How To Grow Grapes In a Greenhouse
Thursday, 27 August 2020 | Matt
Did you know that grapes can be grown in a greenhouse even if you live in a cooler climate? It is surprisingly easy to grow grapes in a greenhouse, if you follow some of our top tips!
It is not absolutely necessary to grow your grapes in a greenhouse but it will yield a better crop. The other advantage to growing in a greenhouse is that your grapes will be tastier and generally of a better quality.
It is important to remember that grapevines take up A LOT of room. If you have a smaller greenhouse you may want to grow only one vine. Plant your vine in a planter or a tub so that the roots will be restricted and your vine will not get so large. Take the time to research your choices when deciding which type of grapes you will grow.
Best Grape Varieties to Grow In A Greenhouse
The most popular choices of grape vines to grow in a greenhouse are Thompson’s Seedless, which produces a seedless green grape, and the Black Hamburg, which produces a larger, darker grape. Both are delicious and well worth your time.
How To Plant Grapes In A Greenhouse
You have three choices when deciding how to plant your grapes in a greenhouse. If your greenhouse is small and you are able to make a hole in the bottom or top of your greenhouse you can actually plant your vine with the roots outside. The second option is to keep the roots of your vine inside the greenhouse. The third choice, to plant in a tub, is good if you would like to plant several grape varieties or if your greenhouse is small. We will start by exploring how to plant your vine with the roots outside of the greenhouse.
Growing With Roots Outside (recommended)
Grapevines have substantial root systems that can take up a vast amount of space in a greenhouse. When you plant your vine with the root outside you allow more space in your greenhouse and you also allow the roots of your vine to grow and find moisture and nutrients outside your greenhouse, meaning you will have to water and fertilize less often.
When planting with the roots outside, you begin by planting your vine just outside the greenhouse and then train it or coax it into the greenhouse via a hole in the bottom or top of the greenhouse. You may be able to remove a brick in the floor of your greenhouse to make this process easier. If you don’t want to make a hole in your greenhouse, consider planting your vine with the roots inside.
Growing With Roots Inside
The benefit of planting your grapevine with the roots inside is that you may get grapes earlier as the soil will be warmer. If you decide to plant with the roots inside, you will need more space and your grapevine will not be able to spread out and find its own moisture and nutrients so it will require more watering and general care.
Planting in a Tub
Grapevines will grow extensively if they are allowed to. If you plant in a tub the roots of your vine will be unable to spread, therefore limiting the growth of the plant. This may be a good thing if your greenhouse is on the small side. If you decide to use a tub planter, ensure that there is good drainage. You should be watering your vine regularly. It is also important to fill your tub with good quality compost fortified with nutrients. If you choose to grow your grapevine in a tub there is no problem with taking the tub outside when the vines have matured. The vines themselves are actually pretty resilient.
It is important to prune your vines each year down to only 4 - 6 stubs. Proper pruning will help ensure your vines are manageable and the fruit continues to grow and flourish. Most people do not prune their grapevines enough, be ruthless in your pruning!
Ongoing Care for Grapes
There are several crucial steps to ensuring your grapevines are successful, including feeding, watering, pollination, pruning and taking care to ensure your plants don’t get infected with disease. In the spring, before your vine starts to grow sprinkle a little bit of bone meal and fertilizer around the roots. Continue to feed your vine every three weeks until the grapes start to ripen. When you see the colouring process on the grapes it is time to stop feeding your plant. This process will ensure the sweetest possible taste.
Your grapevine will need to be watered regularly. If you planted with the roots outside you can get away with watering every week but if you planted in a tub or other container you will need to water more frequently. Pay attention to the weather, if you are experiencing a stretch of dry weather don’t forget to water more often.
It can be helpful to hand-pollinate your grapes. Hand-pollination is easy to do, simply wait until the vine starts to flower and give the stem a good shake. Your goal is to transfer the pollen between the flowers. It is best to do this when your greenhouse is warm and well-ventilated.
Whether you plant your grapes with the roots inside or outside it is essential to prune. People often use the rod and spur system of pruning for their greenhouse grapes. The Guyot system is more popular for outdoor grown grapes. Whichever way you prune, don’t be timid, you will want to remove almost all of the wood from the previous year’s growth.
Continuously check your grapevines for signs of disease. Powdery mildew and grey mould are the most likely culprits. You can protect your grapes by ensuring you have good ventilation in your greenhouse and pruning back your vines to limit overcrowding. You can also look for mildew resistant grape varieties or use a fungicide.
You can also learn how to plant tomatoes in a greenhouse here.