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how to germinate seeds with rockwool

How to Grow Lettuce from Seed in Rockwool

In this tutorial we are going to learn how to grow lettuce (type: May Queen) from seed in the rockwool as growing medium. The process is easy and straight forward.

Equipment need

Before we start we have to make sure that we are having all necessary parts for growing lettuce. The parts that we need are:
– A pack of May Queen Lettuce seeds
– A sheet of rockwool blocks
– A water pH Meter
– A pH Minus solution
– A thermometer that can measure the temperature of the water and the temperature of the air
– A enough large transparent food container with cover

All the things needed in this tutorial you can buy at local garden or hydroponics store. Or if there is none of them around, you can find them on this Amazon list here: http://amzn.to/1TkwktC

Prepare rockwool for planting lettuce

  1. First we take a bowl and that is large enough to have all of our rockwool soaked in water.
  2. Fill 3/4 of bowl with tap water
  3. Take a pH meter and remove the black cap from it.
  4. Place pH meter tip (the point that cap was placed before we removed it) in water and turn the pH meter ON.
  5. Wait few minutes for value to stabilize
  6. If the pH level is higher than 4.0 then add few drops of the pH Down (or pH Minus) liquid to bowl and stir it well and go to 3. point of this step and repeat points 3,4,5 and 6 until you get pH level of the water in bowl to be 4.0
  7. Now you can put cap back to pH meter and turn pH meter off and place it somewhere else
  8. Take the thermometer and check the temperature of the water
  9. If temperature is not in range of 15 to 20 ВєC (59 – 68 ВєF) then heat up or cool down water so it’s temperature is in our desired temperature range
  10. Now we can place our rockwool in the bowl with water
  11. Put it aside for 30 min and then place it on the steep surface so the rockwool can release all unnecessary water.
  12. Leave the rockwool on that surface for 15 min before proceeding to next step.

Make holes in the rockwool

In case that your rockwool is combined with many pieces in one big piece now is the time to split it in those smaller blocks.
1. Take a small stick, wooden or plastic it doesn’t matter, just make sure that it is not more than 2.5mm wide. For example you can use stick for placing small meat pieces on the grill or toothpick.
2. From bottom of the stick measure 6 mm and with the marker or pen write a tin line exactly on 6mm point from the bottom of the stick
3. Take each block of the rockwool and push the stick in it so that you reach that 6mm mark that you’ve previously made. Please take special caution to make sure you don’t push the stick more than 6mm in the rockwool.

Place the seeds in rockwool holes

  1. Takeout the seeds from packaging
  2. Place a single seed in each hole that we’ve previously made in the rockwool.

To make it easier, you can use the stick that we used before and carefuly with the stick push the seed inside the hole. Also make sure that you don’t push the seeds more than 6mm in the rockwool.

You can also put a ice cream stick on the edge of the rockwool and write the date so later when you plant more lettuce you can easily see when are the seeds planted

Place the seeds container near the window

  1. In the transparent food container place all the rockwool blocks so the holes are facing up and close the lid
  2. With thermometer check the temperature in the room, it should be in range of 15 to 20 ВєC (59 – 68 ВєF). In case your room temperature is warmer or colder than accordingly adjust the temperature so it is in between 15 and 20 ВєC (59 – 68 ВєF)
  3. Place the food container near the sunny window

In next 2-4 days we should see small sprouts coming out. During this time please maintain the room temperature in between 15 and 20 ВєC (59 – 68 ВєF), also check the rockwool and see if it’s drying out, and if necessary spray water on it so it get moisture but make sure to not over water the rockwool so when you pull the block of the rockwool up, water should not leak from it.

How to Grow Lettuce from Seed in Rockwool – In this tutorial we are going to learn how to grow lettuce (type: May Queen) from seed in the rockwool as growing medium. T…

Problems Germinating With Rock Wool

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Rock wool, an inorganic material made from sand and basalt rock, is a popular choice for hydroponic seed germination. It holds large amounts of nutrients and water and provides good oxygenation for growing seedlings. This material also comes in a range of shapes and sizes and is relatively easy to work with. Like other germination substrates, however, it has some disadvantages. There are several common problems you may encounter while attempting to germinate in rock wool.

Acid-Alkaline Imbalance

Rock wool naturally has a very high pH, producing an extremely alkaline environment when wet. Most seeds germinate poorly in alkaline conditions and prefer balanced to slightly acid environments. If your seeds have a low germination rate or germinate slowly, you may need to irrigate them with a more acidic nutrient solution to re-balance their growing environment.

Mold Problems

Rock wool easily absorbs water and tends to stay wet for long periods. This makes it an excellent choice for hydroponic systems that are at risk of losing power. The rock wool’s high moisture content prevents plant roots from drying out. This same property can promote fungal growth, encouraging seeds to mold and rot instead of germinating properly. The risk of this problem is highest when the rock wool is completely saturated rather than merely damp. If your seeds develop mold instead of sprouting, try using less nutrient solution in your substrate.

Overpopulation

Rock wool substrates often lead to overcrowded growing conditions. When you sow many seeds in a single rock wool cube or slab, a high germination rate can stunt the resulting seedlings. Thinning, the process of removing extra seedlings from the substrate, is impossible in rock wool because the roots become too integrated with the substrate. Taking out one plant can damage its neighbors. Seed rock wool substrates carefully to prevent too many plants from growing, using only one seed per cube for large plants like the tomato and only two seeds per cube for leafy greens and other small plants.

Poor Airflow

Despite its ability to hold large amounts of water, rock wool usually keeps plants fairly well oxygenated. This occurs because the porous nature of the material creates air pockets even in saturated substrates. If your newly germinated plants show signs of black spots on the leaves, have mushy stems and branches or have black rims along the edges of their leaves, they may be suffering from poor airflow. Correct this problem by reducing the ambient humidity in the hydroponic enclosure and introducing less water to the substrate. Avoid crushing or compressing your rock wool to ensure that it retains enough air pockets.

Problems Germinating With Rock Wool. Rock wool, an inorganic material made from sand and basalt rock, is a popular choice for hydroponic seed germination. It holds large amounts of nutrients and water and provides good oxygenation for growing seedlings. This material also comes in a range of shapes and sizes and is …