Growing Vegetables in a Greenhouse

GreenhouseVegetables can be grown year round even in cooler climates if you have a greenhouse.  A warm greenhouse is heated during the cold months and should maintain a minimum temperature of 55 degrees F.  Obviously this is a costly option for those in particularly cold climates, as natural gas and heating oil used to heat the green house are expensive.  However there are many people who live in somewhat warm climates, where maintaining this temperature in the winter won’t be so prohibitive.

Keep in mind that in the summer a greenhouse may get too hot, and plants won’t grow properly so ventilation is necessary.  In fact tomato plants will not fruit if the temperatures are maintained over 90 degrees F.  Many gardeners will not try to grow vegetables through the whole winter, but instead will use a greenhouse to get an early start to the season.  This way you can have tomatoes forming in June as opposed to waiting till late July or August.  It is important to choose the correct variety of a vegetable that you will be growing in your greenhouse.  There are certain varieties of tomatoes such as Legend and Siletz that will grow nicely in cooler weather.

Cucumbers, eggplant, squash, melons, carrots, lettuce, and peppers are all examples of vegetables that can be grown in a greenhouse.  There are specific varieties of these seeds that are best suited for growth in a greenhouse.  Keep in mind that you will have to pollinate your crops in the greenhouse as there are no bees to do the work for you.  You can gently shake the tomato plants when the flower petals have a slight curve to them.  Or you could use a small paint brush and manually pollinate all the flowers.

Since lettuce likes cooler temperatures it may be a good vegetable to grow in your greenhouse.  In fact lettuce grows best when the daytime temperature is around 60F and the nighttime temperature is around 50 F.  Lettuce has very shallow roots; therefore you must water your plants frequently.  Initially you can start lettuce seeds in flats, and then when they are 3 inches tall they can be set in beds with a spacing of 6 inches by 9 inches apart.

Growing vegetables in a greenhouse is definitely a challenge that only an experienced gardener should try.  You may not be successful your first season but that does not mean you should give up.  As with anything else indoor greenhouse gardening will take practice and you will have to learn from your mistakes.

12 comments

  1. Gary Linthicum

    We would like to start growing veggies in a greenhouse over the winter in Central Texas area. Is there a book I can buy to help schedule the plantings.
    Gary

  2. creed

    Gary, you’ve probably already got your greenhouse up and running by now, but for any others they may like to know, I like “The Greenhouse Gardners Companion” by Shane Smith. It has a growing guide for easy reference and there is alot of other info throughout the book that is very useful.

    Tomatoes, peas and beans are self pollinators. Not necessary to do that manually for these 3.

    I am in Central Texas & have been told you CAN use your greenhouse in the summer for growing. This is my second year. Last year I shut it down after temperatures got over 90. My greenhouse is 16′ X 13′ with a 10′ roof peak & is covered (for now) with only the greenhouse film.

    This year I am covering the roof with a silver tarp from Tractor Supply, which also will hang down as needed also on the South side. I’m also using a fan and a misting system. I feel pretty certain I can get the temperatures to 20º lower than the outside. I have tomatoes and peppers inside now that are doing VERY well. With grocery prices going up all the time, we have doubled the size of our small backyard garden. I plan to have plants maturing at different stages to ensure that we have a steady supply of fresh produce through the year.

  3. Shelly

    We have built a 15′ X 32′ greenhouse with 6 mil plastice over the top. I have two great tomato plants with fruit already on them. I have also started a hydroponic system for lettuce and some other vegetables. I’m going to try carrots and okra in large pots.
    I’ve put my tomtoes and will put my okra in pots so I can move them outside during the hot, summer months. I am in West Texas and this summer we had over 40 days of over 100 degrees. I have a tarp to put over the greenhouse in the summer and it has a screen door and one end and two screened windows at the other end for circulation.

  4. 504farmer

    I am just outside New Orleans and have been growing inside of different styles of greenhouses. I have come to learn one thing for certain: To ensure growth, you need to stay constant on ventilation and shade during the summer and the regulation of heat in the winter. You have to keep in mind what your greenhouse is made out of (glass, plexi-glass, tarpoleon, etc.). I like to use common adjustable vents like you would use with ac ducts. They are cheap and, a good battery operated fan, you can achieve good circulation and an average moisture content on ceiling. (Adjust what you are using as shade as you learn more about what temperatures you are getting.) During the winter I like my roof and walls to be plexi-glass also using the bathroom vents. Be careful what type of heat source you use as you can let the temperature get away, become too hot even for a little while and damage your plants. I hope this helps someone.

  5. Seikaneng SK Moepedi

    I am starting farming project(vegetable) and i am looking for a greenhouse,where can i buy one :size 100mx100m.

  6. faisal HASHANI

    I am working on building a greenhouse over my townhouse 5x 8 Meter. I am located at Saudi Arabia were it get very hot more than 110 for 6 month and then get down to 85, I also, want to start an Aquaponics system in side my green house. The following are inquires:
    How to build it locally and what material I should use?
    What type of cooler system I should get?
    What type of ventilation I should use?
    What should I do regarding the sun?
    What type of Aquponics system I should use? And from where I can purchase it?
    What about irrigating system are available for this type of greenhouse?

  7. Genus john

    I am looking for vegetable seeds best suited for growing in a greenhouse. Perhaps you know of some “bombproof” varieties.

  8. Nitin

    I am new comer in this field. I really like your post. Please give me more guidance gardening. Thanks.

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