Top Tips For Greenhouse Garden Growing | Love The Garden

Top Tips For Greenhouse Growing

Hannah Gransden's picture
By Hannah Gransden, Seasonal Pro
A Great Looking UK Greenhouse

There is a great deal of difference between gardening in the great outdoors and gardening in a greenhouse. Owning a greenhouse allows you to control the environment and create optimum conditions for whatever plants you are growing.

The main factors are the temperature and the lighting, using a heater in winter, thermometer and LED lighting, which can encourage healthier growth to bring the best out of the shape, size and taste of your vegetables. With enough practice and dedication it is possible to achieve some astounding results!

Getting the greenhouse environment right

Getting the conditions in your greenhouse right is of paramount importance. The reason for this is that getting the conditions wrong could ruin your crop, and it is quite easy to get the environment wrong in a greenhouse setting. There are 3 factors that need to be considered in order to get your conditions perfect for all types of growing.

1. Temperature

The temperature in the UK varies a great deal through the seasons, which can make it extremely difficult to control the temperature within the greenhouse. As a result you need to have a combination of heating, ventilation and cooling fans installed for the optimum environment for growth all year round.

In the winter and early spring months, it's likely you will need to use auxiliary heat to regulate the temperature for summer vegetables like tomatoes. UK winter temperatures can be between -10-15°C (14-60°F), the lower end of which can be very damaging.

During the summer months, the temperature can usually vary between 13-32°C (55-90°F). At this time of year you will need a combination of ventilation to ensure the correct amount of airflow is getting to the plants, which is vital for healthy growth, and cooling fans as it is extremely difficult to keep the temperature down on a hot, sunny day. Ventilation can vary in expense depending on whether or not you would like an automated ventilation system, which is far easier and more convenient. Adversely, you can easily get a manual-operated vent, but they do need regular checking - usually at least twice a day.

Here is a useful guide to the temperatures (degrees) that your plants need for optimum growth:

Vegetable Germination Temperature (°)
Minimum Optimum Maximum
Cool Season Crops
Beets 40° 80° 90°
Broccoli 40° 80°

90°

Cabbage 40° 80° 90°
Carrots 40° 80° 90°
Cauliflower 40° 80° 90°
Kohlrabi 40° 80° 90°
Leeks 40° 80° 90°
Lettuce (leaf types) 35° 70° 70°
Onions (green) 35° 80° 90°
Onions (dry,seed) 35° 80° 90°
Parsnips 35° 70° 90°
Peas 40° 70° 80°
Potatoes 45° 45° 45°
Radish 40° 80° 90°
Spinach 40° 70° 70°
Swiss Chard 40° 85 95°
Turnips 40° 80° 100°
Warm Season Crops
Beans 50° 80° 90°
Cantaloupe 60° 90° 100°
Corn 50° 80° 100°
Cucumbers 60° 90° 100°
Eggplant 60° 80° 90°
Pepper 60° 80° 90°
Tomato 50° 80° 100°
Squash (Summer) 60° 90° 100°
Squash (Winter) 60° 90° 100°
Watermelons 60° 90° 110°

 

2. Watering & irrigation

Regular, correct and adequate watering during spring and especially summer is essential. Although installed watering and irrigation systems are the easiest and most convenient way to water, if you have a watering can, the time and a lot of enthusiasm then this is perfectly fine! If you are starting out with your greenhouse, it is unlikely you'll invest in an electronic irrigation system as they can be rather expensive. But there are numerous simple drip, siphon, or capillary matting systems that are easy to install and use. Or attach a simple electronic timer to your tap to automate your watering via a hosepipe - especially useful when you're away from home for extended periods.

3. Lighting

Like many things, plants can have either too much or too little of light. In order to get the balance right it is necessary to use a combination of fluorescent light and special shade panels to ensure that the optimum amount of light is reaching your crop. As you probably know, the process of photosynthesis is how plants feed, which lighting plays an integral part in.

You can get lights that mimic sunlight for summer specific vegetables like tomatoes and squash, and if you are looking to take your greenhouse gardening seriously you can set up HID (High-Intensity Discharge) lights with these bulbs in.

Top vegetables to grow in a greenhouse

  • Leafy greens

Leafy greens is the family which includes lettuce and is amongst the easiest of vegetables to grow. It is a recommended vegetable for beginners to greenhouse gardening as all leafy greens grow in relatively the same way. These are also known as the ‘salad family’ which makes sense as they go well in all salads and sides.

Leafy Greens in a Greenhouse

Image credit: Rebootwithjoe.com

  • Tomatoes

A greenhouse favourite as they fairly easy to handle. They are a warm season crop that can vary greatly in colour and size. We recommend that beginners give growing these a try, they take around 65 days to harvest.

Tomatoes growing in greenhouse

  • Cucumbers

This is a slightly more complex vegetable to grow, despite being one of the more popular vegetables in a salad. In order to retain the freshness of the cucumber after harvesting you must wrap each of them in cling film/ shrink wrap.

Cucumber in a Greenhouse

Image credit: Vmo.org

  • Peppers

It is possible to grow a large variety of peppers (and chillies) in a greenhouse. Understandably they are a firm favourite as they complement most meals and are worth the little extra wait for harvest (around 70 days).

Peppers in a Greenhouse

Image credit: Agri Support Online

  • Spinach

Spinach is possibly the easiest vegetable to grow, which makes it perfect for a beginner. The fantastic thing about spinach is that it is also incredibly healthy, high in vitamins and protein (which is why Pop Eye used to eat it!). For the best results spinach should be cooked immediately after harvesting to enjoy it at its most tasty.

Spinach in a Greenhouse

Image credit: Aquaponic USA

Vertical gardening

Greenhouse Vertical Garden

Image credit: Growingagreenerworld.com

This one is for the more serious gardeners amongst you. If you have run out of space in your greenhouse but still want to be growing more in a controlled environment, vertical gardening could be the answer you are looking for! Here is a great video showing the benefits of vertical gardening in a greenhouse:

The way that he has built his vertical gardening towers in the video is just one method, there are many ways that you can set up your own vertical gardening system. If you don’t feel confident in building your own there are also commercial options available in vertical gardening.

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