetteH (beautiful day in Pilot Mtn., NC)
Some people call it rabbit wire...at least around here.

marylois
Stanhopeas are in those wire baskets with no horizontal wiring - I line 'em with sphagnum, put in plant, fill with media.

JanetteH (beautiful day in Pilot Mtn., NC)
We have tried about the same thing, Lois. We buy the baskets with the coconut liners and cut out the bottom half of the coconut liner. Then line the bottom half of the basket with sphagnum. The stanhopeas seem to like it.

poln8r (Robert from Long Beach, MS..)
Janette, that would be 100 drops, right? Put 100 drops into something that you can measure and then just use that amount.

marylois
A pharmacist could tell you how many drops make an ounce/or half ounce - or barring that - give you a hypodermic to measure cc's.

kbbarrett (Kathy in N Calif)
Janette, 20 drops used to be 1 cc liquid. so thats 5 ccs. Hmmm, 5ccs should be one tablespoon.

[...or a dentist *G*...mlg]

JanetteH (beautiful day in Pilot Mtn., NC)
I have a bunch of little paph seedlings that I was thinking about using it on, Marilyn. How do you recommend applying it?

poln8r (Robert from Long Beach, MS..)
How big are the Paph seedlings, Janette?

JanetteH (beautiful day in Pilot Mtn., NC)
3 to 5 inch wing span. Have taken them out of compots beginning in January and they don't seem too happy.

poln8r (obert from Long Beach, MS..)
I just put 'em in a 1-1/2 or 2'' pot and treat them like everything else in a small pot. Maybe a little extra water for a week or two 'cause the bark dries fast.

marilyninOttawa
When I apply Superthrive it is only at the deflasking stage. Then I dilute the 1 drop in a gallon and lay the deflasked seedlings in the solution for a few minutes before planting up. You could mix the Superthrive in a bucket then water the seedling trays with the solution. The solution is so dilute that two or three applications, one after the other will not hurt. Do not apply the product again until you observe new growth.

poln8r (Robert from Long Beach, MS..)
I've been getting some of Rands' $2 specials the last few years. They grow like mad, even the small ones.

JanetteH (beautiful day in Pilot Mtn., NC)
Thank you, Marilyn

marylois
My deflasked paph babies are just sitting there too...think a spring repot will get them moving.

poln8r (Robert from Long Beach, MS..)
I like to repot mine every year, Lois. They seem to jump right afterwards.

marilyninOttawa
Some Paphs sulk when transplanted and others never look back. I would check out the roots on one of the unhappy seedlings. Maybe the roots are suffering. Try growing the plants in a shadier location and improve the humidity/air movement. Mist frequently. Check the temperature and move the plants to a cooler location unless they are warm-growing types.

marylois
Right - but my spring repot can't start til after about 5 May this year.

barbaratague
1, When repotting, do you wet the bark before potting or use it dry? Which way is better for the roots. (I dampen media before use. I suggest the added humidity around the roots lessens the chance that the dry medium absorbs moisture from the roots until they resume growth. ML)

2, After repotting, how soon should plant be fed?
(I generally begin very weak fertilizer application about a week or two after repotting. Once roots are growing, I fertilize at the regular dilution. ML)

3, When repotting Disa, dry or wet it first?
(I use freshly moistened New Zealand sphagnum moss. ML)

marilyninOttawa
Well folks, I think that it is time to call it a night. Thank you all for your discussion. Looking forward to seeing some of you in Vancouver. Cheers.

Clare in LA
Marilyn, hope to meet you next week.

kbbarrett (Kathy in N Calif)
Thank you for your time again, Marilyn!!

poln8r (Robert from Long Beach, MS..)
Thanks, Marilyn.

AORCHID (art, simpsonville sc)
Thanks, Marilyn, for answers and insight.

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