Dora’s Greenhouse


Dora Glover is one of the founding members of the CVIOS.  Dora has been President of the Society and helped out in every facet of our activities.  She has participated in many shows and had many award winning plants.  Her contributions have been recognized by the Society by granting her a Life Membership (there is a small limit on the number of Life Memberships granted).

Dora started growing orchids in 1972 and has a wealth of experience to share.  She was a wonderful source of information when I was planning my greenhouse, so feel free to approach Dora with any orchid questions.

Her favourite orchids are Cattleyas, particularly white with red lips.

Dora suggests the most important point for a beginner to consider when buying an orchid is "where is the plant going to be grown".  Depending on whether you have a closet or basement with lights or an east window or south window or greenhouse will determine what environment you can provide the plant.

Planning a Greenhouse

Like many members, Dora's collection outgrew her old wood greenhouse. She has been impressed with the advantages of the new aluminum framed replacement.  The aluminum frame is accommodating for hanging lights and supports for hanging baskets.  

You can see (in the above picture) the advantage of enough height to hang baskets from the roof.  (I am sure anyone with a lower roof line has had the repeated awakening of head bashing encounters with heavy hanging baskets.  Why is it we never learn and hit them over and over?)

Ventilation and air movement is important to pest control.  Dora has automatic roof vents, five fans and also side vents.   

Dora has a gravel floor so water can get away.  It is easy upkeep, as gravel will not grow a slippery layer of algae which needs to be controlled on a cement floor.

I was quite impressed by Dora's hanging wall.  One never has enough space in a greenhouse.  So here is a way to place a number of pots in a small footprint.

Fertilizer and Water

Dora suggests having hot water available in the greenhouse as using cold water can cause cell collapse on leaves (particularly the Phals) leading to pits and a possible entry site for disease.

She waters once per week fertilizing every time with whatever is on hand (15-30-15; 30-10-10 or 20-20-20).  The fertilizer is mixed in a 5 gallon pail and a Syphonex is used.  Epson Salts are added now and then (magnesium sulfate).  

A couple of tablespoons of Physan 20 is added once per month.  (Physan 20 is not available in Canada but "hth Algicide10" is available at any Canadian Tire store (swimming pool department).  It has the exact same chemical as comprises half of the Physan and is half the strength of Physan 20.  Note the Canadian Tire house brand algicide has a strength of only 5 (%)). Click here for a page on Physan use.

Temperature / Humidity / Lights

warming tray.JPG

The night temperature is held up to 65 F and an exhaust fan starts at 90 F.

Dora installed a misting system (components available at Home Depot) and set up a timer so the mister comes on three times a day for 2 to 3 minutes.  It is set for 9; 11 and 1 so the plants are sure to dry out before the night's cooler temperatures.  With the fans going, the mist is well circulated.

 The above picture shows a warming tray Dora had made from plexiglass.  It is 3' by 4' and has a heating cable in sand under the plants.  The plexiglass holds in water to keep the sand moist as moist sand transmits the heat better than dry sand.  The warming tray is a good idea for starting seedlings as it is the roots which need the higher temperature more than the leaves.


Dora uses a bottom layer of styrofoam peanuts for drainage and then about half and half; lava rock (or clay pellets) and bark.



She suggests repotting every two years and to do so when there is new growth.  If you repot when the plant is dormant it may have trouble recovering from the disturbance, but an actively growing plant will grow into its new environment.

ALWAYS use sterile tools.

Here we have a plant that is trying to grow out of its pot.  Note the pitted leaf which Dora attributes to having used a cement board as the back of her hanging wall.  Chemicals must have dissolved from the cement board and harmed the leaf.  The new growth is fine once the cement board was removed.


Note how airy the old mixture is.  Orchids need water but the roots also need air and good drainage.  There is no soggy mess here.


The plant is placed over the styrofoam peanuts and you can see how loose the new mix is.

Finished.  Repotting should not be intimidating.  Note the simple homemade hanger to hang on the hanging wall.

Here is a Cat that seems to be happy in just lava rock.

Thanks Dora for your comments.