Hydroponic Herb Gardens
Moving Mature Seedlings into Hydroponic Planters


Seeds sprout and quickly grow into robust seedlings when growing in Rockwool Grow Cubes!

Mature seedlings are 2-3" tall with root growing out of the bottom of the cube (usually about 2 weeks after planting - depending on the variety).


When roots grow out the bottom of the grow cube it's time to move them to a hydroponic planter.


What Size Hydroponic Planter?

Unlike orchids or houseplants, the size of the hydro planter for seedlings is not critical for success. 

In fact, planter size is usually determined by how many Grow Cubes you're working with and what's the best fit for your growing area.

Hydroponic Planters come in many sizes

4" Hydro Planter

Perfect for windowsills. Typically holds 2 grow cubes.

5" Hydro Planter

Most popular size. Works well on windowsills. Hold 3-4 grow cubes

7" Hydro Planter

For larger growing areas - typically holds 5-7 cubes.

6", 7" or 9" tall profile Hydro Planters

Floor planters for larger crops. Tall planters come in 6", 7" and 9" sizes



Time for Planting!

For this project we'll be planting an several varieties of lettuce (in the same pot).


Grower Tip: To grow full, healthy looking plants, always use several grow cubes per pot. See chart above. 



1. Soak LECA pebbles for several hours in clear water.  No nutrients yet.


2. Cut plastic cover on grow cube with a scissors and remove it. The plastic cover holds in moisture while seedlings are growing. Won't be needing it anymore.


3. Fill the bottom of the grow pot with pebbles. 


4. Position plant (and Grow Cube) on top of pebbles (plant entire cube - don't try removing plant!). Planting depth for seedlings is important. For a smooth transition new roots should be close to - or in contact with the water when planter is watered to maximum.

Pencil marks maximum water level - that's where Grow Cube will be planted.


5. Holding plants (and cube) in position, add more pebbles. If seedlings are too high - they won't reach the water. Too low and the leaves will be buried. If planting depth isn't right, lay culture pot on its side, slide out grow cubes and start over.

6. When Grow Cubes are in postion, carefully add pebbles to fill in the gaps between the cubes. This can be tricky the first couple of times. Don't worry about damaging seedlings - they're tougher than they look. 


6. Pack down pebbles. Be aggressive so plants are stable in their new pot as they mature. Don't worry about damaging the roots or "squishing" the grow cubes.



7. Insert water gauge and place culture pot in outer pot. Your seedlings might look disheveled at this point. No worries, they'll perk up in a day or two with a little sun.



Watering and Nutrients 

Pour nutrient solution (see below) over pebbles until water gauge reads maximum. When water gauge reads minimum, rewater immediately. Unlike most plants, herbs do not need a dry period between waterings. 

Now, while you go about your busy life, the LECA pebbles will wick the nutrient solution up to the plant gently and evenly. The water gauge tells you when and how much to water. No more guessing!


Water new planter to "Max" on wtaer gauge

Start applying nutrients at full strength immediately. These young plants are hungry!

For best results I use and recommend Dyna-Gro "Grow" 7-9-5 formula 1 tsp. per gallon every watering.



Grower Tip:  Resist the temptation to "top off" the system to keep the reservoir full at all times. Allow enough time between waterings for the water gauge to read empty before rewatering. Roots need air as much as they need water to grow. 



Mature planter 5 weeks later



Why Hydroponics?

How to Grow from Seeds

From Seedlings to Hydro Planters

Tools for Success