When growing plants in a greenhouse, there’s a lot you have to consider. For a start, what are the best plants to grow?
If you’re looking to buy a greenhouse, then you’re well on the way to your gardening journey. Owning and working away in your greenhouse is rewarding. Especially when you know what to grow in it!
Greenhouse gardening can be fun and beneficial for beginners and experienced green thumbs alike. Except, most people have no idea what plants to start with!
So let us help you out. In this article, we’ll help you discover how to manage a greenhouse by growing the right plants.
Let’s get started!
Growing Plants Within a Greenhouse
Establishing a growing environment that maintains an ambient temperature is crucial in enhancing plant growth. This is one of the sole duties of greenhouses.
A greenhouse doesn’t just help protect plants from the cold outside. It also helps create the optimal growing environment for them inside.
Producing healthier, better-quality plants is something that all gardeners want. A greenhouse can support plants in a nurturing, caring environment. But most importantly, it provides them with the right conditions for cultivation.
Our list of five best plants to grow in a greenhouse is divided into four categories:
These plants thrive in greenhouses, making them the best choice for starters.
Top tip: To ensure your plants prosper, examine and research what conditions, temperatures, and moisture they require.
5 Best Vegetables to Grow
Vegetables are divided into two groups: cool-season crops and warm-season crops.
Let’s start off with the cool season crops. Common cool-season vegetables like:
All are great choices for cold frame greenhouses and growing in unheated greenhouses.
Growing lettuce is a cost-effective way to serve fresh salad on your table. What’s more, lettuces come in a wide variety of colours, flavours, and textures. So no matter what you prefer – take your salad to the next level!
This cool-season crop grows well in cold (duh), moist weather conditions. Sow seeds thinly, 13mm (½ in) deep, 30cm (1ft) apart in rows. When to sow depends on when you want to harvest.
For summer/autumn cropping, you can sow lettuce from late March to late July. For an earlier crop, sow in early February in seed trays then plant out in early March under cloches or plastic tunnels.
Early August is the ideal time for early winter cropping. September and October, on the other hand, are perfect months for spring cropping.
Top tip: To ensure continuity of cropping, sow a short row every fortnight.
Broccoli can be used in numbers of ways. And despite my behaviour when I was eight – throwing it on the floor isn’t one of them!
It can be eaten fresh, used in soup and pasta, and sautéed. This nutrient-rich vegetable is easy to grow as well.
So if you want to harvest broccoli in midsummer, it’s best to start indoors 6-8 weeks before the last frost date. Sow seeds 6-13mm (¼-½ inch) deep in a seed-starting mix or peat pellets.
You can even learn how to make your own seed started mix.
As a rule of thumb, when the ambient temperature is between 45°F-85°F (7°C-29°C), broccoli seeds germinate within 4-7 days. For fall cropping, the vegetable can be direct-seeded into the greenhouse summer in midsummer.
Good news – growing peas in a greenhouse is relatively simple as they pretty much watch out for themselves!
Not only peas are effortless to grow, but they’re also a tasty and nutritious legume.
Considered as a cool-season, frost-hardy legume, sugar snap peas are best in salads and mixed with other greens. To start growing them in your greenhouse, sow seeds 1-2 inches deep and 2 inches apart.
Then water the soil carefully with a fine mist until the soil is moist. For climbing, place a 3-foot trellis or plant spiral at the back of the plant. Make sure to do this without damaging the peas.
Lastly, cut off the tips slightly over the leaf node once it reaches 8 inches. This will help stimulate branching and help to prevent them from becoming leggy. This is where seedlings have stretched skinny stems and look fragile.
Carrots grow best in cool temperatures, e.g. early spring and late fall. What’s more, this wholesome root vegetable is low in calories, rich in sugar, and a good source of fibre. They make excellent healthy snacks or a quick addition to your salad bowl.
To grow carrots, the seeds must be sown thinly. The spacing should be about 6 inches apart. They can be planted in a raised bed, a larger planter, or into the ground inside or outside your greenhouse.
Germination starts after two to three weeks. During this period, remove the weaker seedlings without bruising or wounding the leaves and stems. Then water them at least one inch every week.
Once the leaves start to wither (around seven to ten weeks after sowing), it’s time to harvest them.
Top tip: the soil must be left moist before harvesting. Flatten and water the soil after.
Spinach is a great choice of plant for beginners as it doesn’t require constant high temperatures.
Its leaves are a great source of vitamins A, B, and C, and they have the highest concentration of iron and calcium among other green leafy vegetables.
Even better, spinach helps to boost your brainpower. This superfood veggie also thrives in the greenhouse and is easy to grow.
- Till the soil a week before planting and add aged manure. Spinach grows well in well-drained nutrient soil.
- Start the seeds directly in your garden or in a nursery and transplant them about three weeks after they sprout.
- Sow in shallow holes between half an inch and one inch deep and cover lightly.
- Sow about 12 seeds per foot. Recommended spacing is 3 inches apart.
- The temperature of the soil should be between 70°F-75°F to achieve an increased germination rate.
- Apply at least two inches of water every week.
These cool-season plants can adapt to chilly nights. Thus, there’s no need for heating when growing them – unless you live in a region with extremely low temperatures. Most of the mentioned plants also grow well in part-shade areas. This can reduce the need for overhead lighting.
To guarantee their full growth, particularly in the odd hot day in the early season, install a ventilation system in your greenhouse. This is to ensure the optimal temperature for the crops.
Warm-season vegetables thrive in greenhouses with steady temperatures between 55°F-85°F (12 °C-29 °C). They include:
Unlike cool-season crops, they will often need supplemental lighting, trellising, and hand pollination. If you treat them nicely, though, they can provide you with year-round summer favourites.
And the fun part is that these vegetables can be harvested in the comfort of your own backyard!
5 Best Fruits to Grow
Now, when it comes to the best fruit to grow, strawberries and melons are fan-favourites. But, you can also grow figs, lemons, and oranges in your greenhouse.
The temperature and the size of your greenhouse should be considered when deciding what fruit to grow. For instance, figs and apricots like cool conditions while oranges thrive in a heated structure.
Ideal for both novice and skilled gardeners, strawberries are easy to cultivate and they do very well in a greenhouse. The most popular choices for greenhouse growing are:
- the Cambridge favourite
- Royal sovereign
You can start sowing them in August or September with good roots in 6 inches pots. During the winter months, keep the potted ones in a cool greenhouse. Around April, they will be ready for picking.
If you’re growing cucumbers in your greenhouse, then you should grow melons too! A greenhouse can protect this fruit against strong winds and rains.
There are four varieties of melons that are ideal for greenhouse growing, and these are:
- Blenheim Orange
The best variety award has to go to Sweetheart, though. This type of melon is harder than the others and it blooms earlier.
Charentais is similar to Sweetheart, but the flavour is different. Ogen has sweet, pale green flesh but grows later than Sweetheart. On the other hand, Blenheim Orange has deep orange flesh and it grows only in a heated greenhouse.
You may begin sowing your melon seeds from mid-April until the end of May. To start with, soak the seeds in lukewarm water for 24 hours. This is to penetrate the seed and encourage germination.
Then sow the seeds around 1 inch deep directly into small pots around 3-4 inches in diameter. Whenever the soil looks dry, water lightly. Be careful not to overwater them.
Growing fig trees can mean two things: a basket of delicious fruit and the perfect summer shade!
Figs thrive full in the sun and make tasty fruits. They also produce broad leaves in spring, providing natural shade for your plants.
One of the amazing things about this tree is that it loses its leaves just in time for fall as well. This means it retreats in time to give your plants more sunlight. What’s more, they’re a dry tolerant fruit and can withstand inadequate ventilation environments.
If you’re planning to grow a fig tree in your greenhouse this year, the best time to do it is in early spring while the sapling is still dormant. Figs also thrive if planted in the summer or fall. When it comes to cold climates, it’s better if a fig sapling is in the ground, rather than a pot.
The best place to plant fig trees is in the middle of raised beds. This is to ensure that there’ll be plenty of space for root growth and optimal shading capability.
Lemons and oranges
Once you begin harvesting greenhouse-grown lemons and oranges, you’ll never look at the ones in supermarkets the same way again!
They’re easy to grow and can fill up your basket with fresh fruit possibilities year-round.
Both belong to the broader category of citrus fruits, and they’re the easiest citrus trees to grow. You can grow orange and lemon trees in terracotta pots in a sheltered, sunny spot. Keep in mind that they do best in high humidity.
In the summertime, water them at least once a week. If possible, use rainwater. But if only tap water is available, let the water stand for 24 hours to let any chlorine evaporate. Water sparingly in winter.
Feed them weekly with liquid seaweed and a citrus fertiliser. When the spring comes, thin out the centre so light and air can get in. Remove any dried branches or any parts that look thin or lack vigour.
5 Best Herbs to Grow
Herbs make an exciting and healthy way to incorporate fresh greens into your food. Not only that but they add natural decor to your home.
If you wish to create a year-round herb garden in your greenhouse, it’s best to know which herbs do best in these growing conditions. Listed below are our top five herbs for greenhouse gardening.
Come on – you’ve heard about this astonishing herb before. Rosemary is a must-have in every culinary spice rack!
This herb is also ornamental, which makes it a lovely decorative plant. Thanks to its aromatic and flavourful leaves, rosemary is one of the tastiest herbs out there.
It’s surprisingly easy to grow them in a greenhouse, too! You can either start from seeds or cuttings. Plant them about ten weeks ahead of the last spring frost.
But before planting, soak the seeds for four to six hours. This is to soften the seed coat as well as prime them to sprout.
Rosemary does best in well-drained soils with temperatures ranging from 65°F-75°F. The preferred spacing is 3ft by 3ft. Considering they love light and humidity, growing them in a terracotta pot is a good call.
Pick a sunny location to provide them with enough sunlight. The herbs should also be watered using the deep watering method. To keep humidity high around the plant, spritz regularly with a spray bottle of water.
Top tip: Trim them after the first flowering to encourage the herb to grow bushier.
Parsley is loved by gardeners and chefs the world over. For one, this classic aromatic herb is low-maintenance and easy to grow in any garden, including in greenhouses.
Parsley is also rich in Vitamins A and C and Iron. This flowering herb has been widely accepted as a traditional remedy for absorption, getting rid of urinary tract infections, or even used for freshening breath. (Not with the same plant though!).
Additionally, this herb is a common ingredient in East European and Mediterranean cuisines. It can also be mixed with dill, basil, mint and other herbs when preparing pestos.
When planting parsley in your greenhouse, take note of the following:
- You can plant parsley in containers, hanging pots, raised beds, or directly into the ground
- Recommended spacing is 6-8 inches between the seeds
- Well-composted manure is ideal. This is to enrich the soil before planting the herb
- Soak the seeds a day before planting, preferably in warm water overnight
- Remove any seeds that float. Place the rest onto a paper towel or cloth to dry, and plant immediately
- The optimal temperature should be between 65°F-75°F
- Fresh parsley must be thinned out or transplanted when it reaches two to three inches high
Parsley also loves sunlight. Other than your greenhouse, you can grow them in a sunny kitchen window.
Also known as Cilantro or Chinese parsley, this deep green herb is commonly used to enhance the flavour of South American, Arabic, and Asian dishes.
When growing this herb in a greenhouse, prepare a patch of soil. Alternatively, if you have slab bases, you can grow cilantro inside hanging pots or raised beds.
Add well-composted manure to the soil. Next, sow the seeds about a quarter of an inch deep. Sow seeds 6 inches apart in rows about a foot apart.
This savoury herb also does well in dry weather. Meaning, there’s no need to keep the soil soggy after the plants germinate. Lastly, if you want a fresh supply for the entire growing season, plant fresh batches every two to three weeks.
Thyme is a beautiful herb with lovely leaves and flowers. It also comes in different varieties like golden-scented, garden, and ground-cover thyme. All can be used as culinary or medicinal herbs.
The herb’s little flowers attract beneficial insects as well, including native pollinators like honey bees and wasps. Plus, you can plant them with cabbage, aubergine, potatoes, and strawberries.
It’s thought that thyme can help repel cabbageworm, flea beetles, and tomato hornworms. This makes the herb an excellent plant companion.
To start thyme from seeds, plant them in little containers roughly two inches apart. Then spread a light coating of potting fertiliser.
Transplant the young seedlings into their final locations. The ideal spacing is 12 inches apart and in full sunlight. Considering that thyme grows slowly during its early stages, it’s best to mulch with straw to help suppress weeds.
This herb needs to be watered regularly. But be sure to allow the soil to dry first before doing so. Ideally, water them about two inches every week.
Packed with Vitamins K and A, basil is a nutritious and delicious herb. It’s rich in minerals too, including manganese, calcium, copper, and magnesium.
In addition to being jam-packed with vitamins and minerals, this herb also has medicinal properties. It’s an anti-inflammatory and an effective pain reliever.
Sounds like a great reason to grow some! With steady temperature regulation, light, and moisture, you can start growing basil in your greenhouse.
It grows well in rich aerated soil. The seedlings are then expected to appear within two weeks.
When this warm-weather herb has more than five ‘true’ leaves, transplant it to its final growing area. They should be planted 4 inches apart to develop properly.
Make sure to water them regularly to avoid untimely blossoming. But avoid over-watering, as the plant will become more susceptible to damp.
Top tip: Since basil is quite tolerant to dry conditions, expose it to intense daylight 6-8 hours a day to grow healthy.
5 Best Ornamentals to Grow
Providing a controlled environment, greenhouses also make an ideal place to tend ornamental blooms. But before you embark on your growing greenhouse flowers adventure, keep in mind the special needs of these plants.
These include sunlight, temperature, water, and more. By considering these, you can plan or position your flowers accordingly in your greenhouse.
For the best types of flowers to begin your greenhouse gardening, consider our top five ornamental plants:
Geraniums aren’t just pretty flowers. Their ability to lower stress levels and antibacterial properties make them a popular choice for bedding in gardens.
This native South African plant is loved for its cheery flower clusters and decorative leaves. And many gardeners appreciate just how easy flowers are to maintain.
When the gloomy winds of winter come, these jolly geraniums can still be grown in a greenhouse. First, select pots for them. If you wish to use the old ones, be sure to sterilise and disinfect the pots to prevent bacteria from infecting the new plants.
Fill the garden pots with three-quarters full of amended potting mix. Add water-soluble fertilisers at planting time and every after two weeks.
Add a seed to each hole and cover them with the displaced soil. You can use a chopstick to create a hole. Push it ¼ inch deep into the pot.
Lastly, water the seeds until the water runs through the draining hole.
Top tip: Mist geraniums lightly every morning with distilled water. This is to encourage growth and reduce the risk of foliar disease.
If you want to brighten up your greenhouse with lovely pastel colours, growing petunias is your best bet! And there’s a bonus – cultivating them is easy.
Petunias bloom best in full sun. These attractive flowers like fertile soil which drains well and is neutral to slightly acidic (pH 6.0 to 7.0).
Spread a 2- or 3-inch layer of organic material to mulch the soil. Organic mulch can suppress weeds, keeping the soil moist. This also improves the texture as it gradually decomposes.
By midsummer, the plants will start to get leggy and spindly. This causes the stems to produce fewer and smaller flowers. What you can do is cut each stem back by half to revitalise the plant.
When it comes to annuals, it’s not just the flowers that matters, it’s the foliage, too. And speaking of foliage, Coleus are some of the best-growing varieties. Did you know that the best leaf colour is achieved with morning sun and partial afternoon shade?
In fact, many varieties do well in both shade and part-sun.
Planting this colourful and patterned plant after the danger of frost has passed is ideal. You’ll want to make sure you’re growing them in soil temperatures that have warmed sufficiently. Evening temperatures should be above 60°F.
Feed the plant with a water-soluble fertiliser, especially if they’re in containers.
Planning on putting a big show on with some chrysanthemums in your landscape this year? Save your money and put your greenhouse to work!
There are around 150 to 200 different species of this beautiful flowering plant. So it’s important that you have the specific species and colour in mind before planting. Varieties including Paris daisy and Marguerite can thrive in a greenhouse.
But before you introduce chrysanthemums to your greenhouse, clean the structure with a commercial disinfecting product. Sterilisation is a great way to eliminate any fungal and bacteria infections.
Set the greenhouse’s thermostat to 68°F-75°F during the growth period or until the plant begins to bloom. Decrease the day and night temperature to 65°F once the flowers begin to bud.
Water chrysanthemums once or several times a day, depending on the greenhouse temperature to keep soil moist.
Nothing’s fancier than growing pansies in a garden or in a greenhouse! These bright and cheerful flowers can provide life and colour in flower beds where none may have existed.
Originating from the small and delicate variety Johnny-Jump Up flowers, pansies are part of the Viola family. This blooming type of flower boasts a fine and frilly texture in beds.
Today’s hybrid versions are more adaptable to heat compared to those with larger blooms in the past. Their preferred daytime temperature is in the 60°F range while around 40°F in the nighttime.
Pansies can be started from seed or purchased as seedlings. If you plan on growing them, they may be nurtured with spring and winter-blooming bulbs, such as Tulips and Daffodils.
Lastly, bear in mind that pansy plants are biennials. This means that if they’re grown from seed, they may not be able to bloom or flower until the second year. Nevertheless, the waiting period is worth it.
Top tip: Water 1 inch weekly and deadhead any damaged or sickly looking flowers pansies for a longer period of blooms.
There are dozens of things to consider when starting a greenhouse garden. When it comes to what you can grow, the possibilities are endless, that’s for sure.
So start with our five plants from each category. They’ll help you develop your knowledge and make your learning process easier. And after you’re done with this guide, start planning ahead with what to grow in your greenhouse in winter.Shop Greenhouses