Hydroponics is typically an indoor thing, or at least, that’s the perception.
When we wanted to try growing outside hydroponically, we made some mistakes, but with more research and experience, we learned the truth behind the question: Can hydroponics be grown outside?
Outdoor hydroponics is completely possible. Keeping them outside gives them access to sunlight to help their development. It saves money by removing the cost of lighting. However, too much sunlight may dry the plants out, so pick a spot with a good sun-shade balance to suit your specific plant.
Of course, it’s all a bit more complicated than this, so the rest of the article will cover the details and raise your awareness on how to make the transition to growing your hydroponic plants outside.
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Table of Contents
Can Hydroponics Be Grown Outdoors?
Plants will grow anywhere given the right things.
What are the things they need?
- Light
- Water
- Nutrients
With indoor hydroponics, we provide this through LED grow lights and a hydroponic solution packed with nutrients.
Outside, all of the elements are still provided.
You still provide water and nutrients with the hydroponic solution.
The only difference in growing is you swap out your LED lights for natural sunlight!
Hydroponic plants grow just as well as indoors as long as they’re protected from weather and kept well hydrated.
Some people even believe the sun helps them grow better.
The truth of this claim is a little murky.
Plants convert light energy regardless of whether or not it’s sunlight. It’s about the visible light on the spectrum, not the source.
Grow lights for hydroponics, such as the Mars Hydro, are specially designed to give plants exactly what they need.
So much so that it’s even better than the sun… at least, theoretically.
Outdoor Hydroponics Pros And Cons
If you are considering outdoor hydroponics, there are some distinct pros and cons to consider.
Check out the table for a quick breakdown of this, and read the next section for a few more details.
| Pros | Cons |
|---|---|
| More Room To Spread Out | Battle Pests And Insects |
| The Sun Is A Great Source Of Light | Can’t Control The Temperature |
| More Cross-Pollination | Harsher On The Hydroponic System |
| Less Mess When Changing Water | Wind And Rain May Harm The Plants |
| Lower Cost To Set Up | May Get Dehydrated If Exposed Without A Good Transition |
Pros
More Room To Spread Out
You only have so much space inside, but when you’re outside, there’s a lot more.
Spreading things out makes it feel less crowded.
Plus, it’s good for people to be outside.
The Sun Is A Great Source Of Light
While it’s debated how much better the sun is as a light, there’s no doubt it is exactly what nature intended for your plants.
Packed with light on the exact right spectrum, you won’t have to worry about timing the lights or providing a heater.
The sun will take care of it all for you.
More Cross-Pollination
Some plants, like flowers and fruits, thrive and require cross-pollination.
With indoor hydroponics, you have to take some extra steps to simulate nature, such as using a fan or artificial bee.
When you keep your plants outside, nature will take care of that with wind and bees and even hummingbirds in some cases.
Less Mess When Changing Water
I’m a messy person. No matter how careful I am, I always end up spilling some water when I go to change it.
When I’m outside, I don’t have to worry about that!
If it spills, who cares? The nutrients help the ground underneath it.
It’s easier too, as you just need to bring your hose and bucket of nutrients right to the plants.
Lower Cost To Set Up
One of the bigger complaints about hydroponics is the cost upfront.
Of course, hydroponics is worth it (click the link to see our reasons why), but if you want a little lower cost, you’ll save money by removing the need for grow lights.
Cons
Battle Pests And Insects
When your plants are outside, they can fall to the mercy of the critters out there.
Birds, squirrels, rabbits usually won’t mess with hydroponic plants too much; there’s not enough room for them to climb or land on it.
Insects and other buggy pests, on the other hand, are a large potential problem.
Pesticides will help, as will covering the plants.
Can’t Control The Temperature
When you’re inside, the plants can be at the perfect temperature for growth the whole time.
Outside, you’re at the mercy of the weather.
If you’re in a warm or mild zone, this isn’t as big of a deal.
But if you’re in the north, like us over here in Michigan, this means we lose a good chunk of our growing time due to the cold temperatures.
Harsher On The Hydroponic System
Your hydroponic growing system itself won’t last as long outside.
This is probably the biggest downside of outdoor growing.
The wind, sun, rain, and temperature changes are much harsher on your growing container and hydroponic reservoir than the controlled indoor environment.
A good quality system (see our picks later on!) will still last years, but it will never last as long as an indoor one.
Wind And Rain May Harm The Plants
This same wind and rain will hurt the plants outside if it gets too harsh.
Hydroponic plants don’t have as sturdy of roots.
They trade thick stable roots for thinner roots, all the better to absorb a lot of nutrients for faster growth.
This does mean they are more susceptible to damage from wind and rain, though.
Learn more about how hydroponic roots grow.
May Get Dehydrated If Exposed Without A Good Transition
The sun provides heat and light, which sounds like a good thing, but this combination often pulls moisture out of things.
Hydroponic plants need water more than anything, and dehydration is a severe danger to any roots, especially the thinner ones we see on hydroponic plants.
Outdoor Hydroponics In Hot Weather
Hot weather (more than 80° degrees Fahrenheit) will affect the hydroponic plants and may stunt their growth. The heat dries up the water, dehydrates the roots, raises the EC, and messes with the oxygen levels in the water. Take care when it’s this hot to give it shade and add airflow.
Some plants will thrive in hot weather, but others will shrivel and die.
Research which plants you have and what they can handle.
Take care to test the EC or lower it preemptively by adding fresh, untreated water.
The EC (electrical conductivity) refers to the way in which roots absorb nutrients.
If it’s too high (caused by higher salt content and build-up in nutrients), the roots will become nutrient-locked and not absorb any more.
It’ll starve while it drinks the water.
Shade and airflow are also critical in helping mitigate the heat’s effects.
Use a big cloth shade over the plants during the hottest hours of the day.
When it’s hot, make sure you check the water once per day, maybe even twice per day.
The heat will evaporate the water, raising the EC and hurting the roots.
If it’s really bad, consider getting a water cooler to keep your hydroponic reservoir at a mild temp and not evaporating.
Outdoor Hydroponics And Rain
Rain mixes well with hydroponic plants as long as it isn’t too much. If the rainwater gets into the hydroponic solution, it could dilute the nutrients and make the water less healthy for the plants. Too much aggressive rain and wind will damage the plants just like any other plant.
If there’s heavy rain and it gets into your hydroponic reservoir, empty it out and replace it with a fresh solution.
Can You Grow Hydroponics In Sunlight?
Hydroponics grow well in sunlight as long as the roots don’t get dehydrated. If you’re transferring an indoor plant to the outside, let it build resistance to direct sunlight by keeping out of direct sunlight and limiting the time it’s outside. Follow the specific plants’ normal sun recommendations.
Hydroponic plants, especially ones kept all the time outdoors, respond to the sun just like they would as soil-grown plants.
So really, sunlight is only an issue if it’s normally an issue for the plants.
Use this table for figuring out some common greens and their sun requirements:
| Shade Tolerant | Sun Tolerant |
|---|---|
| Cabbage | Okra |
| Chard | Green beans |
| Peas | Peppers |
| Spinach | Cucumbers |
| Watercress | Tarragon |
| Lemon balm | Dill |
| Catnip | Lavender |
| Mint | Chives |
| Parsley | Stevia |
Outdoor Hydroponics In Winter
If your area gets lower than 40° degrees Fahrenheit outside, it may not be ideal for outdoor hydroponics during the winter. Hydroponic plants will only fare as well as they normally would in winter. If the temp dips below freezing, your plant will die as the water freezes.
If you grow plants outside, bring them in as the temperature gets lower, or consider building a greenhouse and keeping it at a mild temperature year-round.
Best Hydroponic System For Outside
Ebb and flow, top feeding, and aeroponics tend to work best for hydroponic plants outside. These systems keep the water flowing, prevent it from being contaminated, and are generally resistant the outdoor weather.
Hydroponic kits tend to be more expensive than their indoor counterparts, but if you want them to last a long time outside, you need to spend the extra money.
Here are a few options we like:
- Vivosun Hydroponics Ebb And Flow – This is an affordable option and made up of mostly a PVC-pipe-like material.
- Aerospring Vertical Outdoor Hydroponic System – A bit more expensive, but it’s vertical to save space. It’s perfect for the deck or patio with limited outdoor space.
Good Plants For Growing Outside
Great hydroponic plants for growing outside need to be a bit hardier than most plants. They won’t have the thick roots to support the wind. Great plants include:
- Lettuce
- Spinach
- Strawberries
- Bell Peppers
- Herbs
- Tomatoes
- Berries
- Aloe Vera
5 Tips For Growing Hydroponics
When growing hydroponics in the outdoors, there are general tips to follow to help you get a great plant yield every time.
Plant Them In The Sun
Don’t make the same mistake I’ve made; make sure you get your plants somewhere they get at least 6 hours of sunlight.
8-10 hours would be better, if possible.
Fortunately, my wife is the one with the green thumb, and she’ll often come behind me to fix my planting mistakes.
Keep in mind the changing seasons too.
If you live in the northern hemisphere, the sun stays lower toward the south as the colder months approach.
There will be fewer hours of sunlight too.
The southern hemisphere is the opposite.
Keep all of this in mind when you pick a spot.
But one of the great things about hydroponics is that they’re easy to move, so just move it on over if you notice a problem.
Keep The Water Cooler
Keep the water cooler than the air outside in most cases.
A slightly lower temperature for the water will actually help increase hydration and nutrient absorption.
The best temperatures are between 65-75° degrees Fahrenheit (18-24° C).
Keep the reservoir in the shade where possible and cover it up to block the sun.
You should be doing this anyway as sunlight encourages bacteria and mold growth in water, which is bad for the roots.
If needed, use an air conditioning unit for water to keep it cool.
Track The Electrical Conductivity
Keep an eye on the EC of the water.
When it gets too high, it’ll stop the plant from absorbing nutrients.
The best EC is from a range of 0.5 to 2 mS/cm.
When it gets too high, add more fresh and untreated water to lower it again.
I like the BlueLab Pen Tester for water to track this.
It costs a bit more, but it’s accurate, easy to use, and lasts a long time.
Allow For Air Flow
Don’t place your hydroponic plants in a place where the airflow is blocked off.
They do well with some airflow to keep the air temp regulated and help with cross-pollination.
If you live in a windy area, it’s OK to give it some protection, but it needs some air motion.
Protect From Pests
Bugs are going to be a problem with outdoor plants; accept that.
If you’re averse to pesticides (and I don’t blame you), try more natural options like spraying with white vinegar and lemon juice or sprinkling cinnamon around.
It may not work quite as well, but it’s a lot safer and more organic.