Keeping The Summer Greenhouse Cool

Summer has finally arrived on the West Coast. The cucumbers in the greenhouse are behind because of the cool wet weather. Now my goal will be to control the hot greenhouse environment.  Fluctuating temperature is often the major cause of plant and crop damage.

Ventilation and air circulation is a priority. Greenhouse vents and louvres will be wide open and circulating fans are set at high speed.  An exhaust fan system in one of my greenhouses works very well to control the greenhouse temperature.  This greenhouse is in a sunny location and the cacti and orchids are there for the summer months. With the prediction of a hot July, I will have to consider attaching a shade cloth to the outside of my glass greenhouse.  Shade cloth fasted to the outside of the greenhouse prevents the heat from building up inside. For further information regarding shade cloth and exhaust fan ventilation packages visit the B.C. Greenhouse Builders website

Increasing humidity will cool the atmosphere and bring down the temperature in the summer greenhouses.  To keep moisture and humidity in the air I always have some watering cans filled in the summer season.  Concrete floors and benches will also take moisture out of the air.  I hose down the floor and benches on hot days. This action is called “damping down” and you can feel the humidity rise.

Plants will require more frequent watering sometimes twice a day depending on the weather and the plants. Greenhouse tomatoes and cucumbers will suffer if they are not watered daily during the summer months.  My cucumbers are in a self-watering grow box but the tomatoes I watch closely. On a dull day, they may get a cup of water and sunny days may receive half a gallon of water twice a day.  I start feeding tomatoes and cucumbers after flowering and the fruits are starting to form. A liquid tomato fertilizer high in phosphate and potash will encourage fruit formation.

Just a quick note:  We have enjoyed another fresh salad.  That was the third crop from the leaf lettuce plants.  So successful I will seed another container of leaf lettuce for fresh salad crops in late summer early fall.






The Home Attached Glass Enclosure A Tropical Paradise


Every morning I open the sliding doors of the family room and walk into my glass patio enclosure.  It is hard to describe the uplifting feeling one gets having breakfast in this bright warm glass room surrounded by a collection of tropical plants.



A Palm tree is a pleasant reminder of a trip to Tunisia.  I brought home some palm tree seeds and was very surprised that the seed started to grow.  Over the years, I have pruned some of the branches because this particular palm tree will grow twenty feet tall.




One birthday I received a Croton plant known for its exotic colored leaves.   My small croton plant thrived so after a transplant to a bigger pot it has grown to become five-foot tree.  Recently I noticed nestled away in the top leaves was a long stem with small white flowers. The croton  will continue to bloom for several weeks. Croton plants thrive in a warm location with no drafts and lots of light.

In the more shaded area is a Ficus Benjamina tree.  The ficus is a temperamental plant that does not want to be disturbed.  If moved all the leaves will drop off.  This plant has not died and new leaves will develop.  Changing seasons will also cause the plant some stress and leaves will drop off.  This is the best time to give the ficus a light pruning.

B.C. Greenhouse Builders designed my curved glass home addition to cover an outdoor patio. Located on the east side of the house we enjoy the morning sun.  For ventilation, the sliding screened windows and exhaust fan keep the room very comfortable.  Under the brick floor is a hot water heating system and during the cooler months, your feet are always warm. I love the wide windowsills to accommodate the various sized pots and containers of orchids, african violets and kalanchoe.  Our glass home addition has become the most lived-in room of the house.

If you are considering closing in a patio area, has lots of pictures of home attached glass enclosures.




Greenhouse Vegetables Plants Ready For Their Growing Season

Finally the exciting time has come to enjoy the fresh salad made from my greenhouse leaf lettuce plants. The lettuce seeds started in February became seedlings and planted into their permanent containers in March.  In early May I took the bigger leaves off the stem and made a delicious salad. Everyone said how soft, tender and tasty the salad was.Leaving the smaller leaves on and only taking the larger leaves off will provide a period of continuous growth on the leaf lettuce plants. These tender lettuce leaves are great on sandwiches.

Cucumbers plants are ready for the summer season in the greenhouse.  I have always had great success growing the cucumbers in Maxikap, a self-watering plant system.  The Styrofoam box is filled with water and a capful of 4-3-7 liquid micro fertilizer. The 40 liter soil grow bag is ideal for two cucumbers plants.  You can go on summer holidays since this self-watering system meets the plants watering requirements for approximately two weeks. These self-watering plant systems are available through Garden Retreat online store at

My hanging basket tomato plants are doing well.  I have never grown this variety maskotka hanging basket tomatoes and it will be interesting to watch them develop. I had expected the plants to be shorter and fuller but they seem to be growing upright.


Love to show off the greenhouse potatoes.  I did tie some rope around them because they were so tall and starting fall over.  The plant growth looks healthy and now waiting for the flowers to appear.


Cacti: A Lifetime Plant Collection

Cacti are greenhouse plants that last forever. I inherited my mother’s cacti collection over twenty years ago and never lost one plant. They are the most adaptable plants for the greenhouse summer and winter temperatures and will continue to produce flowers. Their natural desert habitat is dry and not very fertile soil, fluctuating night and day temperatures and seasonal irregular rainfall.

The cacti are great as companion plants in my greenhouse. No watering is required from October to March, but a light misting may be necessary if the cacti show signs of shriveling.  During the spring greenhouse season the day temperatures increase and then it is time to start giving the cacti a little water. They prefer bottom watering so my cacti pots have water trays. Once the flower buds start to form then I water at least once a week.

Spring is the right time to sow cacti seeds and they will be ready for transplanting in the fall. Cacti seeds are very small so I mix them with sand and sprinkle them in a shallow container of seedling soil mix. There is a long germination period which can be anywhere from three to ten weeks.  Bottom heat from a soil cable really does improve the success rate for germinating cactus seeds.  To prevent the soil from drying out during these weeks, apply a light misting of water.

Mature cacti multiply with “offsets” at the base of the plant.  Removing the prickly offsets can cause injury to the fingers and I use garden gloves and tweezers.  The offsets are dried overnight before transplanting. For transplanting I purchase a coarse cacti soil mix that consists of crushed gravel, sand and bricks. Cacti prefer small pots and like to be root bound. Later they will be repotted into larger pots or a more permanent location. Small potted cacti plants make great gifts for family and friends who say they can never grow a plant. A few weeks later, they tell me “my cactus is on the kitchen windowsill and still surviving.” I just have to remind them that it is good to neglect this cactus to force it to bloom.

In my greenhouse, the permanent location for the cacti is on glass shelving which is attached to the greenhouse sidebars.  I make sure there is always adequate greenhouse ventilation and air movement because overheating can cause cacti damage.


One of my favorites is the hanging basket with an orchid cactus.  This cactus has long thick stems and the flower petals form along the stem. It is in full bloom and what an incredible display of vibrant red orchid like flowers.

Controlling Greenhouse Pests and Diseases

Warmer greenhouse temperatures create the ideal environment for pests and bugs to co-inhabit with the plants.Daily checking the plants will determine what preventative measures to take to control greenhouse pests and diseases.

White fly is a well-known greenhouse pest and difficult to get rid of.  I use yellow non-toxic horticulture strips and hang them in different locations in the greenhouse. Yesterday I went on a field trip with my grandson to a large greenhouse complex and was surprised to see the yellow sticky strips.  The children were told yellow is the only color that attracts flying insects in the greenhouse. She was correct because I have tried and tested many strips and found the yellow ones provided the best results.

As soon as I see a white fly, aphids or spider mites on a plant it is sprayed with an organic product called Safer insecticidal soap. You can learn more about this insecticide soap on

Spider mites love the gardenia in my solarium.  Normally I take the plant outside and give it a good wash with safer soap.  I had heard that leaf shine controls spider mite so this spring I applied it to the gardenia.  Not only does it seem to be effective in controlling the spider mites but also the plant leaves looked shiny and clean.

Here are some preventative measures I use to keep my greenhouse pest and disease fee.

  1. Once a year the inside and outside of the greenhouse gets a good cleaning. This task is usually done when the least amount of plants are in the greenhouse.  A good cleaning solution for glass greenhouses is hot water and a disinfectant such as lysol or pinesol.  Polycarbonate greenhouse has a UV coating on the panels.  A recommended cleaning solution for a polycarbonate greenhouse is to use a mild detergent and then give the panels a good rinse.
  2. Using sterilized soil and careful watering is another preventative measure against plant diseases.
  3. Make sure the greenhouse has constant air movement from a circulating fan and adequate ventilation.


Preparing Greenhouse Plants For The Garden

Yes, my greenhouse has become too small.There are baskets, pots and seed trays everywhere. I love the feeling of spring fever in the greenhouse. All the daily greenhouse activities and now preparing the bedding plants and baskets to go outside in a few weeks.

In the greenhouse, plants and baskets no longer require the night heating. I slide up the screen on the door and keep the louvers open day and night. This is a time the seedlings may need some shade protection. Shade cloth is fastened to the outside of the glass greenhouse.  I watch the maximum-minimum thermometer closely for temperature fluctuations. On a sunny day the door is left open. A period of acclimatizing or “hardening off” the plants needs to take place. Next week I move the plants and baskets outside to a protected area. If a cold night is in the weather forecast, I can cover them with some plastic.  Cold frames are ideal during this “hardening off” period. This process of acclimatizing the plants prevents them from going into shock and the leaves turning blue when planted into the garden.

When planting the bedding plants, I pinch back the flowers on the bedding plants. This sounds drastic but it will encourage new growth and flowers. During the summer months the flowers are  “deadheaded” to insure continuous growth and blooms.