Starting Begonias In The Greenhouse

I know spring is just around the corner when I prepare my begonias tubers to spend a few months in the greenhouse. They have been stored in the garage, a frost-free environment. Begonia tubers are available this time year at local garden centers. Begonias are shade-loving plants and will provide spectacular displays of continuous flowering from June to early fall.

Selecting a good tuber, you will note the center will show signs of life in the form of pink tips.  The container or pot used is according to the size of the tuber.  Fill this pot three quarters full with moist peat and perlite mix. Firmly place the tubers into the pots with the new growth up and then cover with ½” of peat mix.  Using the propagation bed, the bottom heat will encourage root formation and stems will sprout. It is important to keep the growing medium moist but not wet. A few hours of supplementary light with grow lights will give the begonias a head start.

Once there are a couple of inches of leaf growth, gently lift them and re-pot them into their final container or basket.  Begonias prefer a soil mix that drains quickly.  The baskets or pots will thrive in a bright location in the greenhouse. As the spring season becomes sunnier, these plants will require a light but shadier area of the greenhouse.

It is interesting to note that begonia tubers will substantially increase in size during the summer months. My begonia tubers have become quite large over the years and I have divided them. When I take them out of storage, they are dry and so it is easy to cut or divide the tuber. Sometimes a piece will break off, which is potted on as a new tuber.  Chances of success are better if this piece has a growing tip.


  1. Clean all pots, containers, and baskets with hot water and a disinfectant like Lysol or a few drops of bleach.
  2. Mildew on begonia leaves is caused by lack of air circulation. When this occurs, the affected leaves must be removed and the plant relocated in the greenhouse.

Greenhouse Ventilation Not Just Seasonal

Today is a bright and sunny day and the greenhouse temperature quickly rose to 24?C (75?F).  Ventilation in the greenhouse is not just seasonal. This is February and yes today the greenhouse requires ventilation to maintain an even optimum environment for the plants.

Most greenhouses have roof vents equipped with automatic openers and they will start to open slowly.  Ventilation is required so there is no heat buildup especially at greenhouse bench level. Hot air will build up, rise and escape, and the open roof vent will be a source of cool air intake. A circulating fan will equalize the greenhouse temperatures with constant air movement.

My greenhouse has side louvers and I have to be careful when I open them.  The louvers are at bench level and a sudden blast of cool air will cause plant damage.   The top louvers will be open slightly for several hours and will close them in mid-afternoon to conserve the day’s heat.

Greenhouses that do not have automatic vent openers or louvers will depend on an exhaust fan system for ventilation.   Exhaust fan thermostats are usually set at a higher temperature 30?C (86?F). An intake shutter working together with the exhaust fan will exchange the air in a few minutes. The greenhouse will cool and the fan shuts off.

Now some plant news in the solarium.   I have one very interesting orchid blooming.  This orchid produces flowers one at a time on the same stem and will continue flowering for quite a while.  I do get a chuckle from people’s comments on the orchid.  They either love it or do not like it all.


The Cool Winter Greenhouse Is Ideal For Growing Potatoes

Growing potatoes in the greenhouse is fun and they do not require much care. Early potatoes started in January or February will have a late spring crop. Another planting done in August will have a harvest for Christmas Day.

Seed potatoes are available through garden centers and nurseries. Seed potatoes that have visible sprouts are the best for planting.

For greenhouse gardening I have always prepared my own soil mix with a sterilized potting soil, perlite, and peat.  In the last few years, I have also been working with Sunshine professional horticultural mix.  It has proven successful for starting seedlings and transplanting annuals.  Now is the time to experiment using this horticultural mix of peat and perlite for the potatoes.  According to the label the uses for this mix is pot, bedding and vegetable crops.

A layer of 6”-8”of soil or mix is placed into a well draining pot or container. Using a 16” pot the three seed potatoes are spaced so they have room to develop.  Add a few more inches of soil or mix and situate the pot in a sunny greenhouse location. The pot is only half-full for a reason. Once growth starts to appear and the plant is 6” tall then it is necessary to “hill”. This means adding another small layer of soil or mix.  Some leaves will be covered but keep 2/3 of the plant growth exposed. As the plants grow, continue to “hill” until the pot or container is filled to the top.

When the potato plant has finished flowering the potatoes are ready to harvest.  It is exciting to dig up the amount of potatoes needed for a meal. I love the taste of new potatoes and look forward to a few meals from these plants. Some people wait until the plant dies off, harvest all at once, and store the potatoes.


  1. Potatoes are kept moist but not wet.
  2. To prevent pests and diseases in the greenhouse environment use a sterilized soil or growing mix.  Peat and perlite are a sterilized growing mix.

The Importance of Pruning and “Pinching Back” Greenhouse and Solarium Plants

Sunny days in February are wonderful and the greenhouse temperature will rise providing the plants with additional warmth.These warm periods of sunshine and brighter light will activate plant growth.The plants will start to grow accordingly and reach for the light.  Plant stems will become leggy, longer spaces between plant nodes where new leaves are developing.

“Pinching back” is a practice that is difficult, but will keep the plants compact and encourage new growth.  I “pinched back” a two-year old stock fuchsia plant, just above the node on the stem.

It now stops that stem from growing at this point. In the case when “pinching back” is not done, the fuchsia will naturally develop long stems and the middle of the plant would be bare of leaves. This practice continues right through the spring season.   Then the plant will be shaped as to how I want it to develop in the hanging basket.

I have enjoyed a gardenia plant in the solarium for many years.  Pruning of the gardenia took place in January.  The gardenia looked dormant and the leaves were small. Notice the pruned cut is just above the node. The leaves have become noticeably larger and a flower is starting to appear.  This is exciting and waiting for more flower buds that will bloom and leave a sweet fragrant scent in the air.

The hibiscus plant spent the summer on the outside patio. For some reason the hibiscus had minimal summer flowering. I suspected that it would be the last year for this elderly plant.  Hibiscus plants require a night temperature of 10?C (50?F) or they will not survive.  In the solarium, the conditions were just right and the hibiscus continued blooming right into January.  After a good pruning, it proved me wrong, new healthy leaves have appeared and the plant looks great.  I look forward to having my hibiscus for another year.



  1. Greenhouse plants will grow towards the light.  Turning them will lead to the upright development of the plant.
  2. It is natural for older leaves to die off when new leaves appear and very important to remove dead or discolored leaves immediately.




Winter Watering Requirements For The Greenhouse


How much water will greenhouse plants require during the winter season is a question with no definite answer.  The amount of heat and light will affect the plants watering requirements. In the warmer greenhouses, light conditions may also vary from shade, indirect light to full light.  Therefore, checking each plant will determine which one will require a more frequent watering.

Plants, which located in the cool greenhouse to winter over, will be in their dormant period. Rooted cuttings are slowly developing their root system.  Therefore, plants and cuttings are watered sparingly.  Yes, so sparingly it may only be a few drops when necessary. First, I lift the pots and feel if they are heavy or light.  If they are lightweight, I check the soil to see how dry the plant really is.  Quite often, there still is moisture half way down the pot.  If there is no moisture, then the plant receives a few drops of water.   Depending on how much winter sunshine watering may be required once a week.

Last week I noticed some variegated geraniums developed a mold.   Mold becomes evident when the soil is too moist. The problem was my garden geraniums were still blooming late into the fall season. I delayed cutting them back and bringing them into the greenhouse.  My conclusion is that these stock plant’s root systems were wet from the rain and the plants should have dried overnight before potting on.  A notation was made in my greenhouse journal.

Greenhouse watering is easy using a coiled hose that can lengthen to 25 feet.  Attached is a long-handled sprayer or watering wand. Automatic watering systems are available but they do require seasonal adjustments to the timer to prevent over watering.

Cacti and other succulents are companion plants in my cool greenhouse. Whenever it rains in the desert, cacti start to bloom.  In the greenhouse, no watering is required from October to March. During this time if a cactus show signs of shriveling a light misting of water is applied.  In the spring, cacti have a growing spurt.  At that time, a little watering will encourage the flower buds to form.


  1. It is better to underwater plants than over water them. Plants that are under watered usually come back to form with the next watering.  Over watered plants can easily develop root rot and will not survive.
  2. Check each individual plant for their water supply, since some will absorb quickly and others retain moisture.

Watering requirements will increase in March when the daylight hours are longer.


Planning For A New Greenhouse Growing Season

Welcome to the Beginner’s Greenhouse Gardening Guide Blog. I am looking forward to sharing my greenhouse gardening experiences with you.


January is the month for fresh starts and new beginnings. This is also the time to plan for a new greenhouse gardening season.  Browsing through seed catalogs is always interesting with so many more new varieties of annual bedding plants spring seed propagation.

Greenhouse vegetables like cucumber and tomatoes are specialty seeds just for the greenhouse environment.  I recommend visiting and check their greenhouse varieties.  Long English cucumbers are always a favorite, but the shorter variety called Dishon are becoming quite popular.   The greenhouse tomato selection includes cherry and beefsteak varieties.  Another seed company that carries the greenhouse cucumbers seeds is   This company has organically grown seeds for tomatoes and cucumbers.

Selecting seeds for the garden, containers and baskets does require some research as to which plants do well together.  Keeping a greenhouse journal makes it so easy to check back and see which seedlings and plants were successful in the greenhouse last year.

My greenhouse heat is set for a night temperature of 5?-7?C (40?-45?F).  Right now it is filled with cuttings and wintering over plants.




They are in their dormant stage but already new growth is appearing on the pruned back stock or parent plants. I stagger the planting of hyacinth bulbs, so during the winter months there is color and fragrance in the greenhouse. The Christmas cactus is just finishing its flowering.

Enjoy shopping the seed catalogs

Greta Heinen, Author

In Your Greenhouse A Beginner’s Guide

(This title is being revised)