There’s nothing like the smell from peeling the skin off a fresh orange to put you in a good mood. That spritz of zingy citrus scent is enough to transport you to sun-drenched orchards. But oranges, and other citrus trees, can be grown in an indoor environment all year round, hydroponically.
Growing trees hydroponically will always be challenging as they require loads of water, light, and space. For this reason, all hydroponically grown trees need to be dwarf trees.
When looking for dwarf trees, you must investigate what type you need for your hydroponic setup.
Let’s investigate what type of dwarf orange tree is the best and what rootstock you need to select for the best results.
Dwarf Orange Trees
Citrus trees have a relatively flexible root system and can conform to suit your needs. This means that dwarf orange trees will be easier to find than other dwarf trees.
Dwarf trees don’t naturally occur and are a product of human intervention. These trees grow to their full size when reaching only 18 - 22 feet. But even at this small size, they will produce full-sized produce.
Commonly, dwarf oranges are marketed toward those living in small homes with minimal space in their yard. Growing them in the soil requires little to no maintenance. As long as the tree has loads of sun, moist soil that drains well, and is fertilized regularly, you should be good to go.
The same is basically true for hydroponics, except that you need to keep a light on the trees and manage the nutrients in your system.
There are several varieties to choose from when considering growing a dwarf citrus tree in your hydroponic system.
Citrus trees are perfect candidates for creating cloned dwarf versions of themselves. And there’s no need to purchase a new rootstock and graft a cutting yourself.
Young citrus trees, like your hydroponically grown orange, are a perfect candidate for softwood cuttings. These are the branches that are not brand new shoots or a lot older and established; they are green, semi-established branches. If it is hyper-flexible, it’s too young; if it snaps, it’s too old. With cuttings, you will shorten the waiting time for your first fruit.
If you want to clone the plant, just cut these softwood branches off and remove the lower leaves. Then you can place them into a small pot with potting soil and fertilizer and watch them root. Make sure to put them in a sunny window.
But if you can’t find the exact dwarf orange tree you want at your local garden center, you can perform a grafting technique, joining a cutting (also known as a scion) to rootstock that suits your growing needs. This also cuts down the waiting time for fruit.
When mating the rootstock with a scion, you will be blending two different plants with distinct properties. Your rootstock could be excellent for handling colder conditions, while the scion promises to deliver a specific type of fruit.
Make sure to cut the mating branches at 45° and use sterilized equipment to lower the risk of transferring diseases. Bind them together, using plastic tape. Make sure to wrap tightly.
Grafting takes time to master, expect to fail a few times.
The alternative will be growing an orange tree from seed, and it can take up to ten years before it starts producing fruit.
Now that we know the type of plant required for growing oranges hydroponically. Let’s focus on what conditions orange trees love.
Best Growing Conditions For Hydroponic Orange Trees
Originating from the northeastern region of India, they are now grown worldwide. Orange trees have been domesticated for thousands of years. According to research conducted in the 80s, oranges are the most cultivated fruit tree in the world.
Now you can find them in most tropical and subtropical climates worldwide. All citrus trees belong to a single genus of Citrus and are almost entirely interfertile. This means cross-breeding is pretty straightforward and commonplace.
Citrus trees do well at moderate temperatures of between 59.9 °F and 84.2 °F. Oranges are sensitive to frost, but you can move them indoors for the chillier months. To combat this in the early part of the 20th century, farmers developed a smudge pot, which is a pot and chimney device that burns oil to keep the frost from forming. Luckily today, this can be replaced by an intense grow light.
Oranges need lots of water, fertilizer, and a good draining substrate.
Outdoors in an orchard, oranges will require up to 40 to 45 inches of rain annually but they can tolerate up to 60 inches. With extreme downpours, the trees will need the water to drain away. If not, they can suffer from mold and root rot.
In drier conditions, the fruit will develop a more intense color. At the same time, there won’t be as many oranges on the tree.
Now let’s focus on the requirements for growing an orange tree in a hydroponic system.
Hydroponic Requirements for Orange Trees
When growing orange trees, you must choose between a deep water culture (DWC) system or drip irrigation. With growing trees hydroponically, we’d suggest selecting the drip irrigation system.
Drip irrigation allows for more flexibility regarding pot size. Also, if you are required to move the trees, you can with a dripper system.
Check out our top recommendations for purchasing a hydroponic system: Top Rated Hydroponic Systems
A major consideration is also the height of the grow light.
With trees, the height and size of the plant determine how you install the grow light. The gardener will need to adjust the grow light throughout the early stages of growth.
The next factor is citrus trees require a lot of sunlight.
Choosing a full-spectrum LED light will assist with this. Also, it will help with your power bills. Your orange tree will require at least six to eight hours of sunlight daily, but the optimum level is 12 hours.
With citrus fruit, you may be tempted to maintain the pH level reasonably high, but reducing the pH level from 7.0 to between 6.0 and 6.5 results in better absorption of nutrients such as potassium, phosphorus, calcium, manganese, zinc, and iron.
Nutrients need to be an even 20-20-20, so a generic all-around fertilizer will do. The growing medium will likely be a coco coir substrate, with the smaller trees rooted in Rockwool. You can vary these growing mediums between stone wool or rice husks, but as long as it allows for good drainage you should be good.
The constant flow of water can often bring down the temperature in a grow room. For this reason, you might want to invest in a small aquarium heater to ensure the temperature doesn’t drop too low.
Orange trees are also not a fan of high humidity, which will require you to purchase a small fan to circulate the air around the plant. Humidity can lead to mold and fungi forming on your tree.
Now it’s time to walk through the process of setting up your hydroponic system.
How To Assemble Your Orange Tree Hydroponic System
While many suggest using a DWC system to grow an orange system, the margin for error is more significant when compared to a more straightforward drip irrigation system.
With a drip irrigation system, you will connect the drippers to the water source, dripping the nutrient solution at the tree's base. You can always add more drippers if required.
The potting medium should allow quick drainage through the substrate into a catchment area that will flow back into the main reservoir.
Set the water timing to five to eight times a day, with watering intervals of 10 minutes. Also, ensure that the ventilation works so mold and fungi don’t take hold.
Harvesting is a simple process of picking the fruit straight off the tree. You can leave the fruit on the tree for months, keeping them fresh. But the longer you wait, the longer it takes for the next flowering cycle to occur.
And to ensure the fruit does develop, you will need to hand pollinate the flowers on the trees. A paint brush will do to transfer the pollen from flower to flower.
Now You Know How Grow Oranges Hydroponically
Growing a tree hydroponically will mean spending more than usual on your initial setup. You need more water, fertilizer, space, light, growing medium, and more parts for the system.
But you get it right; you could harvest a crop of oranges all year round. For those lusting for that zesty citrus aroma and fresh taste, then growing your oranges in a hydroponic system is worth it.