Germination is the process of a plant growing from a seed into a seedling according to WVU Extension.
A seed will contain everything that is needed to grow into a plant.
Instead of growing seeds in the soil, you can also grow seeds into seedlings using hydroponics without any soil involved.
One common practice is to use Rockwool to germinate seeds for hydroponics.
But there are other ways that work equally well if not better.
Did you know that it is also possible to germinate seeds for hydroponics without using any Rockwool?
Here is what I think you should know about germinating hydroponic seeds without Rockwool.
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How to Germinate Seeds for Hydroponics Without Rockwool
To germinate seeds for hydroponics without Rockwool you can use jigsaw foam, sand, gravel, vermiculite, peat, perlite, coco coir, hydroton pellets, and rice hulls. You can also mix the materials. After preparing the substrate in a plastic container, check the PH of the growing medium. A pH between 5-6 is optimal for growing seeds. Plant the seeds and add some water, warmth, and humidity.
Use Jigsaw Foam as a Substitute for Rockwool
One of the many alternatives to Rockwool that you use to germinate seeds for hydroponics is jigsaw foam.
This is a material you can easily find in nursery schools or even in children’s playgrounds.
Cut jigsaw foam so that it will support a plant properly.
One good shape to cut this foam into is a pudgy cross.
With this shape, the jigsaw foam will support full plants or seedling plants that are emerging out of a circular opening.
I have often heard people suggest that maybe you can use pool noodles for hydroponics.
Pool noodles are fun to use for general recreation, playing in the water, and training in swimming pools all over the country.
That being said, pool noodles are not necessarily the best choice when choosing a foam item for use in hydroponics.
They can work well for the right plants, though.
You can use a hollow pool noodle in a similar fashion to how you would use jigsaw foam for hydroponics.
It is best to use pool noodles for hydroponics when dealing with larger and longer plants.
I should also mention the fact that sheets of jigsaw foam and pool noodles are created from the material known as ethylene-vinyl acetate.
This compound is utilized in a variety of different items, too.
Some of these items include adhesives, hot glue, baby teethers, and even floats.
One good thing about using EVA is the fact that it is a non-toxic compound.
EVA does not have any chlorides, heavy metals, or BPAs.
I will also add that you do not have to worry about any health concerns from exposure to EVA.
Substitute Rockwool with Vermiculite and Perlite
Before going any further, it is important to point out exactly what vermiculite and perlite are.
Vermiculite and perlite are two light volcanic rocks.
People involved in hydroponics often combine these two rocks because of their complementary properties.
Starting off with perlite, this volcanic rock provides you with a good level of aeration but it does not retain water very well.
Perlite resembles white and small pieces of popcorn. I will also add that perlite is porous but it does not have any odor whatsoever and it is light in weight, too.
Optimally, Perlite has PH levels of between 6 and 7.
Vermiculite complements perlite well primarily because it retains water incredibly well.
Unlike perlite, vermiculite resembles flakes that are light brown or brown in color.
Typically, vermiculite is combined with perlite so that I have a unique growing medium.
As previously stated, the reason that perlite and vermiculite are combined is that they mitigate the downsides of the other material in the mixture.
I recommend this as one alternative to using Rockwool for hydroponics.
Hydroton Pellets Are Another Alternative to Rockwool
Another alternative to Rockwool is hydroton pellets.
You might think why Hydroton pellets?
Aren’t they too big and will leave to big a space in between so seeds will fall through?
You are right.
Whilst hydroton is a great medium to grow plants hydroponically you need to add in some support to germinate and grow seeds.
One solution is to create bedding using a paper sheet that you form so that one end of the paper reaches the bottom of the plastic pot and the other end is used to form a flat bed.
This way the paper will become wet and the bedding that you build with the paper will act as a float where you can put on the seeds.
Over time the roots will grow into the hydroton and the paper towel can be removed gently.
Pellets are also called expanded clay pellets or leca.
Hydroton pellets are pellets made of baked clay and they are available in a variety of different diameters and sizes.
These pellets resemble balls of porous clay.
Please note that these pellets provide a good amount of aeration.
However, I will also add that hydroton pellets will dry out pretty easily, as well.
If I fill an entire grow bed with hydroton, then it will get heavy.
I mention this so that you make sure to use materials in your growing system that can withstand this weight.
The majority of growing techniques work well if I choose hydroton pellets as a growing medium.
Utilize Rice Hulls
First of all, it is important to identify what rice hulls are, exactly.
Rice hulls are the rice milling process’s by-products.
Because they are by-products, one benefit of using rice hulls is that they are quite affordable.
Quite a few developing countries use rice hulls for various purposes.
Rice hulls retain water fairly well and they give me good aeration, as well.
Rice hulls are buoyant. Just keep that in mind and maybe use it to your advantage.
What Containers to use to germinate seedlings
The University of Iowa suggests using clean plastic containers with drainage holes at the bottom to germinate seedlings.
Used containers need to be washed first with soapy water.
Then a bleach solution with a ratio of 1:9, 1 parts bleach, and 9 parts water can be applied to clean the pots entirely.
I for my part usually use a seed tray and fill it with my medium of choice.
As I highlighted in this article this can be Rockwool but there are a lot of alternatives to such as jigsaw foam, perlite, vermiculite, and many more.
Frequently Asked Questions About How to Germinate Seeds for Hydroponics Without Rockwool
Can I germinate seeds using cotton balls?
Cotton balls are one alternative that lets you germinate seeds without Rockwool. You can grow peas, broad beans, mung beans, cress, and more in cotton wool.
Is there a good Rockwool alternative for beginner growers?
Coco coir is a great Rockwool alternative for beginner growers. It is similar to traditional soil and works well for a variety of growing mediums. Coco coir is a processed husk of dry coconut.
Conclusion About How to Germinate Seeds for Hydroponics Without Rockwool
There are quite a few alternatives to Rockwool for germinating seeds for hydroponics.
Which one you choose depends on your experience level as a grower and your budget.
Coco coir is an excellent choice for beginner growers.
However, rice hulls are an affordable choice.
I recommend coco coir simply because it is an easy-to-use growing alternative to Rockwool.
Daniel has been a plant enthusiast for over 20 years. He owns hundreds of houseplants and prepares for the chili growing seasons yearly with great anticipation. His favorite plants are plant species in the Araceae family, such as Monstera, Philodendron, and Anthurium. He also loves gardening and is growing hot peppers, tomatoes, and many more vegetables.