Tomatoes: Growing Greenhouse Tomatoes

Using your greenhouse to grow tomatoes is both challenging and rewarding.  Imagine going out to the greenhouse when the wind is cold and blustery to find a perfectly ripe tomato!

Growing tomatoes in the greenhouse is similar to growing tomatoes outside, just with a few extra considerations.

Containers: Growing plants in containers means different water requirements than when the plant is in the ground.  Tomatoes require regular watering to prevent misshapen tomatoes.  Containers dry out more quickly than the ground, so make sure to monitor the moisture level of the soil.

The easiest way to check the moisture level is to use the original hand tool, your hand!  Stick your finger in the dirt up to the first knuckle; if the soil is dry, it is time to water.

Humidity:  The humidity level inside a greenhouse is higher than outside.  Due to higher humidity, the frequency of watering may need to be reduced.  It is better to water more deeply with less frequency, than with more frequency and less water.

Temperature:  If you are growing tomatoes inside the greenhouse, keep in mind that they typically will not set fruit over 90 degrees or under 50 degrees Fahrenheit.  In the wintertime, do not expect a large harvest, since lower temperatures means the plants grow more slowly.


Desert Greenhouse Guideline:  The combination of high temperatures and low humidity in the summertime means a more watchful eye on the conditions inside the greenhouse.  I use a shade cloth, ventilation and misters, and the temperature inside my greenhouse does not go over 90 degrees on triple digit days.  Still, my tomato plants need water every other day.


Pollination: Since there are no bees inside the greenhouse to do it, you will need to pollinate the tomato flowers.  Use a knitting needle or other short slender stick to tap the branches with flowers on them.  Tomatoes self-pollinate, so the tapping will cause the pollination to occur.

Personally, I have had a lot of success using a $5 vibrating toothbrush I picked up at a discount store.  By holding the brush at the stem of the flower, the vibration causes pollen transfer.

Space: Greenhouse space is limited, so keep that in mind when selecting your varieties of tomatoes.  Small, bushy tomato plants are more compact and work well in a greenhouse environment.

If you choose an indeterminate, or vining, tomato plant, training the plant up a trellis will help save valuable space.  When the plant is young, select the main vine and prune the others.  Tie a string to the rafters of the greenhouse and with a fair amount of slack, stake the other end in the tomato pot.  As the vine grows, loosing coil the string around the vine.

Another option are the new upside-down tomato pots.  I have a couple from Topsy-Turvy, however this is the first season I have used them, so I will report back my successes with them.

Propagation:  I highly recommend growing tomato plants from seed that have resistance to common tomato diseases.  In tight quarters, diseases spread more easily.  For that reason, think long and hard as to whether or not to bring in plants from outside sources.  My greenhouse contains only plants I have grown from seed.

With these tips, your greenhouse can be a more productive tomato grower!