How to Start Seeds for Your FlowGrow Tower
There is something pretty special about starting from seed. At first, it does not look like much. A small seed, a damp cube or sponge, and a tray sitting somewhere warm and bright. Then one day, you notice the tiniest bit of green.
With a FlowGrow tower, seeds are started in a germination tray before they move into the tower. This gives seedlings time to develop roots first, so they are stronger and more ready for the change into a hydroponic system.
You are not trying to rush this stage. You are giving your plants the best start.
Seeds do best when they germinate in rockwool cubes or planting sponges before moving into the tower.
Wait until seedlings have visible roots, 2 to 3 true leaves, and stable upright growth.
The simple version: start small, let roots form, then move seedlings into the tower once they are strong enough.
Why start seeds separately?
FlowGrow towers work best with healthy young seedlings rather than seeds placed directly into the tower.
Starting seeds separately gives them time to:
- germinate
- grow their first leaves
- develop roots
- become strong enough to move into the tower
This helps make the first few weeks easier, especially if you are new to hydroponic growing.
What can you start seeds in?
Your FlowGrow Starter Kit includes growing materials designed to support young plants before they move into the tower.
Rockwool cubes
A common seed-starting option for hydroponic growing. Rockwool holds moisture well and gives seedlings a stable place to begin.
Planting sponges
A soft, easy-to-use option for starting seeds and useful when transferring small soil-grown seedlings.
Starting seeds in rockwool cubes
Before planting, soak rockwool cubes in fresh water for around 20 to 30 minutes. This helps them become evenly damp before the seeds go in.
If the seed opening feels too small, gently widen it with the tip of a pencil or something similar. Place the soaked cubes into the germination tray, then add your seeds into the top opening.
Starting seeds in planting sponges
Planting sponges do not usually need soaking in the same way as rockwool, but they should be fully wet before planting.
The goal is damp, not waterlogged. Place the wet sponges into the tray, then add your seeds into the top opening.
How many seeds should you plant?
As a simple home-growing guide:
Leafy greens and herbs
Plant 2 to 3 seeds per cube or sponge. Once seedlings are easier to see, keep the strongest one and gently remove the extras.
Larger fruiting plants
Tomatoes and chillies are usually best with 1 to 2 seeds per cube or sponge because they need more space as they grow.
Thinning extra seedlings gives the healthiest plant more room, light, and airflow.
Keeping seeds damp
After planting, lightly mist or sprinkle the cubes or sponges with water.
You can add a shallow layer of water to the bottom of the tray, around 5 mm, to help keep things moist while seeds germinate.
The cubes or sponges should stay damp, but not heavily waterlogged. Too dry, and seeds may not sprout well. Too wet, and seedlings can struggle.
Do seeds need light?
Seeds usually need warmth and moisture first. Once they sprout, they need light quickly.
As soon as you see seedlings emerging, move the tray into bright natural light. A sunny windowsill, bright indoor space, or suitable grow light can help seedlings grow stronger and less leggy.
Helpful to know: if you use a grow light, place it about 20 cm above the seedlings and follow the instructions supplied with your light.
How long do seedlings take?
Most seedlings are ready to move into the tower within 1 to 3 weeks, depending on the plant type, temperature, moisture, and light.
Some seeds sprout quickly. Others take longer. That is normal.
A lot of the important growth happens underneath, where roots are forming before the plant looks big above the surface.
When are seedlings ready for the tower?
Most seedlings are ready to move into the tower once they have:
- roots visible from the bottom of the cube or sponge
- 2 to 3 true leaves
- stable, upright growth
True leaves are the leaves that appear after the first tiny seed leaves. They usually look more like the mature plant.
If a seedling is still very small, floppy, or has no visible roots, give it a little more time. There is no prize for rushing this part. Stronger seedlings usually handle the move much better.
Moving seedlings into the tower
Using planting sponges
Place the sponge directly into the tower planting opening. Make sure it sits securely and that the base of the sponge can reach the circulating water.
Using rockwool cubes
Place one rockwool cube inside each net pot. Gently press it down so it sits near the base of the pot, then place the net pot into the tower opening.
The sponge or cube should stay in contact with the circulating water so the seedling can continue receiving water and nutrients.
Can you use garden centre seedlings?
Yes, you can also begin with small seedlings purchased from a garden centre. This can be a nice shortcut if you do not want to start everything from seed.
Because garden centre seedlings are usually grown in soil, gently rinse away as much soil as possible from the roots before placing the plant into a planting sponge.
Carefully guide the roots through the centre of the sponge, then place it into the tower.
Helpful to know: rockwool cubes are generally best for starting seeds, while planting sponges are more flexible for transferring small soil-grown seedlings.
Start gently with nutrients
Young seedlings do not need strong feeding straight away.
When seedlings first move into the tower, a gentler nutrient mix helps them settle before moving to stronger feeding.
Seedling nutrient amount
For a 15 L FlowGrow reservoir, use 15 ml Grow A + 15 ml Grow B.
As plants grow stronger, you can move to the leafy greens and herbs feeding strength, or follow the FlowGrow Feeding Guide for your plant stage.
Frequently asked questions
Can I put seeds straight into the tower?
It is better to start seeds separately first. This gives them time to germinate, grow roots, and become stronger before they move into the tower.
Why have my seeds not sprouted?
Seeds may need more time, warmth, or consistent moisture. Check that the cubes or sponges are damp, not dried out or sitting in too much water.
Why are my seedlings long and leggy?
This usually means they are reaching for more light. Move them closer to a bright window or use a suitable grow light.
Why are my seedlings falling over?
Seedlings can become weak if they do not receive enough light or if they stay too wet. Improve light and keep the growing media damp rather than waterlogged.
What are the easiest seeds to start with?
Lettuce, rocket, bok choy, basil, and parsley are often good starting points for home growers.
A simple way to begin
Starting seeds does not need to feel complicated.
Keep them damp, give them light once they sprout, and let them grow strong enough before moving them into the tower.
Once those first roots appear and the seedling is standing on its own, the process starts to feel much easier. And when you finally place that little plant into your tower, it feels like the next step has begun.
Helpful next steps
Once your seedlings are ready, these guides can help you keep growing.
FlowGrow Feeding Guide
Learn how much Grow A and Grow B to use as your plants move through each stage.
Where should it go?
Choose a bright, practical spot for your FlowGrow tower at home.
How long does it take?
Learn what to expect in the first few weeks and when you may start picking.
Ready to start growing?
Start with a few easy seeds, give them light and moisture, and let them build strong roots before moving them into your tower.
