Growing potatoes is a staple crop that will reward gardeners with an abundant yield. While potatoes are synonymous with soil, they can be grown in a hydroponic setup.
Utilizing hydroponics for potatoes can be tricky, as they will need to be monitored constantly.
While one of the main reasons for growing a crop hydroponically is that it saves on space, growing potatoes in these systems won’t deliver on this promise as you will need a system that will accommodate their tubers.
Potatoes in hydroponic systems will need the maximum amount of growing medium. But those are details we’ll go into at a later stage.
One huge benefit of keeping potatoes in a hydroponic unit is that they will be grown in an environment completely free of soil-based diseases. Which, historically speaking, has been a significant issue.
Now, let’s learn more about potatoes.
Background Information About Potatoes
Native to the Americas, the potato is a starchy tuber of the plant called Solanum tuberosum. The plant was domesticated somewhere in the region of southern Peru and northwestern Bolivia between 7,000 and 10,000 years ago.
Since then, thanks mainly to selective breeding, there are over 5,000 types of potatoes. Also, potatoes are a part of the nightshade genus, which surprisingly means that tomatoes are a part of the same family.
As a staple food, potatoes are nutrient-dense. The plant, not the tubers and fruit, contains a toxic compound called glycoalkaloids, which can harm humans. But generally speaking, the seed potatoes you will use in your system won’t have much of this compound.
What are seed potatoes?
What are Seed Potatoes?
Created from specifically cultivated tubers, seed potatoes are grown to be disease-free to ensure your crop is healthy. These seed potatoes are grown in selected environments with brutal winters to ensure that pests are killed off naturally and in the summers they have long sunshine hours.
Currently, only 15 states can produce seed potatoes in the USA.
It’s essential to ensure that your seed potatoes are covered and not exposed to sunlight, as exposure to light will produce green tubers that can be toxic.
While you might be tempted to use a sprouting store-bought potato, they can contain diseases that will affect the entire crop.
Now that we have some background let’s talk about the optimum growing conditions for potatoes.
Best Hydroponic Growing Conditions For Potatoes
Potatoes are a thirsty crop, requiring loads of watering. Luckily for you, yours are in the water, but be aware that they will rot if they are soaking in water. As a fruiting crop, it also needs sunlight in abundance.
Make sure your potatoes have a minimum of 6 hours of direct sunlight, but you want at least 10-12 hours for the best results. If you are growing indoors, use a full-spectrum hydroponic grow light to boost productivity.
The best pH range for potatoes in a hydroponic system is between 5.8 and 6.2. Nutrient electrical conductivity (EC) is at its best between 2.2 and 2.1 dS∙m−1.
Temperatures in the growing area should be kept between 46.4°F - 73.4°F. You’ll want to ensure that humidity is relatively high and there is enough ventilation to prevent mold from getting a grip.
Potatoes can suffer from several issues, like fungal infections like blight. If your crop is infected with blight, the leaves and stem will blacken go limp.
Other major pest issues are aphids and Colorado potato beetles that have yellow and brown stripes down their hard shells. You can battle these pests by washing down the foliage on sunny days with a hard stream of water.
Or you can use your hands to remove the pests. Which is labor-intensive but will ensure your crop is safe.
The fertilizer routine is pretty basic, with nutrients added once a week. This fertilizer should be general-purpose, with no need to purchase anything more specialized. Make sure that the label on the nutrient packaging says 20-20-20.
But arguably, the essential part of growing potatoes is their growing medium.
Hydroponic Potato Growing Medium
The main issue with growing potatoes in hydroponic systems is they usually produce smaller tubers. This is due to the weight of the growing medium, as this pressure will affect the general size of the tubers.
For this reason, when growing potatoes in soil, you want to ensure they are well-tilled. Good potato soil will provide a lower pressure on the tubers, which in turn allows for the tubers to grow bigger. But, you don’t want the growing medium to be too light as your tubers will grow as large as they can, which means a crop that hasn’t distributed its nutrients properly.
If you’re using a heavy perlite mixture, this can be a bit heavy, which will result in smaller tubers. This is why you should create a combination of growing mediums to attain the best results.
As a rule of thumb, a blend of vermiculite, perlite, and peat will yield a large harvest. The vermiculite and perlite blend will absorb and hold moisture from the nutrient solution. And the perlite will also assist with keeping oxygen at the optimum levels.
While you can place the growing medium for potatoes into literally any container, you will want to ensure that it can accommodate the tubers and media.
Potato tubers cannot be exposed to light for too long as they will spoil. Make sure that the tubers are constantly covered by growing medium.
Before adding the mixed growing medium to the system, you must ensure that your container drains appropriately. If the container allows water to pool, it will affect your crop.
You can also add a layer of drainage chips or LECA (Lightweight Expanded Clay Aggregate) to the bottom to help with drainage and to hold moisture if you forget to turn on the system.
As you might have guessed, potatoes don’t like to be constantly submerged in water. This means you must select a hydroponic system that won’t allow the tubers to be constantly wet.
What hydroponic unit should you select for potatoes?
Selecting Hydroponic Systems for Potatoes
While most beginners will opt for the nutrient film technique or the raft system, these will hamper the growth of the seed potatoes in the long run. For the early stages, the seed potatoes will grow as usual. No issues whatsoever.
Check out our recommendations: Best Hydroponic Systems
But after a few weeks, the seed potatoes will reach their full potential, and the roots will become clogged in the narrow pipes. The potato itself will become very large and depending on your system, you might not be able to remove it.
Also, if you are planning on growing other plants in the system, avoid planting out,
These plants compete with the potatoes and require loads of sunlight, nutrients, and water. It might be tempting to layer your crops above your potatoes, but they need their own space and don’t do well with others.
So, the rule of thumb is to grow them in their own system.
With both ebb and flow and drip irrigation systems, you want to ensure they are put onto a set timer. The watering schedule should be 5-6 times daily at 10 minutes per session.
When selecting a system, the ebb and flow can be operated in a large tub. This can allow your potatoes to reach their full potential depending on your space limitations. You can use as large of a container as you desire and your water pump can handle.
You will be well on your way if the system drains appropriately and maintains the correct moisture levels.
With a drip irrigation system, you can utilize a large tub with drippers positioned in the correct area. But if you are growing your potatoes in a small space, you can use the dripper in 5-gallon buckets.
If you’re unsure whether your system is up to the challenge, do a few cycles without the seed potatoes. Check that your perlite mixture doesn’t dry out completely.
As with any crop, your best tip is to keep an eye on the potatoes. And remember to flush the system to replace the old nutrients.
Now that we know the systems you should use, what are the steps to ensure your potatoes reach their full potential in their hydroponic setup.
Steps For Growing Hydroponic Potatoes
As stated, always start with certified seed potatoes for your hydroponic system. After all, you want to grow a crop void of soil-based diseases.
Once you’ve received your seed potatoes, inspect the spud for eyes (sprouts off the side). You want to see at least two healthy eyes on a spud.
Place the seed potato in Rockwool cubes and keep them moist to ensure they get the best start. Maintain the temperature at around 70°F for 14 days until all the seeds germinate.
Once you’re happy, place your seedlings into the selected system. Make sure that they are covered and that optimum growing conditions are maintained.
Over time the potato seedlings will grow and consume more water and nutrients. Make sure to increase flow rates on your system and stick to the watering schedule.
With the nutrients, don’t overdo it. Otherwise, you might cause the spuds to nutrient block. At the same time, it is always tempting to push your crop to the utter limit — but exercise caution.
And after 120 days in the system, you can harvest your potatoes. You will want to keep a few tubers behind and store them in a cool, dry place, as this will allow you to repeat the entire cycle.
Uncommon Crop For Hydroponic Systems But Worth It
As hydroponic crops go, potatoes are a challenge. Do not attempt it if you’re new to growing food hydroponically.
For those with experience, this can be a highly rewarding crop to grow. It’s also a crop that horticulturists are experimenting with and using to tweak their techniques. So, keeping your eyes peeled for new updates is critical to getting the best return from your system.
So, now you know that it is possible to grow hydroponic potatoes; all that’s left to do is to - well - do it.