Growing Lettuce Without Soil: Fresh Lettuce All Year Round

Lettuce without soil

Lettuce without soil: how I have fresh lettuce all year round

Why lettuce is the perfect start into hydroponics, which varieties I use and how my cycle of propagation box, propagation station and tower works. You will find the detailed guide with all values on my page Lettuce in hydroponics.

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4 to 6 weeks

in the tower until harvest

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30 to 40 lettuces

on one square metre

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pH 5.8

good range 5.5 to 6.5

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EC to 1.6

I run 1.1 to 1.2 with soft water

Why lettuce without soil works so well

For me lettuce is the plant everyone should start hydroponics with. It germinates quickly, needs little fertiliser and little space, and it shows you straight away whether your values are right. I grow it all year round, outside in summer and indoors under the lamp in winter.

Without soil the roots get water, nutrients and oxygen directly from the nutrient solution. That is why lettuce in the tower is ready to harvest after about 4 to 6 weeks, much faster than in the bed. The daily slug hunt is gone, you have no soil in your home, and no sand sticks to the lettuce. And you hardly need any space: for me 30 to 40 lettuces grow on one square metre, because they stand on top of each other in the tower.

The water runs in a cycle. The pump brings the nutrient solution up, it trickles past the roots and runs back into the container. Lettuce drinks little: for me a full container lasts around 4 weeks.

Lettuce without soil in the HydroFlex Tower from Frankiesgarten — My lettuce in the HydroFlex Tower: no bed, no soil, no slugs.

Which lettuce is suitable?

In short: almost any. You do not need special seeds for hydroponics; completely normal lettuce seeds work. To start with I recommend loose-leaf lettuce, because you harvest leaves from it again and again over weeks.

Variety	How I harvest	Good to know
Loose-leaf lettuce	always the outer leaves	the heart keeps growing, ideal for beginners
Butterhead lettuce	whole, together with the net pot	then the next young plant moves in
Oak leaf and lollo	pick from the outside or whole	colourful mix in the tower
Romaine	whole or pick from the outside	grows upright and needs a little more space

Lettuce combines well with herbs such as basil, parsley or chives in one tower. Large fruiting plants such as tomatoes, cucumbers and peppers, on the other hand, I grow in separate systems, because they need much more space and later a different fertiliser.

My cycle: lettuce all year round

The real trick is not the tower but the supply. I work with three stations that always run at the same time. That way the tower is never empty, and I never have to start from zero again.

1Propagation box: this is where the supply germinates

about 3 days to the seedling · no fertiliser yet

In the propagation box with lid the foam cubes lie as a connected mat. One lettuce seed goes into each cube, two only with weak seeds. Lettuce is a light germinator: I put the seed into the slit and only press it lightly. It likes it cool; 15 to 20 °C is ideal. Above 24 °C lettuce germinates worse, so it does not go on the heater. For me it germinates after about 3 days.

How exactly this works with the cubes, I show you in the post Seedlings in foam cubes. You will find all germination temperatures under Germination temperatures and times.

2Propagation station: this is where the young plant waits

from about 2 cm · EC 0.4 to 0.8

When the seedlings are about 2 cm tall and the first roots are growing out of the bottom of the cube, I put them into a net pot in the propagation station. Once the seed leaves are open, they get fertiliser for the first time, very weak. I increase it slowly as the plant grows. The air bubbler runs there day and night.

For me the propagation station is a kind of holding station. If the tower is full, the young plants simply wait here. Leafy plants could in theory even stay in the station until harvest. But when it gets too crowded and the leaves rub against each other, it is time to move.

3Tower: this is where you harvest

from about 5 cm · EC up to 1.6

From a size of about 5 cm, when the roots are also longer, the lettuce may go into the tower. When a space becomes free there, I always take the largest plant from the station. That way the others get more light and air again. When I eat a lettuce, I fill the space again straight away.

Germinate

15 to 20 °C

Station

from 2 cm

Tower

from 5 cm

Harvest

after 4 to 6 weeks

Better to sow a little more often

If you sow everything at once, everything is ripe at once, and the rest bolts. That is why I prefer to sow small amounts more often. To be honest, I still usually grow more than I can eat. It is completely normal that a lettuce bolts now and then.

You will find every step with all the details, fertiliser amounts and the growing plan to click through on my page Lettuce in hydroponics: from sowing to harvest.

What you need to get started

Lettuce seeds, completely normal seeds
Propagation box with lid and 25 foam cubes or for many plants the Foam mat with 100 cubes
a propagation station, for example for 25 plants or for 35 plants
a hydro tower, for example from my HydroFlex Tower series
a fertiliser for leafy plants, I use Frankie’s liquid nutrient
a meter for EC and pH
indoors in winter a grow lamp

From my shop

Everything for your soil-free start

HydroFlex Tower for indoors and outdoors, seedling box, seedling station, support rings and my own nutrient. After you buy, I’ll help you on WhatsApp.

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Fertiliser, EC and pH briefly explained

Lettuce is undemanding. It stays in the growth phase all its life, because we harvest the leaves. That is why you do not need a bloom fertiliser; I stay with my liquid fertiliser until harvest. During germination there is only water, then I increase the fertiliser in stages.

Stage	EC (mS/cm)
Germination	no fertiliser, only water
seed leaves open	about 0.4
Young plant	about 0.8
Growth in the tower	about 1.2
fully grown	up to 1.6

I have very soft tap water with an EC of about 0.25. I run my fully grown lettuce in the tower at 1.1 to 1.2, and it grows just as well with that. I keep the pH value at 5.8; anything from 5.5 to 6.5 is good. The order is important: always set the EC first, then the pH. The fertiliser changes the pH value.

You can read more about this under EC value, pH value and in the article Lowering the pH value.

My recommendation for getting started

5-in-1 meter for pH, EC, TDS and temperature

Affordable, easy to use and perfectly adequate for beginners.

View on Amazon* ›

* Affiliate link: I earn a commission if you buy. Your price stays the same.

Indoors or outdoors?

Outside in summer

Lettuce grows great outside, even in the rain. But rain dilutes the nutrient solution, so I measure the EC afterwards. Also watch out for shade from trees and houses. In the greenhouse it is usually too warm for lettuce, and then it bolts. In great heat I switch the pump from 5 minutes on and 30 off to 15 minutes on and 15 off. If the leaves droop, water is lacking.

Indoors in winter

At the window lettuce grows without a lamp in spring and summer. In autumn and winter the light is not enough, and the plants become long and thin. Then I hang grow lamps at the side of the tower, 20 to 30 cm from the plants, and let them shine for 14 to 16 hours, never longer. From above only the upper levels get enough light; further down everything stays small.

Lettuce indoors under the grow light in the HydroFlex Tower — Indoors in winter: the lamps hang at the side so that the lower levels also get light.

Mars Hydro VG40 LED grow lamp, pack of 2

I use these lamps myself for lettuce and herbs. At the side of the tower they light up the whole height.

* Affiliate-Link: Bei einem Kauf erhalte ich eine Provision, dein Preis bleibt gleich. Preis inkl. MwSt., zzgl. Versand, Stand 8.11.2026. Bilder: Amazon Creators API

Spider Farmer propagation tent with shelf

Small tent with a shelf on four levels, handy if you start many young plants at the same time.

* Affiliate-Link: Bei einem Kauf erhalte ich eine Provision, dein Preis bleibt gleich. Preis inkl. MwSt., zzgl. Versand, Stand 8.11.2026. Bilder: Amazon Creators API

* Affiliate links (Amazon): if you buy, I receive a commission; your price stays the same.

Harvesting without the tower becoming empty

You harvest loose-leaf lettuce from the outside in. The large outer leaves come off, the heart stays and keeps growing. That way you harvest from the same plant for weeks. A butterhead lettuce you pull out together with the net pot. You throw away the cube, clean the net pot, and the largest young plant from the station moves in.

Frank’s tip: space free, lettuce in a glass

Do you need the space in the tower but not the lettuce yet? Then harvest it anyway and put it with shortened roots in a glass of plain tap water. That way it stays fresh for a day or two.

The most common mistakes at the start

What you see	Usually the cause is	What helps
Seeds don’t germinate	too warm or set too deep	keep cool, only press the seed lightly
long, thin stems	too little light	grow lamp right after germination
Lettuce bolts and turns bitter	too warm or too old	harvest in time, sow small amounts more often
Leaves droop	pump break too long, often in heat	shorten the break
young plants are stunted	too much fertiliser at the start	start weak, increase slowly
brown leaf edges	heat, dry or stagnant air	gentle air movement, lamp not too close

I explain the problems in detail on the lettuce page and in Problems and solutions.

Frequently asked questions about lettuce without soil

Can you grow lettuce without soil?

Yes. In hydroponics the roots grow in water with dissolved nutrients instead of soil. Lettuce is the ideal beginner plant for this, because it grows quickly and needs little fertiliser.

Why is lettuce the best plant for getting started with hydroponics?

Lettuce germinates quickly, needs little fertiliser and space and shows you early on whether your values are right. After about 4 to 6 weeks in the tower you can harvest.

How long does it take until lettuce in the tower is ready to harvest?

After about 4 to 6 weeks in the tower my lettuce is ready to harvest. That is much faster than in soil.

How many lettuces fit on one square metre?

In the tower 30 to 40 lettuces grow on one square metre for me, because the plants stand on top of each other.

Which lettuce varieties are suitable for the hydro tower?

Almost any: loose-leaf lettuce, butterhead, oak leaf, lollo or romaine. To start with, loose-leaf lettuce is the most rewarding, because you harvest leaves again and again over weeks. You do not need special seeds.

Do I need special seeds for hydroponics?

No. Completely normal lettuce seeds work. Seed is seed.

Which plants can I grow in the same tower as lettuce?

Lettuces go well with herbs such as basil, parsley or chives. Large fruiting plants such as tomatoes, cucumbers and peppers I prefer to grow in separate systems.

What is the cycle for lettuce all year round?

New seeds germinate in the propagation box, the young plants wait in the propagation station, and harvesting happens in the tower. When a lettuce has been eaten, the largest plant from the station follows. That way the tower is never empty.

How many lettuce seeds go into one foam cube?

One seed per cube, because each lettuce later grows on its own. Only with weak seeds do you set two.

Is lettuce a light germinator or a dark germinator?

Lettuce is a light germinator. You only put the seed into the slit of the cube and press it lightly; it is not covered.

At what temperature does lettuce germinate best?

Cool, at about 15 to 20 °C. Above 24 °C lettuce germinates worse, with even more warmth often not at all. That is why it does not belong on the heater.

When does lettuce move from the propagation box to the propagation station?

When the seedlings are about 2 cm tall and the first roots are growing out of the bottom of the cube.

From what size may lettuce go into the tower?

From about 5 cm, when the roots are also longer. If the tower is still full, the young plant simply waits in the propagation station.

Why do I not sow lettuce directly in the tower?

In the tower the cube sits deep in the net pot, where hardly any light reaches. Light germinators such as lettuce then germinate poorly or become long and thin. That is why I germinate in the propagation box.

What EC value does lettuce need?

As a seedling about 0.4, as a young plant 0.8, during growth 1.2 and fully grown up to 1.6. With my soft water I run fully grown lettuce at 1.1 to 1.2, and it grows just as well.

Which pH value does lettuce without soil need?

The range from 5.5 to 6.5 is good. I set it to 5.8, and always only after the EC value.

Does lettuce later have to switch to a bloom fertiliser?

No. Lettuce is a leafy plant and stays in the growth phase all its life. I stay with my liquid fertiliser until harvest.

How long does a full container last for lettuce?

Lettuce needs little water. For me a full container lasts around 4 weeks. I top up with ready-mixed nutrient solution instead of constantly changing the water.

How long does the pump run for lettuce?

Indoors 5 minutes on and 30 minutes off. Outside in great heat 15 minutes on and 15 minutes off. If the lettuce leaves droop, the break is too long.

How do I light lettuce indoors in winter?

With a grow lamp at the side of the tower, about 20 to 30 cm from the plants, 14 to 16 hours a day and never longer. From above the lower plants get too little light.

How do I harvest loose-leaf lettuce correctly?

From the outside in: the large outer leaves come off, the heart stays and keeps growing. That way you harvest over weeks.

How do I harvest butterhead lettuce from the tower?

You pull it out together with the net pot. You throw away the cube, clean the net pot, and a new young plant goes in.

What do I do with lettuce if I need the space but do not want to eat it yet?

Harvest it anyway and put it with shortened roots in a glass of plain tap water. That way it stays fresh for a day or two.

Why is my lettuce bolting?

In heat or if it stands too long, lettuce forms a flower stalk and turns bitter. Harvest in time and sow small amounts more often.

Does lettuce grow better in the greenhouse or outside?

In the greenhouse it is usually too warm for it, and then it bolts. Outside it grows great, even in the rain. But rain dilutes the nutrient solution, so you measure the EC afterwards.

Why does my lettuce get long, thin stems?

Usually light is lacking, often at the window in autumn and winter. A grow lamp right after germination keeps the plants compact.

You will find all details with growing plan and seedling card on my page Lettuce in hydroponics. Next up is the hydro tower and the overview Vegetable growing.

Continue with your own growing

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Step by step into hydroponics

168 pages, simply explained for beginners and with videos on the topics (in German). Exactly how I grow myself: from sowing to harvest.

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Which tower suits you?

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