Trees grow in the ground, sometimes in (very) large pots. Or very small ones in the case of bonsai trees.
They need soil and sunlight; they’re adapted to weather and climate and the variations that come with both. Growing trees with hydroponics sounds impossible when you consider that trees can live for over ten thousand years and grow to over 380 feet tall, right?
In most cases, right. You cannot grow an oak tree or a Great Basin bristlecone pine hydroponically, but there are some trees that are suited to the approach.
To find out which trees may be grown successfully in a hydroponic system, we first need to understand what hydroponics is.
What is Hydroponic Growing?
Essentially, hydroponic plants are grown in water and a liquid-nutrient solution: no soil. Long-used in commercial food production — lettuce, for example — hydroponic growing is rapidly gaining in popularity with individuals looking to grow their own food without the need for outdoor space.
There are other advantages to a hydroponic growing system, with bigger yields, faster growth, and year-round growing seasons being the most significant, but not all plants are suited to being grown hydroponically. There are also some downsides to hydroponic cultivation, some of which are particularly relevant to trees.
Growing Trees Without Soil
Although the vast majority of trees are not suited to hydroponic growing, there are some exceptions. For the most part, you would be looking at dwarf trees: those specifically designed, through selective breeding or grafting, to be smaller than their full-size counterparts. That aside, there are some practical considerations to think about if you want to investigate hydroponic trees.
Size
Size will always be an issue as even small trees can get bigger than your countertop can accommodate.
Any tree is a lifelong project, so before you venture into planting in water or soil, it’s best to think ahead and make sure that you have enough space not only for a seedling, but also for a tree of 10 feet tall or more. In terms of hydroponic growing, it’s also critical to take into account the lifespan of trees.
Age
If you plant a tree in the ground, it will mostly look after itself once it’s established. However, if you grow a tree hydroponically, that tree will be entirely dependent on you (or someone who wishes to take over its care) for its entire life. Which may be longer than yours!
There’s very little information on whether hydroponic trees can later be planted in the ground, so do comprehensive research and plan ahead if you decide to embark on a hydroponic adventure with a tree.
Resources
Electricity and water usage are among the main considerations when growing trees in a hydroponic system. Electricity is required to keep grow lights, heaters, humidifiers or dehumidifiers (depending on the type of tree you’re growing and its requirements), filters, and air pumps working.
You may also need a fan or some sort of ventilation system to prevent the growth of mildew and mold, and you’ll need to be aware of the risk of parasites and how to prevent an infestation.
The water in which hydroponic plants are grown needs to be changed, on average, every few weeks with regular top-ups every few days. A tree-sized plant (usually, a tree, but more on that below) will have significant water requirements.
It will also consume a significant quantity of nutrients, and as all hydroponic nutrients need to be purchased and regularly replaced, the cost of growing something as large as a tree, even a dwarf one, may become prohibitive.
There are also other associated (but necessary) products, like those to manage water pH: something that’s absolutely essential in hydroponic growing.
Cost
And of course, the cost of setting up a hydroponics system that can accommodate a tree may be out of the reach of many individuals. Due to the increasing popularity of hydroponic growing, there are many home growing kits available to allow people to try hydroponics easily with herbs and salad vegetables. However, those won’t quite work for trees!
Reason
Hydroponic trees are a big investment in terms of space, time, and money. You’d have to have a good reason to make the commitment to undertake hydroponic cultivation of something as big and long-lived as a tree. The trees on which growers seem to focus, therefore, are trees grown for their food value: fruit trees.
Trees That Can be Grown Hydroponically
1. Citrus
Citrus trees, including lemon and orange, can be grown hydroponically with great success. The best varieties of lemon are Lisbon and Meyer, and Valencia, Hamlin, and Dream Navel oranges grow very well in a hydroponic system. Citrus trees can live for between 50-150 years.
2. Mango
Mango can be cultivated hydroponically if you choose a dwarf variety and if great care is taken to ensure that the tree doesn’t get too big. Full-size mango trees can grow to over 100 feet tall and have a canopy of over 35 feet in width, so this really is necessary to consider!
It’s also important to bear in mind that mango trees can live for over 100 years whether they’re small or enormous.
3. Banana
Believe it or not, it is possible to grow bananas hydroponically. (And they’re technically not trees.) However, as some banana varieties can grow to 23 feet tall or more, you’d certainly need a dwarf variety. Dwarf Cavendish, Super Dwarf Cavendish, Lady Finger, and Gran Nain are among those recommended.
Banana plants don’t grow like trees, so lifespan isn’t an issue: each flowering and fruiting stem will only live for some months, but will produce “pups” from the base of its stalk.
4. Fig
Hydroponic growers have had enormous success and excellent harvests growing figs. One variety that seems to work well and is self-fertile, something very important unless you want more than one fig tree, is Brown Turkey: these trees can live for about 200 years.
5. Papaya
The dwarf variety that hydroponic growers seem to recommend the most is the Red Lady. Like the banana plant, a papaya plant isn’t strictly speaking a tree either, but it can grow up to 30 feet tall, hence the need for a dwarf variety. Papaya plants are relatively short-lived.
6. Can you grow apples hydroponically?
Yes! Apples can be grown with hydroponic cultivation. Growers say that their trees grow faster and produce sweeter-tasting apples than those planted in the ground. However, as with the trees and plants mentioned above, it’s essential to grow dwarf varieties. There’s another consideration with apple trees too: fertilization.
Some plants and trees can pollinate themselves; this means that there’s no need for two of them for fruit to form, as each plant contains both the male and the female parts. Plants grown in isolation from nature and pollinating insects might still need a little help from you, but they have everything biological that they need already.
Most apple tree varieties, however, are not self-fertile. You will need two, or maybe even three, compatible cultivars in the same or adjacent Flowering Groups.
This might make hydroponic apple growing a little less practical than hydroponics with other fruit trees (and tree-like plants), as everything has to be multiplied by two or three: space, electricity, water, nutrients, and of course, cost.
Still, when done properly, hydroponic cultivation of apple trees can be very successful in terms of the quantity (yields) and quality of apples. Bear in mind though that, when grown outside in the ground, apple trees may live for hundreds of years.
7. Avocado
Although full size avocado trees can reach more than 80 feet in height, it is possible to grow them hydroponically. However, avocados are known for being a bit sensitive!
The only true dwarf variety is the Wurtz, but this is also known for being difficult to grow. Avocado trees in general have lifespans of several hundreds of years.
Another thing of which to be aware with avocado trees is that they’re not really self-fertile even though they do often have both male and female parts. Many varieties of avocado, including the Wurtz, do require another compatible variety to produce fruit.
So, like with hydroponic cultivation of apple trees, all of the requirements and costs for growing avocado trees hydroponically have to be multiplied by two or three.
Hydroponic Trees and Growing in General
If you have sufficient resources (and that includes financial resources), it is possible to grow certain trees hydroponically. Growers say that there can be a steep learning curve, so read, read, read, and learn as much as you can before you begin with real, living plants.
While hydroponic cultivation done properly and responsibly can have major benefits overall in terms of its sociological and ecological impacts, from feeding more people to reducing pesticide usage, it’s not a panacea. It’s not a practical solution for everyone, nor can all plants be grown hydroponically, as mentioned above.
There is also the extremely important issue that hydroponic growing does nothing to contribute to soil health or increase biodiversity, so while it may be extremely useful for food production in certain cases, it won’t solve all of our environmental problems.
Ultimately, trees belong in the ground. Their contribution to habitat preservation and biodiversity, soil health, carbon dioxide management, and the well-being of a wide variety of ecosystems cannot be underestimated.
They’re also vital for our health and well-being. But if you’re living in a place where planting a tree in the ground just isn’t possible, then a hydroponic system might be the next best thing for you.
There are lots of grow guides available in print and online, so do lots of research. Different trees have different needs and prefer different growing systems (there are multiple methods and media!), so match what you need with what you can provide.
It might be an idea, if you are considering growing a tree with hydroponics, to get at least a bit of practice first with something smaller. Look into the kitchen grow kits for salad or herbs, and test your green thumb there. It will at least give you an introduction to the basic principles of hydroponic growing, even if growing trees is a bit more complex.
Enjoy your growing, wherever you do it!
Featured Image by Jatuphon Buraphon at Pixabay
