When you think of hydroponics, you often think of smaller plants like lettuce and herbs.
But we do love apples in our home, so my wife and I looked into if apple hydroponics was even possible.
Growing hydroponic apples is possible, but it requires some serious modifications of the normal procedure. They require a lot more space in the container for the roots, and the sunlight is a lot tougher to do as the apple tree grows taller. Hydroponic apples tend to be sweeter because of the nutritious water solution.
Let’s look into the details about how this may work.
Table of Contents
Issues With Hydroponic Apples
A hydroponic apple system works the same as any other plant with some notable differences.
Here are the main things to watch out for:
Extra Water Needed
Trees are big, and logic says bigger plants require more water.
This pans out with apple trees.
On average, apple trees require 5-10 times more water than a leafy green.
Be prepared to provide a LOT of water.
This means you’ll need to prepare the water by checking the pH levels and removing chlorine.
Pro-tip: Leave 1-2 lemons cut in half in the water for 24 hours to remove treatments from tap water.
Hydroponics require even more water than normal. All of the nutrients come from the water solution, after all.
In general, you need to provide 2-3 times more water than the plant normally would need in the soil.
Along the same lines, you’ll need more fertilizer and nutrition to match the higher amounts of water.
The exact amount of nutrients you give depends on the liquid fertilizer you use.
Don’t use common soil fertilizer with this unless you know how.
If you want to learn more, check out our guide for using normal fertilizer with hydroponics.
Using The Right System
There are several methods for growing plants hydroponically.
With apple trees, you’ll have the most success with a system like deep water culture.
Deep water culture is when the roots just soak in a hydroponic reservoir and get a lot of water at one time.
You’ll need to use a large container because apple trees have a vast root system.
An Ebb and Flow technique (also called Flood and Drain) will work with apple trees as well.
This is where you have a separate hydroponic reservoir that pumps the water into the tree container periodically and then drains the water back into the reservoir.
Due to the tree’s much higher water needs, you’ll need a large reservoir and a big water pump to move the large volume you’ll use.
With both of these methods, an air pump would be a huge help in keeping the water moving, oxygenated, and in a better chemical balance.
Still, it’s possible to construct hydroponics without using an air pump if you know how to set it up (click the link to learn more in our article).
Nutrient film technique is not feasible with the large root and water needs, and a wicks system won’t bring enough water to grow your trees.
Of the two possible options, we prefer the Deep Water Culture because it’s easier to do.
Since apple trees need so much more water and nutrients, you’d be checking the water all the time anyway, so you might as well skip the complex timers and pumps of the Ebb and Flow.
Tree roots are tough, too, so make sure you pick a strong plastic to use as your container.
Naturally, trees get super heavy, and the roots are thick.
For more information on safe plastics for hydroponics, click the link here.
Height And Light
With most hydroponic plants, you’ll either keep the plant in a sunny area or use an independent grow light (often LED) to provide the same rays the sun would.
If you use artificial light, as the plant grows, you raise the lights so they’re not too close.
Well, apple trees grow much higher than typical plants, as you already know.
You’ll need to make sure you have enough space for the tree to grow up in your room or deck, but you’ll also need to get a big enough and tall enough light.
The two most common options I’ve seen when the tree is grown are to either use a tall lamp with UVB bulbs or replace ceiling light fixtures with the heating/UVB lights.
We’ve also tried this Bloom Plus hangable LED grow lights with some success, though it requires more work to set up.
Of course, if you keep the apple tree outside, you won’t have this problem at all, but then you might as well just plant the tree in the soil and be done with it.
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Cross-Pollination
We live in Michigan, home of the apple tree. Apple blossoms are our state flower.
We know this instinctively, but a lot of people don’t:
You need at least two two apple trees to cross-pollinate in order to get fruit from your trees.
All plants need pollination for fruit or veggies or seeds, but many are self-pollinating.
Fruit trees, apples in particular, not so much.
They need pollen grains from other trees, so you need to double the work of your growing process in order to get fruit at all.
Both trees need to be old enough to bear fruit in order to pollinate each other, and some apple experts say the pollination is more effective the closer trees are in age.
To ensure proper pollination and fruit harvest, keep three trees instead of 2. There is a chance your tree could die at any stage in the process.
It’s not likely, but it’d be a big disappointment to get to 3 years of age, and all of a sudden be stuck with only one apple tree and no fruit.
Long Time To Production
From seed to harvest, it takes between 6-10 years for an apple tree to produce.
This is a long time, so be ready to be patient during the process.
Across these years, the tree will also grow to full size, making it difficult to keep the tree inside your home, let alone manage in a hydroponic system.
There is a way around this by dwarfing (look ahead to the next section for directions). Dwarfing your tree keeps the size down to about half of its normal size and speeds up a time to harvest to around 2-3 years.
This is still a long time, but it’s much better than 6-10 years.
If this is your first attempt at hydroponics, start smaller and check out our picks for the best AeroGarden for lettuce and small herbs.
Steps For Growing Hydroponic Apples Quickly
If you decide to grow hydroponic apples, it’s almost required to dwarf them.
We’ll briefly describe the process here. Check out the video at the end if you want to learn more about dwarfing in general.
Transfer Rootstock
While it’s possible to grow your own rootstock (a sprouted plant from seeds), it adds an extra year to the process.
Rootstocks are available at many local gardening stores or apple orchards.
Take the rootstock (preferably one with high disease resistance and production rate) and remove the soil through washing with room temperature water.
Don’t flood the roots; give it a quick rinse, gentle shake, and brush the rest with your hand.
Put your rootstock in the hydroponic pot or container. Surround the roots with Rockwool for extra support and hydration.
Just make sure you soak the Rockwool for a day ahead of time to balance the pH levels.
Learn more about using Rockwool with hydroponics.
Add the pot to the hydroponic water solution or add the solution to the bottom of the pot.
Make sure the water is only touching the roots. Aim to give a 1/4-1/2″ inch air gap between the body of the plant and the water.
Graft Apple Tree To Rootstock
Grafting is the process of attaching part of another plant to the target rootstock.
Pick another apple tree of your choice and trim off a small-growing twig at a 45° degree angle.
Trim part of the rootstock at a similar angle.
Put the graft on the rootstock and wrap them together with a grafting clip.
The plastic tape will do the job as well if you don’t want to get grafting clips.
Now, we need to encourage the two parts to combine or graft.
Place the apple tree rootstock in a dark place for 4 days. If this isn’t possible, cover it with a dark plastic bag, making sure to leave plenty of room for air.
This seems counterproductive since we know plants need sunlight, but in this case, our main goal is water.
The two parts need to combine their vascular systems, and water is a huge element of this process.
By removing from sunlight and grow lights, we’ll limit the water loss.
Watch For Grafting To Take And Transfer To Bigger Stage
After this time, check to see the grafts have taken. If it hasn’t, repeat the process.
If the graft has taken, move the plant back into sunlight or provide your grow lights.
Keep an eye on the apple tree as it grows.
If the roots outgrow the container, transfer it to a bigger one.
When half the water you put in is gone, add more water to the solution.
After the water is half gone the second time, dump the excess water, clean the container, and put in fresh hydroponic solution.
Wait 2 Years
Repeat the last step as needed for 2-3 years.
Don’t forget; you’ll want to grow at least two trees, maybe three, in case one dies.
Cross-Pollinate Artificially
Outside, bees and wind help move pollen from one tree to the other.
If your trees are inside, you need to take action to pollinate your trees.
Simulate wind by turning on a box fan once per day during the spring and when the apple blossoms are out. Place the “wind” in line with one tree pointing toward the other.
The next day, put it in line with the other tree going the opposite way.
This is a hands-off but less effective way of pollinating.
Simulate bees by using a soft-bristled paintbrush to move pollen from the anther of one flower to the stigma on the other tree.
Even better than a paintbrush is to use an artificial bee wand that vibrates like a bee to encourage the release of more pollen.
Click the link to check the price on Amazon.
Fans are easier with large trees and when you have a lot, but the manual method is more effective (though time-consuming).
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