If you’re wondering how to start hydroponic seeds, you’ve come to the right place. It’s best to start hydroponic plants from seeds because you have complete control over how the seedlings grow up and can fully optimize their solution of nutrients, light, temperature, and more. Hydroponic seeds may take some trial and error, but they’re worth it in the end.

Let’s discuss how to start hydroponic seeds and answer all your burning questions!

Why Should You Start Your Hydroponics From Seed? Benefits

One of the main benefits of starting your hydroponics from seed is that you’re fully in control of plant growth. In addition, there’s no chance that pesticides were used on your seedlings.

You also have more varieties of seeds to choose from, compared to a limited selection at your local nursery.

You can treat your seeds correctly. When you’re sure that your seeds have had the right amount of water, fertilizer, and light, they will adapt better to your hydroponic system. If you buy seedlings, they may not have had the right conditions when growing up.

When you start your seeds hydroponically, you don’t need to rinse any soil off of their roots, which can damage them. There’s also no risk of soil-borne diseases.

Lastly, you’ll save a pretty penny. Seed packets are much more cost effective and you can potentially grow dozens or hundreds of plants for the cost of one pack from the nursery.

What do you Need for Hydroponic Seedling?

Now let’s discuss everything you need for hydroponic seedlings, including starting medium, heating mat, grow lights, nutrient solution, and more!

Starting medium

There are plenty of different starting mediums to choose from.

Coco coir. Coco coir is made out of strands of coconut husk. It’s sustainable and can be bought organic. It retains water really well so you don’t have to worry too much about over- or under-watering. It’s also anti-fungal so you don’t need to use as many chemicals!

Rockwool cubes. Rockwool cubes are great in an enclosed starter system that has airflow around the plant roots.

Rockwool cubes have pre-drilled holes so that the plant roots can pop through and have enough room to develop before transplanting. They also have great drainage to avoid root rot.

Starter plugs. Starter plugs don’t provide as much room for roots as rockwool cubes do, but they’re still highly effective. Starter plugs come sterile and don’t need to be soaked in water. Get starter plugs that are pH neutral if possible.

Starter plugs that don’t have any nutrients will have a higher pH range because seedlings absorb extra fertilizer in their beginning stages.

Heating Mat

Heating mats provide moisture and warmth throughout the germination process. They help battle the cold temperature of your air conditioner and make sure your germinating seeds are warm enough! 

Grow Lights 

Grow lights are vital to plant growth. There are a few different kinds of grow lights to choose from:

HID grow lights have a large spectrum range. HID grow lights are great if you’re germinating your plants in the vegetative state.

LED lighting is energy efficient and doesn’t give off as much heat as other types of grow lights. LEDs are a great choice if you’re looking to flower your plants.

Fluorescent lighting is inexpensive, but less effective than HID and LED lights. However fluorescent lights don’t emit enough blue light.

CFLs are cheap and emit plenty of red and green light. They’re good for starting seeds but your plants will eventually outgrow them.

Nutrient Solution

If you’re a beginner grower, it’s a good idea to start with a pre-mixed hydroponic nutrient solution. Look up the recommended NPK for the plant you’re growing and start from there!

Measure your solution’s EC with an electrical conductivity meter. This detects how the total level of dissolved nutrients in your system.

Monitor you EC daily. As your plants uptake nutrients, the EC will drop and that lets you know that it’s time to add more nutrient solution.

Ziploc Bags, Containers, or Railways

Search for containers with a depth between 4 and 6 inches so that your seeds have plenty of room to grow roots.

Chemicals for raising or lowering pH levels

It’s important to adjust your pH to ensure proper uptake of nutrients.

If you’re starting your seeds in an environment that has a high pH, add an acid like nitric acid or phosphoric acid to balance it out.

Just be careful not to add so much as to create a buildup of salts, so only apply what you absolutely need.

Steps for Starting Hydroponics from seeds.

farmer talking about hydroponic seeds

Planting The Seeds

You can choose two ways to plant your seeds: either buy cubes that already have holes in them, or make the hole yourself (no more than 1/4 inch deep).

Put a few seeds in each hole. Apply very little pressure, just enough to push the seed down into the hole. Then add another bit of rockwool over the seed to cover it.

Next, cover the container to mimic a dark environment. This will tell the seeds to germinate.

Adding Water

It’s important to check your water level every single day, especially when just starting out.

Use 1/4 strength nutrients while your hydroponic seeds are germinating and 1/2 strength nutrients when they’re seedlings.


If you’re using a window as a light source, rotate the trays once every day or so to avoid your seedlings from leaning in one direction towards the light.

Three hours of sunlight or five hours of artificial light are sufficient for germination. Larger plants can require up to 15 hours of light a day! At that point, a window will no longer work.

Seedlings also need time in darkness, so make sure there aren’t any household lights on near them during their dark period.

Lastly, position your grow lights high enough so as not to scorch your seedlings. As they grow, you’ll have to raise your lights higher and higher. 


Seeds take anywhere from a few days to three weeks before they can be planted into your hydroponic setup. If you want to transplant a little sooner, you can move them over once roots start to appear. 

Be very careful when transplanting your seedlings. This is their most vulnerable stage, and they may go through shock at first from being put into a new environment. If they don’t look happy at first, give it a day or two before becoming concerned.

Hydroponic seed germination do’s and don’ts

DO use heat mats for germination.

DON’T use heat mats for growing.

DO provide enough aeration.

DON’T place by a drafty window.

DO water your seeds enough.

DON’T over-water them to the point of excess moisture.

DO realize that it’s hard to germinate seeds.

DON’T give up if it doesn’t work your first go-around!

Phases of Hydroponic seed germination

Phases of hydroponic seed germination include:

1. Planting

2. Germination

3. Sprouts

4. Transplanting

5. Adult plants!

How long does it take hydroponic seeds to germinate?

It takes hydroponic seeds anywhere from a few days to a few weeks to germinate, depending on what plant you’re growing and how ideal the environment is.


Now it’s time to answer some frequently asked questions about how to germinate hydroponic seeds.

Can You start seeds directly in hydroponics?

While you can start seeds directly in hydroponics, it’s typically recommended to start your seeds separate from your hydroponic unit and then transfer the seedlings. This article will explain exactly how to do that!

How do you germinate hydroponic seeds without Rockwool?

You don’t need rockwool to germinate hydroponic seeds. You can choose from any other growing medium such as coco coir, perlite, peat, and more. You can mix mediums to create the most ideal conditions.

Do hydroponic seeds need light to germinate?

Some hydroponic seeds need light to germinate and others don’t. It all depends on how they germinate in the wild.

Some plants naturally drop their seeds and they germinate on the soil where they’ve landed without being buried. Other plants need their seeds to be placed underground by an animal before they’ll germinate.

Can you use any seeds for hydroponics?

You can use any seeds for hydroponics, but it’s best to get organic seeds from a reputable source.

How to germinate seeds for hydroponics with Rockwool

To germinate hydroponic seeds with rockwool, simply plant a few seeds per rockwool cube and put them by a window to germinate. Rotate the tray so the seedlings don’t bend one way towards the light. When the seedlings are a few inches tall, it’s time to transplant them into your hydroponic setup.

Hydroponic seed starting mediums

Hydroponic seed starting mediums include Rockwool, perlite, coco coir, starter cubes, and more, each of which has its own benefits and benefits.


There’s surprisingly a lot to know about how to start hydroponic seeds! But now that you’re armed with this information, you can start your own seeds in no time. There’s also something incredibly rewarding about starting from seed and seeing your plants grow up into mature plants through all their stages of life.

Read through the rest of our blog for more hydroponic gardening tips!