April

2017

Foundation Date January 1976.

Next Monthly Meeting:

Tuesday 18th April 2017

Commencing at 7.30pm.

Logan Central Community Centre

Cnr Jacaranda Ave & Wembley Road

Logan Central.

Next Committee Meeting:

Tuesday 2nd May 2017

Commencing at 7.30pm.

Logan Central Community Centre

Work Roster for April 2017

Hall Set-up at 6.30pm

Those that can come early.

Supper: Heather Forman and Larry Roberts.

Thelymitra ixioides

Spotted Sun Orchid

Postal Address

PO Box 411 WOODRIDGE 4114

Queensland Australia

Patrons: Logan City Mayor Luke Smith

and Graham Oldham

President Ken Martin Ph 3341 5474

k.marto0011@gmail.com

Vice President Reg Illingworth Ph 3800 3213

Secretary Jan McKenzie Ph 3208 8721

jangmc@optusnet.com.au

Minute Sec. Julie Copley-Bishop Ph 0422 015 991

Ass Secretary Sonya Crosby Ph 0438 198 192

Treasurer Doug Mogg Ph 3806 5316

N’letter Editor Reg Illingworth Ph 3800 3213

lados.editor@bigpond.com

Committee Members

Adrian Bergstrum Ph 3805 8224

abergstrum@hotmail.com

Librarian Olympia Pearce Ph 3800 9231

Myrella Coppus Ph 3341 5691

Phillip McCallum Ph 3427 7774

Kurt Raup Web Master Ph 3388 8771

Alfred Filia Ph 3844 4704

Maree Illingworth Ph 3800 3213

Win Watts Ph 3805 6197

Cultural Award

Plant Name: Dendrobium Tanida Two-Tone 78.1%

Exhibitor: Haase K

Owners Comments:

Housing: Orchid is grown in a covered shade house with 60% shade

on roof, including solar weave and 50% on sides. Four fans run during

daylight hours to circulate hotter air that gathers in the gable roof.

This orchid is a warm grower and requires high light at around 2000

to 3000 foot candle

Feeding: : Orchid is fertilized using Horticultural Solutions HSO22 and HSO12 alternating fortnightly between both 12 months

of the year. Rate is 1 gram per ltre. On alternate fortnight, orchids

are foliar fed using HSO22 and HSO12 at same rate as above but also

adding Amino K and Hysan to the foliar feed.

Watering: In summer, at least daily and sometimes more in ex-cessive heat. Watering or misting is less in winter but would be misted on average every day in mid morning after it has warmed up

a little. However take note of the prevailing weather conditions and

alter the frequency depending on whether it is extremely hot sum-

mer days or cooler than normal conditions. The orchid house is also

misted regularly especially on hot days.

2

Editorial

This month we have the usual format, Page 1, at the March meeting the judges did not nominate a Special Interest Plant of the

month . I have used the photo and description from the Cultural Award to complete this page, Page 2 the upcoming shows, the guest

speaker for April is to be announced. Page 3 has the minutes from the March meeting and the Committee Notes for April. Page 4 has

the benching results for March and Page 5 has the photos of the winning plants, Page 6 has Barry’s Column for the March benching and

info about the sausage sizzle at Bunnings Underwood on Saturday 22nd April. Page 7, has the Saturday Cultural Information Meeting,

also the news about the stocks of bark, Judges for the April meeting and a little bit of life, on page 8, a note about Sphagnum Moss. Page

9 continued from March Newsletter the final part of 3 Parts of an Article by Stephen Batchelor for the AOS Beginners Series about Air

Pollution.

The Mothers Day display at Centro is a goer, setup will be on the Wednesday before Mothers day which is on May 14th and will run till the

Saturday afternoon. These days are yet to be decided as the shops all stay open from 8 or 8.30am till 9.00pm.

Reg

SHOWS TO COME

Queensland O. S. 14/15 April, Botanic Gardens, Mt. Coot-tha.

Bribie Island O. S. 14/15 April, The Orchid House, 156a First Ave,

Bongaree.

Redlands O.S. 22 April, Donald Simpson Centre, 172 Bloomfield St,

Cleveland.

Lockyer Valley O. S. 5/6 May, Gatton Shire Hall.

Aspley O. S. 13 May, Community Hall, Edinburgh Castle Rd.

Wavell Heights.

GUEST SPEAKER FOR THE APRIL MEETING

The Guest Speaker for the April meeting is yet to be confirmed.

Web Address:

www.lados.org.au

Facebook Address:

To link to our Facebook page. Place mouse on Facebook

operate Control key and click on left mouse button.

How to start a fight

A more diplomatic approach or even shutting up would have avoided these fights.

One year, I decided to buy my mother-in-law a cemetery plot as a Christmas gift.

The next year, I didn't buy her a gift. When she asked me why, I replied,

"Well, you still haven't used the gift I bought you last year!"

And that's how the fight started.....

3

MINUTES LOGAN AND DISTRICT ORCHID SOCIETY INC.GENERAL MEETING 21st MARCH, 2017

OPENING: President Ken Martin opened the meeting at 7.40 pm.

WELCOME: to all members and visitors. Welcome to our judges: Don Nitschinsk, Ken Unsworth, Michael Billiau and

Adrian Bergstrum. Associate Judges: Ken Haase and Jan McKenzie. Scribes/Stewards: John Simons, Ryan Hocking, Bev

Pritchard and Phil McCallum.

APOLOGIES: as per register

MINUTES: The minutes of the February 2017 meeting published in the March Newsletter were passed on a motion by

Phil McCallum seconded by Pam Price.

CORRESPONDENCE INWARDS and OUTWARDS: Accepted. Moved Julie Copley-Bishop. Seconded by Myrella

Coppus.

FINANCIAL STATEMENT: Treasurer Doug Mogg moved and Myrella Coppus seconded that a statement showing bal-

ances of: General Account: $10,609.98 Investment Account: $6,406.87 be accepted and that the following accounts be

accepted for payment: B. Mitchell $400.00 print flyers, R. Illingworth $50.00 postage.

NEW MEMBERS: No applications

GENERAL BUSINESS:

President Roster circulated for the April 22nd (Saturday) Bunnings Sausage Sizzle two sessions (7.30–12 and 12 - 4.30).

Four volunteers at each session are required. Ken was pleased to advise members that the last Bunning Sausage Sizzle

raised $607.00 for the Society.

Roster circulated for the Centro Mothers’ Day Display and Sales - Wed. 10th May 4 pm set-up (Centre is open till 9pm)

11th – 13th May. Flowering orchids and many helpers are needed over the three days.

Plant sales tags are available on the front table.

Ken Martin advised members that the Society now has bags of charcoal 10K for $25 a bag, sizes10/20ml. If interested,

please contact Ken for times re pick up.

Ken also called for expressions of interest for the purchase of a Society tee shirt with badge. A batch price for 50 will be

sourced.

Brisbane Orchid Society Show brochures were available on the front table. Ken Haase talked about the upcoming BOS show

(who was giving the potting demonstrations and the vendors). If our Society members bench two plants there they can sell.

LADOS members and orchids are needed at the BOS Show for our table-top display set up on the 31st March.

Show: Next show meeting to be held in May.

Phil McCallum showed the new, quite distinctive Show flyers to the meeting.

Trade table: Adrian Bergstrum reported that there is now a full stock of Seasol, Power Feed and that there is an insecticide

catalogue available to members. A bulk order for pots will be ready soon. Cal Nitrate is no longer stocked. Cork is avail-

able but has to be cut and priced. Thank you Adrian.

Kitchen Duty: for the 18th April meeting: Heather Forman and Larry Roberts.

Many thanks go to Win Watts for organizing the roster for the upcoming meetings.

New Growers’ Group: The topic for the April 1st meeting is to be repotting and potting in Spag.

Guest Speaker: Reg Illingworth shared his extensive knowledge of placing orchids on mounts. Many of the ways were

creative on a practical level and kept his audience’s attention as various examples were handed around the meeting.

Thank you Reg.

JUDGES CHOICE AWARDS: Ken Haase assisted by Phil McCallum announced the winners of the benched plants.

CULTURAL AWARD: Dendrobium Tanida Two - Tone 78.1 Ken Haase

SPECIAL INTEREST AWARD: No award

EXHIBITOR’S AWARD: Unknown

POPULAR VOTE: Open Dendrobium Tanida Two - Tone Ken Haase

Intermediate/Novice Catasetum fimbriatum Ryan Hocking

CLOSURE :- Meeting closed at 9.30pm Thank you to all who helped tonight

Julie Copley-Bishop Minutes Secretary

MARCH COMMITTEE NOTES

At our last committee meeting it was discussed that more helpers will be needed at the Centro Mother’s Day display and

sales from the 10th to the 13th May. Many flowering orchids will be required for the success of the stall. The roster is to be

circulated at the April general meeting where Win Watts is to speak of her positive experience of helping out on the stall last

year. The committee also discussed the sale of flowering plants to members prior to the judging and the opening of our

Show to the general public. The committee advises that the LADOS club badges have been successfully sourced for mem-

bers. The committee also thanks the Society members who came out in bad weather and road conditions to set up our dis-

play at the recent BOS Show where we won a second. Well done.

Julie Copley-Bishop Minutes Secretary

4

1 DENDROBIUMS:

1 Den. Burana Stripe 'Round' Mogg D

2 Den. Tandia Two-Tone Haase K

3 Den. (Dal's Pixie x Dal's Pride 'Algester') x (Dal's Dazzler

'Bette' x Burana Stripe) Haase K

2 CATTLEYAS Over 100mm:

1 Rlc. Glenn Maidment 'Southern Cross' Haase K

2 Rth. CRB's Reward 'Jimar' Zimmerman J & M

3 Rth. CRB's Reward 'Jimar' Zimmerman J & M

3 CATTLEYAS 60-100mm:

1 Rlc. Hawaiian Passion 'Kermie' Cox G

2 C. Dal's Choice Haase K

3 C. Frank's Valentine Zimmerman J & M

4 CATTLEYAS Under 60mm:

1 Rth. Free Spirit 'H & R' Haase K

5 CATTLEYAS Novelty or Cluster:

1 Rby. Everything Nice 'Exquisite' Gill C & M

2 Gct. Starrlyn 'Jimar' Zimmerman J & M

3 C. Little Beau 'Dark Beauty' Cox G

6 PAPHIOPEDILUM:

1 Paph. Golddollar x parishii Tierney M

2 Paph. Ruby Charles Tierney M

7 VANDACEOUS ALLIANCE Flowers up to 40mm:

1 Rhctm. Ladda Gold Mogg D

2 Prra. Bangkok Sunset 'Bright & Showy' Haase K

10 ONCIDIINAE:

1 Onc. Sharry Baby Cox G

2 Brsdm. Aloha 'Elizabeth' Mogg D

3 Gom. Alosuka 'Claire' Haase K

11 MISCELLANEOUS LARGE 50mm and over:

1 Ctsm. Lovena Mogg D

13 AUSTRALIAN NATIVE HYBRID DENDROBIUM:

1 Den. Colonial Maid 'Verity' Berry P

14 AUSTRALIAN NATIVE HYBRID OTHER THAN

DENDRONBIUM:

1 Sarco. Velvet Tierney M

15 AUSTRALIAN NATIVE SPECIES:

1 Den. bigibbum 'Blue' Haase K

16 SPECIES EXOTIC SYMPODIAL:

1 Epi. porpax Haase K

2 B. nodosa var. grandiflora Haase K

3 Milt. spectabilis var. moreliana Cox G

17 SPECIES EXOTIC MONOPODIAL:

1 Phal. violacea Haase K

2 Phal. pulcherrima var. peloric Haase K

3 Phal. cornu-cevi 'Red' Haase K

19 INTERMEDIATE DENDROBIUM ALLIANCE:

1 Den. (Burbank Queen x Chao Praya Gem) * Kehoe A

2 Den Asternova Cascade * Kehoe A

20 INTERMEDIATE ANY OTHER GENUS:

1 Lsz. Lava Burst Kehoe A

21 NOVICE CATTLEYA ALLIANCE:

1 C. Exotic Smile 'Spring Sensation' Hatzirodos J

2 Rlc. Deception Grace * Hatzirodos J

3 Rlc. Deception Kokoda * Hatzirodos J

22 NOVICE DENDROBIUM ALLIANCE:

1 Den. Burbank Pure * Jeffrey K

2 Den. Unknown Hocking R

3 Den. Udom Blue Angel x Masako Taki 'Blue' Hatzirodos J

23 NOVICE ANY OTHER GENUS:

1 Ctsm. fimbriatum Hocking R

2 V. Unknown Hocking R

3 V. Topaz Ulysses x Rhy. coelestis 'Blue' Hatzirodos J

Cultural Award

Dendrobium Tanida Two - Tone 78.1% Ken Haase

Special Interest Plant of the Month

Not Given

Popular Vote—Open

Dendrobium Tanida Two - Tone Ken Haase

Popular Vote—Novice & Intermediate

Catasetum fimbriatum Ryan Hocking

JUDGES CHOICE RESULTS FOR MARCH, 2017

Tabling Statistics are not available with the new procedure

CORRECTION TO PLANT TAGS

Would all Members who will bench orchids at any future

meetings, please change their plant tags as necessary, so that

we do not have to do these alterations continuously.

Changes are marked in Red and with an *

5

1. Dendrobium

1st. Den. Burana Stripe

'Round' Mogg D

3. Cattleyas – 60mm to 100mm

1st. Rlc. Hawaiian Passion

'Kermie' Cox G

16. Species – Exotic

Sympodial

1st. Epi. porpax

Haase K

6. Paphiopedilum

1st. Paph. Golddollar x

Parishii Tierney M

2. Cattleyas – Over 100mm

1st. Rlc. Glenn Maidment

'Southern Cross' Haase K

17. Species – Exotic

Monopodial

1st. Phal. violacea

Haase K

5. Cattleyas – Novelty or Cluster

1st.Rby. Everything Nice

'Exquisite' Gill C & M

10. Oncidiinae

1st. Onc. Sharry Baby

Cox G

21. Novice Cattleya Alliance

1st. C. Exotic Smile 'Spring Sensation'

Hatzirodos J

23. Novice Any Other Genus:

1st. Ctsm. fimbriatum

Hocking R

14. Australian Native Hybrid

Other Than Dendrobium

1st. Sarco. Velvet Tierney M

7. Vandaceous Alliance Flowers

up to 40mm:

1st. Rhctm. Ladda Gold Mogg D

11. Miscellaneous Large

50mm and over:

1st. Ctsm. Lovena Mogg D

19. Intermediate Dendrobium Alliance

1st. Den. (Burbank Queen x Chao Praya Gem)

Kehoe A

4. Cattleyas Under 60mm:

1st. Rth. Free Spirit 'H & R'

Haase K

13. Australian Native

Hybrid Dendrobium:

1st. Den. Colonial Maid 'Verity'

Berry P

15. Australian Native

Species:

1st. Den. bigibbum 'Blue'

Haase K

20. Intermediate Any Other Genus:

1st. Lsz. Lava Burst

Kehoe A

22. Novice Dendrobium Alliance:

1st. Den. Burbank Pure

Jeffrey K

6

Some Plant Tabled at the March Meeting

A Dendrobium Burana Stripe ‘Round’ was tabled and if

not this plant another division of the same clone has

been previously entered and mentioned, a top class

exhibit that was first in it’s section, so it’s photo will

appear in the newsletter so no further comment ought to

be necessary.

Another entry previously seen, and possibly the same

plant was Den. Lasida Two Tone with some fourteen

spikes, and although presenting themselves closely

together were not overlapping but their closeness

deterred my trying for a more accurate count and the

same naturally goes for the flower numbers. The

blooms were small (on this “compactum” style plant)

when compared to it’s larger growing relatives and of

not at all bad shape. Blooms were pale mauve with

white tips to some segments with purple to base of lips.

As the spikes were not long the floral display covered

most of the plant’s top, hiding not a small percentage of

the foliage.

Cattleya Novelty or Cluster featured the former

Brassolaeliocattleya, now Rhyncobrassoleya (abbv.

Rby.) Everything Nice ‘Exquisita’ carrying five blooms

with lime to apple-green tepals with mauve, open, but

not fully flared lips that were darker to their centres, this

hue becoming lines over a yellow base tone with the

exterior of these being white. The blooms of this

Brassovola hybrid were larger than many encountered

among primary hybrids of this genus. The blooms were

a trifle crowed, but its forte, the colour combination,

more than compensated. I also liked the Brassavola

style bulbs and foliage.

Another Cattleya Alliance entity that is no longer a Blc.

but a Rhyncattleanthe is Rth. C.R.B.’s Reward ‘Jimar’

and saw two plants displayed of one and three blooms

respectively that were of reasonable form with tepals of

pale mauve and petals of a darker hue and having white

stripes along their centre lines from base out to over

halfway, from there out to tips was a dark shade,

comparable to that of the goffered lips, which was

purple tone. White tips of lips with yellow stripe

towards throat. A narrow band of mauve from the top

edge of one side-lobe across the mid-lobe region

connected with same point opposite bisecting the frontal

zone from the paler base. Markings such as those to the

lips and petals of these blooms give them an

individuality beyond the mundane.

A name, unknown Vanda was tabled in Novice Any

Other Genus, and displayed it’s seven blooms on an

upright spike clear of, if not all above the foliage. The

tepals were tessellated red all over, more heavily to the

ventrals, with this colour also appearing in spots to

petals and dorsals, all this over a reddish-orange base

colour, while lips had red-purple tips backed by yellow

bases. Shape was what I would consider to be of above

average form in relation to my appreciation of show-

bench type Vandas, which are those that show a distinct

outline of the tepaline segments, and not the featureless,

circular, saucer-shape of many latter-day hybrids.

Another Novice A.D.G. was Catasetum fimbriatum, this

carried twelve blooms well spaced on it’s pendulous

spike. These were of a green base tone with a

yellowish hue to their fimbriated lips, these with some

fine red spotting to their reverse which showed through

to the front. Petals were heavily spotted a dark reddish

colour with slightly paler toned smaller spots to

ventrals.

Miscellaneous Large had tabled a Catsm. Lovena which

grex is 50% Ctsm. fimbriatum with this species showing

its influence on flower form. A very nice hybrid, and I

have a notion, going by the name, that this or another of

the grex was shown at a meeting last year.

In Oncidiinae was a Miltoniopsis, due to whose name,

as with the previous plant, came to mind as an entity

encountered in the not to far distant past. The blooms

were familiar as was something (but what?) about the

grex name, labelled here as Nakamoto ‘Tanto’, hinted

that I’d checked it out once before; that I had was

revealed due to another check, when again the nearest

title to this, Mps. Lillian Nakamoto was encountered.

This latter grex was registered under it’s then, (now

former), accepted genus of Miltonia in 1994.

Whether my previous check was for our newsletter or

just a personal snoop to ascertain its ancestry after

seeing a clone by this name elsewhere, unfortunately I

can’t recall. The plant’s five white blooms had dark,

indeed black, marks to their labellum crests and these

had a sharply pointed serration like finish to their lower

edges.

A Den. Fraser’s Canary Twister had two spikes, the

largest carrying a couple of dozen blooms and several

buds, these being of an apple green colouration,

featuring a single full twist to petals while dorsals and

sepals were only half so. These few remarks seem

insufficient to describe a very good example of a true

intermediate type dendrobium. Blooms were of good

shape, not large but plentiful; this smaller size and

floriferousness could be credited to it being half Den.

canaliculatum.

Great news, we have another Sausage Sizzles to do at Bunnings Underwood. Ken will be sending around the roster for volunteers at the

next meeting. We require 4 persons 2 shifts a day. Give it some thought as this income eliminates us from going around cap in hand seek-

ing donations to run the Show.

The date is Saturday 22nd April, being on a Saturday the return to us should be reasonable.

7

POTTING SUPPLIES ORCHIATA Bark is available FROM Ken Martin, Phone 3341 5474. 9 Dianna Street UNDERWOOD.

It is available in 4 sizes, Small 6-9mm, Medium 9-12mm, Large 12-18mm and Extra Large 18-25mm.

The price to LADOS members is $25.00 per 40L bag

The Society has sourced Charcoal in 10K bags for $25 a bag, sizes10/20ml from Ken.

When buying a quantity of any product, Adrian has requested that you ring him so a suitable supply of stock can be brought

to the hall as it makes it possible for other members to purchase product.

You can call him, Adrian Bergstrum 3805 8224 or Email abergstrum@hotmail.com. It is probably best to call before

lunch as Adrian works an afternoon shift at WW bulk store.

The Logan and District Orchid Society Inc.

Saturday Cultural Information Meeting

nvitation to all Logan & District Orchid Society Inc. members to attend the meeting of the The Logan and District Orchid

Society Saturday Cultural Information Meeting, at 51 Lionheart Street, Forestdale 4118

The meeting will be at 9.30 am on Saturday the 6th of May 2017 The topic for the May meeting is Nomenclature

Please bring along any problem plants or a plant in need of a repot and if time permits we can discuss these

problems and repotting methods.

As with previous meetings it would be appreciated if you would contribute $1.00 towards the cost of photocopying.

Our phone number is: 3800 3213

Our address is: 51 Lionheart Street

Forestdale 4118

Maree and Reg are looking forward to seeing you on the day.

Judges for the April Meeting There will be four Judges and any associate Judges that request to observe the procedure.

If there are sufficient plants on the benches the Judges will operate in 2 teams.

The allocated Judges are Don Nitschinsk, Michael Billiau, Jeanne Rutherford and Maree Illingworth.

The scheduled associates. are Gordon Grant and Jan Teufel.

Members wishing to help with the stewarding please see Maree as she will be selecting them on the night.

8

Sphagnum moss comes from bogs and is harvested, compressed and imported for use in the floral industry. There are many

graded levels of sphagnum moss. The quality of sphagnum moss is relative to the length of the strands, how fluffy each

strand is, and how much debris is packaged in with the moss. Lower quality moss obviously costs less. The sphagnum moss

that is used by the floral industry to line hanging baskets and package seedling plants for transport is typically of a much

lower grade than we would choose for use as a moss to grow orchids in.

In the growing of orchids we are looking for top quality sphagnum moss with long, fluffy, open strands and good capillary

action for moisture. In Taiwan, the largest exporting country of Phalaenopsis orchids, virtually all Phalaenopsis are grown in

Sphagnum moss. In cooler climates and in cultivation in the home, sphagnum moss can present some challenges with over

watering. The good news is, sphagnum moss as an orchid medium is highly adaptable. Packed tightly in a pot it will retain a

lot of moisture. Packed lightly in a pot it will dry out rapidly. But here is where the quality of the moss really comes in to

play. Standard floral-quality sphagnum moss, available from nurseries and box stores and even sometimes advertised as

'moss for orchids' is often not suitable for growing orchids. Orchids grown in this lesser grade of sphagnum moss will not

thrive as they could in a higher grade of moss as this moss compacts and quickly becomes sodden in all but the most arid

environments.

For orchids we recommend AAA New Zealand Sphagnum Moss or 5 Star Chilean Sphagnum Moss only. The quality of the

two is fairly comparable though AAA New Zealand Sphagnum Moss is fluffier. These two products will be labeled as such,

the lesser grades of sphagnum will often be labeled as 'moss for orchids', 'organic moss' or simply 'sphagnum moss'.

It is important to clarify the difference between sphagnum moss and sphagnum peat moss, also called just 'peat moss'. Sphag-

num peat moss is not the same thing as sphagnum moss. In a sphagnum bog the sphagnum moss is the living moss that floats

on the top of the bog. Sphagnum peat moss is the dead moss that falls to the bottom of the bog. Upon harvesting, the top

layer of live sphagnum moss is taken first and then the bottom layer of peat moss is harvested. Peat moss is then processed

into a soil amendment that is also a media used with orchids but it is markedly different in appearance and texture. Much of

the sphagnum moss and sphagnum peat moss we see here in nurseries and big box stores comes from Canada.

Sphagnum Moss For Orchids

9

HUMIDITY Porous gravel generates reasonable amounts of humidity in this way by imbibing water, thereby exposing it to more air. Orchids themselves, especially in large numbers and in freshly watered media, do at least partially con-tribute to the overall humidity in a similar way. Some humidifiers generate humidity by "atomizing" water into smaller amounts, creating a fine mist far more subject to air and far more likely to become a part of it. Other types of humidifiers expose small droplets of water to large volumes of air by blowing air through a fibrous pad mois-tened in traveling through a tray of water, conveyor-belt fashion.

Shriveling of a normally smooth and succulent leaf of a Cattleya hybrid re-sulted when a Cattleya hybrid was sub-jected to low humidity and high light. Photo: Greg Allikas

Evaporative coolers make use of the fact that water needs and absorbs significant amounts of heat and energy to go from the liquid to the gaseous state, consequently cooling the air or surface involved. Growers can make use of this cooling ability of evaporating water by "syringing", or misting, their orchids. In the process of evaporating, water will momentarily cool the leaves and raise the humidity. But unless done under conditions which will lead to rapid evaporation (high light, warm temperatures, some air movement), and done frequently, the rather fleet-ing beneficial effects are perhaps not worth the greater risk of spreading disease, and the nuisance of mineral resi-dues accumulating on the leaves. Outdoor growers may possibly find misting worthwhile in terms of retarding heat build-up and its resulting sunburn during hot, still, sunny weather. But growers indoors, especially under lights where leaf scorch is not an issue, could better employ their time and efforts by taking advantage of other more effectual devices for generating additional humidity.

Maintaining humidity indoors can be greatly simplified by using a good humidifier operated on a humidistat. Nevertheless, all growers should be aware of things which tend to deplete the air of humidity. Heated or air-conditioned air is low in humidity and can quickly dry the air of a growing area. Humidifiers work overtime dur-ing cold weather when the heat is on frequently. The cold surface of window glass in the winter time will draw water out of the air by the reverse of evaporation, condensation. Double glazing (with polyethylene, for example) will reduce this occurrence by moderating the surface temperature. And, as mentioned previously, humidity levels lower spontaneously as temperatures rise, unless additional moisture is added to the air. Conversely, relative hu-midity rises as the temperature drops, as it typically does during the night time hours. So most efforts towards increasing humidity need be taken during warmer and bright daylight hours, especially indoors when the heat or air conditioning is on.

Hobbyists should strive for the gentle movement of clean, moist air around their orchids. Such a practice helps eliminate, or at least moderate, any extremes which may develop in the growing conditions. Particularly in the case of high light and accompanying warm temperatures, humid, moving air can lower leaf temperatures and re-duce transpiration and water stress. Light, temperature, air movement and humidity ultimately determine the water and nutrient needs of orchids, and there fore watering and fertilizing practices.

Low humidity conditions are especially trying for mounted

orchids, such as the Cattleya hybrid pictured here. Photo: Greg

Allikas

Continued from March Newsletter 2017 The final Part of 3 Parts of an Article by Stephen Batchelor for the AOS Beginners Series about Air Pollution