Are you new to greenhouse gardening and want to grow vegetables successfully? The secret is to take advice from the experts. Doing so will help you avoid timely and costly errors that can ruin greenhouse vegetable crops before you have a chance to harvest. To start you on your journey to bountiful greenhouse vegetables, read this guide, where I detail greenhouse tips for beginners that include:
- What a greenhouse is and how to use one
- The best vegetables to grow for beginners
- Ways to control the greenhouse environment
- Tips for watering and fertiliser needs
- How to control pests and rodents
My dreams for a kitchen full of fresh, homegrown vegetables did finally come to fruition, but it took lots of trial and error. Take a shortcut to success and follow the guide below!
Greenhouse Gardening For Beginners
The growing conditions within your greenhouse are critical for both beginner and expert gardeners. When you implement the lessons from growers with more experience, you can expect your first greenhouse vegetable garden to turn out much better than beginners who don’t.
The name “greenhouse” and the history behind it is interesting. Back in the day, the same structure was a “botanical garden,” which we now think of as more massive indoor or outdoor gardens found in cities. For simplicity, I will describe a greenhouse as a building that allows a gardener to better control growing conditions such as:
- Sunlight exposure
- Wind exposure
- Moisture and humidity
- Pest or disease issues
- Precision fertilisation
Greenhouses come in many shapes and sizes, each with pros and cons depending on where you live. A greenhouse with fabric walls may not provide enough winter heat control, or a clear-glass-clad greenhouse could be a disaster in hot, sunny regions. Talk to local greenhouse vegetable growers, who can guide you in buying the correct structure for your regional climate.
How do you use a greenhouse?
Use a greenhouse as a “haven” for your plants, with these items being the most important to have:
You will need plenty of strong shelving to hold trays of seedlings and have room for mature plants. Raising plants off the ground means:
- Less bending or straining to plant, tend, or harvest plants
- Keeps root systems off possibly freezing soil
- Creates a barrier against migrating pests
- Allows better airflow around plants
Use pallets or a thick layer of gravel under large plants you plan to leave on the ground.
Even the smallest greenhouses for beginners should have ceiling and wall vents to increase or decrease air circulation. Never close off your vegetable plants entirely from the outside environment. Lack of fresh air encourages mould or fungi to grow, and you may want natural pollinators to access plants during the flowering stage.
Of all the “tricks” the best greenhouse gardeners implement, it’s taking advantage of the gadgets available to improve growing conditions. Novice greenhouse growers often overlook garden thermometers, pH testers, moisture meters, irrigation systems, automatic timers, and other inexpensive tools that increase control of your greenhouse conditions.
What vegetables can you grow in a greenhouse that are best for beginners?
Your greenhouse is set up, and now it’s time to select crops. Here is a list of vegetables beginners should grow inside a greenhouse (“*” denotes excellent winter crops):
- Lettuce or Leafy Greens*
- Scallions and Onions*
When you start gardening with these more forgiving vegetables, you can gain experience and confidence to branch out to new crops each subsequent growing season.
Beginners Greenhouse Vegetable Growing Guide
Growing vegetables in a greenhouse still requires work, and it’s your responsibility to provide everything your plants need.
Minimum temperature and insulation
A good thermometer will start your crops off on the right foot. All the vegetable crops for beginners do best when minimum temperatures remain above 18°C (65°F) at night.
For quick temperature reference, I suggest you purchase and install a large wall thermometer outside in a location that you can easily read from inside your home or greenhouse. Alternatively a stick on window thermometer can do the trick.
Inside your greenhouse, install a max min thermometer that also records the highest and lowest temperature range since you reset it last. Keep a daily log of these temperatures.
Comparing your internal greenhouse temperatures to external temperatures helps you learn how to maintain a safe minimum temperature for your vegetables during all seasons. For example, if you learn your greenhouse becomes too cold when outside temps hit 2°C (36°F), you can immediately prepare to protect your plants from damage before it happens.
You can also monitor the temperature of your Greenhouse remotely using an indoor outdoor thermometer, meaning you get to stay indoors whilst checking the temperature of your crop!
I have to confess that nothing tastes better mid-winter than a homegrown, fresh-off-the-vine tomato. To grow vegetables during winter, you’ll need to be ready by investing in a greenhouse heater. Unusually low night time temperatures can strike any time (even in temperate southern regions), shocking a plant’s development. Running a space heater during cold snaps keeps your growing plants warm. Remember to occasionally vent the space, because plants still require fresh air.
Insulation during winter?
Do you need to insulate a greenhouse during winter? Maybe. If you plan to grow winter crops, you must position your greenhouse in a spot that receives 6-8 hours of direct sunlight a day during these months, which will reduce the need for insulation. If you find your greenhouse is still too cold during winter, provide additional insulation by:
- Adding a layer of plastic sheeting or bubble wrap around walls or ceiling
- Choosing a double-wall, solid-clad greenhouse over a sheeting-style cold-frame
- Tenting row-cover fabric directly over plants
Remove extra insulation during the day to allow sunlight on your plants. Diffused light for too many days in a row can cause plants to wither. Another expert tip is to use a soil thermometer to chart temperature. Most novice gardeners aren’t aware that soil too cold or hot will kill off roots. Aim to keep soil temps between 18 to 24°C (65° to 75°F) for vigorous vegetable plant growth.
Ventilation and Air Circulation
Adequate ventilation and air circulation combat excessive moisture formation inside a greenhouse. Open doors, vents, or windows daily to bring in the fresh air or use fans to keep the air moving. Just as vegetables grow best when temperatures stay above the 15.5°C (60°F) range, they also thrive when temperatures stay under 32°C (90°F) (potatoes require temps below 26.5°C (80°F). Venting options allow you to quickly lower heat trapped inside the greenhouse when your greenhouse thermometer tells you the space is too warm.
Watering and Irrigation
For vegetable crops, a drip irrigation system can save you a lot of time and mess, especially if you often “forget” to water or have an abundance of plants. When you use a hose to water your vegetables, you’re spraying plant foliage, walls, shelving, and floors, which ramps up humidity levels. Extra water can also create muddy or slippery footing and encourage mildew growth on plants. Applying water in a slow drip directly to the plant’s soil lets you create ideal soil moisture without all the complications. Use a timer with the system to increase water savings.
Nutrients and Fertiliser
Outdoor gardens must contend with nutrient loss from heavy rainfall, invasive weeds, intense sun, or high winds. It’s much easier to control nutrient delivery to each specific vegetable plant in a greenhouse. From the initial potting soil to fertilising throughout the growing season, you can precisely deliver the perfect amount of nutrients to plants, which helps increase crop production.
Pest and Rodents Control
Rodents and pesky insects can make or break a vegetable crop, and the humid and warm conditions inside a greenhouse are very inviting. Small flies and gnats are familiar sights inside a greenhouse, so be aware that their larvae may be nibbling away at the roots inside planters with overly-wet soil. To thwart a pest infestation, inspect your plants and soil daily for aphids, cutworms, or other critters. The faster you can contain and eradicate them, the better your harvest. Use pesticides as directed, never reuse soil for new seedlings, keep humidity and soil-moisture levels under control, block rodent entry points, or use live traps to alleviate pest concerns each season.
Aim for 50 to 70-percent relative humidity inside your greenhouse for optimal vegetable growing. Install a hygrometer inside your greenhouse to monitor humidity levels, so you can quickly take action when you see it getting too high or low. In hot, dry regions, you may want to consider an evaporative cooling system made for greenhouses. This system cools the air but adds moisture back into space.
A greenhouse is usually the next step for gardening enthusiasts who want to grow crops year-round or may not have land available for a garden plot. I hope you utilise the information in this beginner’s greenhouse vegetable growing guide and see the importance of covering all the greenhouse basics before embarking on your first season of indoor vegetables. A solid foundation is the key to greenhouse gardening success!