Avoid the Most Common Greenhouse Mistakes with These Tips

Growing plants in a greenhouse, whether edible or ornamental, requires a little work beforehand. Learn from these common mistakes and have a successful growing season.


Too much humidity can allow mold spores and diseases to run rampant in your greenhouse; too little and the plants will die of thirst.

Do research ahead of time to group plants together with similar humidity needs. Grow them at the same time, or build more than one smaller greenhouse, if space permits.

Misting is an excellent way to increase humidity- find out how much your plants need.


Even in the winter, your plants may need shade from the sun. The greenhouse cover increases heat inside, so have a system to shade the plants when the sun glares.

Different shading materials are available at DIY stores and and even directly from Amazon. You can pull them over the roof, have them mounted on a pulley system against the inside of the greenhouse ceiling, or have an electronic monitor and motor system automatically pull the shades for you according to the amount of UV sunlight. This system, of course, will be more expensive than manual.

Mighty Products Heavy Duty Shade Mesh Tarp, 12 x 12-Feet


Without air circulation, the plants will succumb to disease and die. If the greenhouse has no vents, then on sunny days, even in the coldest winter, the heat will rise inside and could cook your plants.

Several manufacturers offer automatic greenhouse ventilation systems, both for AC power (hooked up to an outside outlet), or for battery or solar power. This saves you from having to run outside, opening and closing windows all day.


During the night, the winter temperatures drop dramatically. Even in areas such as south Texas and Florida, greenhouse heaters are needed when temperatures drop below freezing.

Do not use a regular house heater for your greenhouse. They are not made for a moist or outdoor environment. Only purchase a heater rated and designed for a greenhouse, and use an outdoor surge protector and outdoor rated power cord.


Growing the right plants is as important as all the rest put together. Once you’ve looked at your “dream list” of plants, you’ll realize space is the issue for your plants.

If you regularly grow vine plants, such as tomatoes, squashes, pumpkins, cucumbers, etc., you’ll want to research and find varieties bred for container growing. Bush varieties of squash require no staking or vines.

Plants that are too tall may cause too much shading of other plants. They may come in contact with the greenhouse covering, encouraging disease, mold and mildew growth.


For a greenhouse, filling containers with common garden soil would be a disaster. Soil compacts, killing the roots. In large containers, the top part of the soil dries out while the bottom of the container becomes bogged with water. The containers become far too heavy to safely lift or move.

Use potting soils that have no garden soil in them. A common practice in hydroponic culture is to grow the plants in peat moss or coir (coconut fiber).


Study the fertilizer and feeding requirements of your plants before you begin. Plants may have different requirements than the standard “feeds-everything” fertilizer. Keep a supply on hand for all your plants.

Try grouping your plants according to fertilizer/water/shade needs, or use a marker system to tell you each plant’s requirements. For example, a plant may need more shade like it’s pretty neighbor, but it’s fertilizer requirement may be different. A marker, colored tag or sticker tells you what your plant needs.

By studying ahead, your greenhouse growing season will be successful and tasty.

Want to build your own greenhouse? You’ll love these DIY greenhouse and cold frame projects from some of our favorite bloggers.

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Chad Elvington
Chad Elvington (@guest_7821)
1 year ago

Greenhouse virgin here so great info!

Frances Clarke
Frances Clarke (@guest_8603)
1 year ago

WOW!! Thank you for one site to find everything one needs to know about a plant, product, care, soil. I am amazed . Gardener’s Path is now my GO TO site for everything. I’ve spent days, in the past, researching issues related to gardening, care of trees, etc. It’s all here in one place and I can easily find that same information again without downloads, tabs etc. Thank you for your detailed information, like the type of products to use when caring for a plant, tree or building a greenhouse, on and on… all in one place. I’m amazed and… Read more »

Allison Sidhu
Allison Sidhu (@allison-sidhu)
Noble Member
Reply to  Frances Clarke
1 year ago

Thanks so much for your kind words, Frances. We’re so happy that you found us!

Jam (@guest_10498)
11 months ago

Thank you! I think my ficus yellow gems got cooked in my greenhouse. I zippered it tightly with temps going down. During the day, I partially opened to allow ventilation. Would you know if it is due to to the temperatures that go down to 39°F or not enough air circulation?

Allison Sidhu
Allison Sidhu (@allison-sidhu)
Noble Member
Reply to  Jam
11 months ago

Sorry to hear it, Jam! Depending on your growing zone, I wouldn’t count on being able to grow tropical plants like Ficus altissima ‘Yellow Gem’ outdoors in a popup portable greenhouse in the fall and winter. Where are you gardening? While these may serve to extend the season for plants suited to your zone during the summer months, a greenhouse like the one you’ve described isn’t something you can count on reliably to maintain the temperature and moisture levels required to grow topicals in near-freezing weather. Rather, they typically provide enough protection to effectively simulate shifting your conditions by a… Read more »

Cynthia Schuder
Cynthia Schuder (@guest_10666)
10 months ago

My 10 x 12 greenhouse has been a joy. Homemade with polycarbonate and steel sides, steel roof. Everything was great till one day after a thorough watering after fertilizing my soil turned white and fuzzy. I sprayed with white vinegar and water which really helped but had to do that for several days. I assume I over watered and humidity got too high. I now have a fan on low to circulate air. Which helps but lost my cucumbers. I have mostly salad veggies planted in a 3 x 12 foot bed. Any suggestions on humidity levels, I still spray… Read more »

Andani (@guest_12726)
4 months ago

Please assist me, tell me 2 limitations of local greenhouse structures that are not well developed?