7 Easiest Hydroponic Plants to Grow in Under 40 Days 😲

What’s the best thing to grow as a new hydroponic gardener? Confidence.

These easy growing herbs and vegetables will transform you into a hydro hero in 40 days or less. What’s even better is they’ll all grow in ANY hydroponic system you put ‘em in!

General Hydroponics Flora Series - 1 Gal - 3 Pack

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What Makes a Plant “Easy” to Grow?

So…. this ain’t super scientific, but I think I’ve come up with a few good metrics for determining how “easy” a plant is to grow. They are:

pH & EC Tolerance
In order for a plant to be “easy” to grow, it needs to be tolerant of varying pH and nutrient strength levels. Why? Because new gardeners aren’t usually experts at maintaining these levels within tight tolerances.
Light Requirements
With “easy” to grow plants, lights can be “set it and forget it” meaning you adjust the height and intensity of your lights and basically leave them in place FOREVER. This is a lot simpler than constantly adjusting for canopy heights, and mimicking day/night cycles to produce flowers and fruit. You also don’t need super-expensive lights to grow any of these plants.
Time to Maturation
Everything I selected here has a relatively fast maturation. That means you’ll go from seed to feed quickly. You won’t spend weeks wondering if your plants will produce.
Ease of Germination
Everything listed here can be germinated straight from the seed bag. No cold stratifying, or any other crazy shenanigans required. Though I am a believer in pre-soaking seeds prior to germinating. More on that later!
Hydroponic System Requirements
If you’re new to hydroponics, you probably have a pretty simple setup. Maybe a deep water culture, or an ebb and flow system. Perhaps even a nutrient film technique system. Every plant in this list can be grown in ANY hydroponic system. To make things even easier, you can actually grow all these plants together in the same system – at the same time!

The 6 Easiest Hydroponic Plants to Grow

These 6 plants are among the easiest to grow in a hydroponic system:

Lettuce
Spinach
Arugula
Kale
Basil
Cilantro

Like I said earlier, the great thing about this list is you can grow all 6 of these plants together in the same system. How do I know this? I’ve done it!

Tip: If you decide to grow all these plants together, try to keep the nutrient strength within an EC range of 1.0-1.4 so you don’t burn up the arugula. Basil, cilantro, and spinach all have a higher recommended EC range, but they will produce very well at this weaker range. Also, a pH of 6.0 will keep all these plants happy.

1. Lettuce

Lettuce is the long-standing champion of hydroponic gardens. It’s easy to grow, hard to kill, and can be harvested in 30 days or less. Hydroponic lettuce will stand up to wide shifts in both pH and EC levels. Loose-leaf lettuce, such as butter lettuce, allows you to pick individual leaves as needed while the plant continues to grow and produce more leaves.

Germinating lettuce is incredibly easy. The paper towel germination method will have lettuce seeds sprouting in as little as 3 days.

PH level: 5.5-6.5
EC: 1.2
Days to germinate: 3-10 days
Days to Maturity: 3-4 weeks

2. Spinach

Spinach is pretty tough, and will do just fine at lower nutrient strengths when planted alongside other “weaker” leafy greens like lettuce and arugula. Once spinach germinates, it’s game on!

Germination Tip: Soak seeds for an hour before sowing or paper towel germinating. The softening of the seed will speed up the germination process, A LOT!

Grow like a pro with How to Grow Spinach Hydroponically.

PH level: 6.0-7.0
EC: 1.8 – 2.3
Days to germinate: 5-10 days
Days to Maturity: 40-45 days

3. Arugula

If you want a little spice in your life, arugula is the perfect addition to any set of salad greens. Among these 6 plants, it’s the most finicky but don’t let that scare ya’ off. It’s still really easy to grow, and will germinate really fast.

Tip: Keep nutrient strength below an EC of 1.4 to keep arugula happy.

Need some help? Learn more by reading How to Grow Hydroponic Arugula!

PH level: 6.0-7.5
EC: 0.8 to 1.2
Days to germinate: 3-10 days
Days to Maturity: 4 weeks

4. Kale

If you’re a kale fan, you’ll be happy to know you can harvest it in as little as 30 days! Kale is not as light dependent as the other plants in this list, which makes it a great addition to the outer boundary of the grow area. Ya’ know, the area that doesn’t get the most direct light.

Tip: Temperatures under 75°F will keep kale the happiest.

Want to grow healthy kale? Read up on How to Grow Hydroponic Kale!

PH level: 5.5-6.5
EC: 1.2 to 1.5
Days to germinate: 10 days
Days to Maturity: 30-60 days

5. Basil

For as delicate as basil leaves are, it shocks me how easy the plants are to grow. The only thing you need to watch for with basil is early-onset mold or mildew, this will kill ‘em quick. To help prevent this, buy mildew resistant basil seeds and don’t let the seeds get too saturated with water during germination.

Once basil has set its first true leaves, it’s ready to rock n’ roll and will stand up to just about anything.

Tip: Buy seeds that are resistant to downy mildew.

Need more information? How to Grow Hydroponic Basil can help!

PH level: 5.5-6.0
EC: 1.0 to 1.6
Days to germinate: 3-10 days
Days to Maturity: 4 weeks

6. Cilantro

Cilantro is another wonderfully easy to grow plant that germinates quickly and is ready for the first harvest within 40 days. It’s tolerant of a wide range of pH and nutrient strengths. You’re gonna want to keep cilantro trimmed regularly otherwise it’ll get out of control and block light from other plants in the grow area.

Tip: Because it’s quick to bolt in “hot” temperatures, try to keep the growing area below 75° F.

Want to know more? Read How to Grow Hydroponic Cilantro.

PH level: 5.5-6.4
EC: 1.2 to 1.8
Days to germinate: 7-10 days
Days to Maturity: 40-50 days

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Hydroponic Plant Arrangement

If you want your plants to produce at their peak, arrange them in the hydroponic system based on their lighting needs. Among these plants, basil and spinach are the most “light hungry” and will need to be placed directly under the most intense part of the light.

Kale has the lowest lighting needs and can be placed along the boundary of the grow area. I normally keep kale and cilantro in the corners of my grow area.

Lettuce and arugula like a lot of light (but not as much as basil/spinach) and will grow well in the second most intensely lit area of the grow area.

C – Cilantro | L – Lettuce | A – Arugula
K – Kale | S – Spinach | B – Basil

This diagram shows an example grow area, along with plant placement. The yellow rectangle represents the most intensely lit area, directly under the grow light. I’ve placed cilantro in the outer corners only because it can grow pretty tall. You can place it closer to the light, but you’ll want to keep it cut back regularly to prevent other plants from being overly shaded.

This diagram is an example layout, experiment with your system and find what works best for you and your plants.

Hydroponic Plant Nutrients

Your plants are gonna get hungry, luckily all these plants will happily feast on the same kind of nutrient mix. What brand or type you choose is up to you.

All you need is a basic water-soluble or liquid hydroponic nutrient designed to support vegetative growth. If you’re lost when it comes to nutrients, check out Fox Farm Grow Big or General Hydroponics FloraGro. They both work great for leafy greens, & are easy to use.

Great for Leafy Greens

General Hydroponics FloraGro

N-P-K makeup of 2-1-6
Great for vegetative growth

FloraGro is an excellent choice for vegetative growth, and full life-cycle growth of leafy green plants and herbs. Perfect for beginner gardeners.

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Seeds – The Foundation of Success

Want to know my secret to germination success? High-quality seeds.

Seeds are the foundation your plants are grown on. When you’re looking for a house, you don’t want the one with a busted foundation. Selecting plant seed is no different. A lot of “mass-produced” seeds at big box stores are low quality and have really crappy germination rates.

High-quality doesn’t necessarily mean high-priced. Most of the seed I use comes from True Leaf Market. I’ve been really impressed with the quality, germination rates, and price of their seed. Beyond that, they have a huge variety of organic, heirloom, and non-GMO seeds to choose from.

Click this link to get FREE SHIPPING on orders of $35 or more at True Leaf Market.

I earn commissions from qualifying purchases, at no additional cost to you. Also, I only recommend products and companies that I actually use and trust.

Easter Egg – One More Easy Growing Plant

Congratulations! You found the easter egg! Since you made it all the way to the end, I thought I’d share with you one more easy growing hydroponic plant.

Why didn’t I list it above? Because it doesn’t fit the under 40 days model. That’s the only reason. It’s an incredibly easy plant to grow, it just takes a little longer to reach maturation than the others.

How long? 90 to 200 days. To reach full maturity, this plant will need up to 200 days. Don’t worry, you can start harvesting leaves and cuttings from this plant as early as 60-70 days in.

What is it? Oh yeah, sorry about that. It’s oregano!

Oregano is a true honey badger of a plant. It will grow in low light, making it a perfect selection for the perimeter of your indoor garden. As it grows, you can simply route its “viney” tendrils out of the way of your other plants.

Don’t go overboard! One or two oregano plants will produce more than enough oregano unless you’re some kind of crazy oregano fan.
Wanna learn more? Check out this article I wrote on growing hydroponic oregano.

Chris Cook started Happy Hydro Farm to share his passion for hydroponic gardening! Growing your own food is incredibly rewarding both physically and mentally. His mantra - "Take excellent care of your plants, and your plants will take excellent care of you."