Growing Guide for Hydroponic Trees (Do’s and Don’ts)

Every hydroponic grower wonders sooner or later if they can grow hydroponic fruit trees in their indoor garden. After all, a hydroponic lemon tree will thrive in a tub, and a sweet cherry tree will grow well as a tiny bonsai. 

Surely adding a tree to a hydro rig can’t be that hard?

The good news is that growing trees in a home hydroponic system is entirely possible. The trick is to choose the right tree for the right system and know the limitations of the type of tree you fancy. 

With a little research and minimal effort, you can have the same nutritious harvests you’d see from a traditional garden with your indoor hydroponic trees.

Understanding Hydroponic Trees

Hydroponic plants are generally chosen for how well they respond to the limitations of hydroponics systems. 

Leafy greens are smaller plants that don’t mind growing indoors in a water solution under grow lights. Other crops, like peppers or tomatoes, benefit from the precision of a well-tailored nutrient. Almost all of them are shallow-rooted and don’t mind close company.

Trees are a different kettle of fish entirely. They have expansive root systems as large as their spreading canopies above. The vast majority of trees take a long time to reach maturity and test the patience of even the most dedicated hydroponic growers. 

To grow full-size trees in hydroponic gardens, you must be willing to embrace the needs of the plant roots and the spreading branches. Hydroponic fruit trees can’t be crammed in a tower garden or tiny net pots. They need room to spread.

If you’re willing to accommodate the size and space they need, trees can be very rewarding to grow indoors. 

You can also view it as a short-term option. Many commercial growers get their new seedlings or cuttings established indoors before moving them to permanent planting sites. Many a mango tree or papaya plant starts its life in hydroponics before moving outdoors. 

You can also start growing large trees like pines or oak trees in hydro to keep a close eye on them when they are small and vulnerable. Once established, they can be relocated to a special spot in a traditional garden, ready to take the benefits of hydroponics into the sun and soil.

What Trees Can Be Grown Hydroponically?

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The best trees for hydroponic gardening are ones that are small enough to be kept in a container. Dwarf species are excellent choices, especially citruses like lemons, oranges, or limes (which are the perfect addition to a salsa garden). 

You can also grow banana trees and papayas from seed to harvest in a hydroponic setup.

Apples and some stone fruit do well in hydroponics, provided you prune them regularly and heavily. They can be trained into compact, elegant forms, allowing them a long life indoors or in a greenhouse setting. 

The trick is to stick to dwarf varieties or those advertised for container growing – after all, what is a hydroponics system if not a very sophisticated, attentive container?

You can also start cuttings and seeds in hydroponics for later transplanting outdoors. It’s a good way to make sure cuttings strike well.

Best Hydroponic Systems for Trees

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Without a doubt, the most successful hydroponics system for growing full size trees is Drip System Irrigation, also known as Dutch Bucket. 

This tactic involves using a growing medium contained in large plastic bags. A series of plastic tubing attached to a water pump delivers small but precise doses of nutrient solution at regular intervals.

It’s the gold standard for commercial growers, and for good reason. The container of the medium can be scaled for even the most exuberant root growth, and it uses less water for greater yields. At home, a dark plastic bag held firm with plastic tape will do the job. 

You have more flexibility if your main aim is to sprout a seeding or get a cutting to strike root. For this, they’ll do just fine in a standard Nutrient Film Technique rig or Deep Water Culture system. 

I’ve even successfully sprouted mango trees in nothing more complicated than clay pebbles (LECA) and water. 

Lastly, you can grow a hydroponic tree in aquaponic systems, allowing you to use a water basin with fish inside to recycle fish waste and give it to the tree in the form of nutrients! For this, you may need to get some additional equipment like an aquarium heater, hydroponic water pump, and hydroponic air pump, but it goes a long way toward a fruitful reward – no pun intended.

Best Growing Conditions for Hydroponic Trees

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Just as when grown in soil, different trees will have different care and growing conditions in a hydroponic setup. While there are almost no hard-and-fast rules describing how to grow hydroponic trees, there are some do’s and don’ts that you should consider following. 

Type of Tree

Do choose compact trees designed for container growth, like dwarf citrus. Compact-growing apples, pears, and stonefruit must be aggressively pruned to remain viable indoors. Tropicals like the dwarf cavendish banana and dwarf papaya are also appropriate.

Do your research into the specific tree you are growing. For example, hydroponic apple trees and hydroponic apples prefer cooler temperatures than tropical papayas. Also, some dwarf tree varieties like apples or pears require a stake for support as they mature. 

Don’t underestimate root growth. Trees can choke their own root systems if not given sufficient room, so be aware of the requirement for your species.

Growing Medium

Do choose blended mediums with good water retention and EC. An equal blend of perlite, peat, and vermiculite is ideal for almost all trees. This will hold water well while still draining as needed, and it holds nutrients well. Sterilized rice husk, wood shaving, and sand are all excellent options. 

Don’t plant trees in inorganic media. They need a degree of decomposing organic material to support plant growth and maintain suitable pH. Even when using a blend with lots of sand or gravel, ensure at least one equal part peat, coir, sawdust, or the like.

Container

Do ensure enough space for the roots of the plants. Full-sized trees, even dwarf varieties, have extensive roots. Be mindful too that the space above is important, too. Some trees benefit from pruning if you want to keep their containers close together.

Don’t be afraid to size up as your tree grows. An infant sapling will need less root space than a mature tree. Starting small and moving to a bigger container later will keep those plant roots in good condition.

Light

Do provide artificial light if growing indoors. Broad spectrum artificial lights like metal halide lamps are the most popular option. Fruit trees, especially tropicals like banana plants, need a 12-14 hour photoperiod. In early life, that fuels their growth, and later it will help them produce sweet and flavorful fruit.

Don’t “set and forget” your photoperiod. Some trees, especially European fruit trees like apples and stone fruit, need shorter day lengths to trigger the flowers that lead to fruit. 

Water

Do ensure your pH levels and temperature are appropriate for your plant type. Not only does acidic soil help protect roots from infection, but it also unlocks nutrients in the growing media.

Do consider open irrigation systems where possible. This involves allowing excess water to drain from the containers and be later discarded. This prevents diseases from spreading through your system.

Don’t overdo your water level. Drip irrigation is a precise art; too much, and you risk root disease. Small amounts at high frequency to ensure even hydration while maintaining good aeration are ideal.

Nutrients

Do check the needs of your specific species and tailor it over their lifespan. New seedlings will sprout with only water and light, but mature trees covered in blooms needs a richer solution with more phosphorus, calcium, and magnesium to ensure good fruiting. 

Don’t forget to keep your solution aerated. A hydroponic air pump will help keep your solution chock full of the oxygen that all plant roots need.

How To Start Tree Seedlings in Hydroponics

To propagate your seeds, you will need the following:

• Tree Seeds
• Starter Medium – rockwool or peat starter cubes are ideal for small seeds. A net pot of perlite or LECA is better for large seeds or pits.
• Propagation Tray with Transparent Lid (can be purchased at most garden centers and hardware stores)
• Clean water
• Weak Nutrient Solution

Step 1

Perform any preparation your seeds may require. Apple seeds often require a chill. Mango seeds must be husked and sprouted, while avocados do well when scored.

Step 2

Prepare your media by soaking overnight in clean water. Seeds are self-contained and do not require any nutrient solution at this stage. 

Step 3

Place the prepared seeds in the growing media. Insert seeds into starter cubes no more than an inch (2.5cm) deep, one seed per cube. Larger seeds can be nestled into their baskets, one seed per basket, generally with their pointed side down.

Step 4

Place your cubes or net pot of media in the propagation tray and add an inch (2.5cm) of pure water at the base. Close the tray to ensure good humidity.

Step 5

The time required for the seed to sprout will vary between species. 

Regardless, water with pure water until the seedling is at least six inches (15cm) tall. Once they are at an appropriate height, switch to a half-strength nutrient solution formulated for their species.

When your tree is a foot high, transplant it to its permanent home outdoors, in a pot, or in a larger hydroponic system.

How to Start Tree Cuttings in Hydroponics

Many tree species propagate best from cuttings. While many hydro fans concentrate on growing their own food, there’s no reason why you can’t start your ornamental trees in hydroponics for an extra boost to growth. First, willows and cedar are excellent candidates for this approach. 

To strike a cutting in hydroponics, you will need:

• Cutting
• Rooting Hormone
• Growing Medium
• Propagation Tray
• Clean Water
• Mild Nutrient Solution

Step 1

Much like seeds, some species of tree require their cuttings to spend a period in a dark place or cold location in order to strike. 

Make sure yours receive their special treatment before any attempt to sprout roots. If your cutting has large leaves, trim them to a third of their size to prevent water loss.

Step 2

Prepare your growing medium. Cuttings don’t require much hydration to sprout and are at risk of rot if kept too wet. A net pot holder or nursery pot of perlite, LECA, or Rockwool is perfect.

Step 3

Dip the tip of your cutting in a rooting compound. Ensure you get it on the base, not the cutting’s tip.

Step 4

Insert the cutting halfway into the medium and rest in the propagation tray. Depending on the size of the cuttings, you may need to use a larger clear plastic container instead of a commercial tray.

A simple method for watering is to add one inch of pure water to the base of the container and close the lid to ensure good hydration.

Step 5

For the first ten days, keep the cuttings moist but not wet. When they are ten days old, water with a weak nutrient solution. 

Step 6

Once new leaves appear, you can move your cuttings to your hydroponic system until you are ready to plant them outdoors.

Do I Need to Transplant Hydroponic Trees?

While it is possible to keep a tree indoors indefinitely, for many species, it’s best to start them in hydroponics and transplant them outdoors later. Many hydroponic fruit trees won’t produce their first crop for five or six years after germination – an awfully long time to run grow lights and pumps! 

That said, there’s nothing to stop you from keeping a beloved dwarf lemon or a small cluster of bananas indoors all year round. If you have the space and the time, they’ll reward you for your attentive care.

FAQ About Growing Hydroponic Trees