Propagation is simply the creation of new plants. Many growers propagate hydroponically to benefit from early rooting and faster growth rates. This is possible because hydroponic media provides the root zone with easy access to water, nutrients, and oxygen.

Propagation: seed vs. cuttings
Firstly, as with any type of propagation, you need to decide whether you want to grow from seed or from cuttings. Generally, growers who propagate from seed do so because it gives them peace of mind that their plants will be disease and pest free. However, the main draw back with this method is that the characteristics of plants you produce can be inconsistent. Whereas, with cuttings it’s much easier to produce plants that are identical to their healthy parent. Other advantages of cuttings include:

• earlier flowering
• improved plant stock
• plant species which are more adaptable to climatic variations

Also, if you use your own cuttings, it’s still easy to create insect and disease resistant plants. However, for your first gardening venture, you’ll probably have to start growing from seed. This is fine so long as you only plan to grow a single crop. You’ll need to germinate any seed you plan to use. It’s advisable to germinate several seeds at the same time. You’ll then be able to choose a mother (stock) plant from which you can take cuttings in the future.

• 1. Rockwool propagation cubes / Fleximix plugs.
• 2. Rooting hormone, such as Gel 4 Plugs.
• 3. Heated propagator / unheated propagator, such as the Stewart Propagators.
• 4. Fluorescent lighting, such as the Visi Lux lighting unit.
• 5. Sterile scalpel.
• 6. Spray bottle.
• 7. Vegetative nutrient, such as Vita Link Grow.
• 8. Rooting stimulator, such as Vita Link Bio-Plus.
• 9. Perlite and / or vermiculite.

This article explains how to propagate using rockwool cubes. However, the process is basically the same for all types of propagation, such as FlexiMix plugs.

The Mother/Stock plant:
You’ll have to grow your seedlings under 18 hours of light until they are suitable to take cuttings from. This is usually when they are between 12-18 inches or have 8-10 internodes. Always give your cuttings the same mark as the mark you have given the plant you took them from. You should then give your seedlings 12 hours of light and 12 hours of dark to determine which shows favorable characteristics (i.e. quickest to root and/or best flower development). However, your cuttings will need 18 hours of light and 6 hours of dark. The cutting with the same mark as the seed with the most favorable characteristics should be taken as the Mother Plant.

Quality of cuttings:
The hormone content of a cutting determines its quality. If you want strong healthy plants, it’s important to consider quality. The highest concentration of growth is concentrated at the base of the plant around the inner shoots. This is where you should take your cuttings from. Growers often refer to this section of the plant as the zone of juvenility. Without stripping more than 25% of the foliage, take as many cuttings from the mother plant as possible. Also, it’s preferable to use cuttings which have a few leaves. Cuttings with large leaves tend to be unable to absorb sufficient water through their stem. Those with thinner stems will also root much faster than cuttings with fatter stems.

Fluorescent lighting:
As stated above, seedlings/mothers need to be grown under 18 hours of fluorescent light and 6 hours dark. However, once they are well rooted, you’ll need to switch to 12 hours of HID light and 12 hours of dark to initiate flowering/fruiting. In the first week, before the roots have formed, cuttings will perform best with the Visi-Lux lighting unit positioned 4cm away from the propagator lid. Alternatively, you can use 55 watt compact fluorescents 30cm away. You should never use HID lights for propagation as they emit a lot of light intensity and heat.

Rockwool propagation cubes:
As highlighted above, the main advantage of rockwool is that it holds more air and water than any other growing medium. Rockwool is also inert and sterile and doesn’t hold on to nutrient in any way. The roots are clearly visible and it’s very easy to tell whether the cubes are moist or dry. Transplant into larger rockwool blocks or any other hydroponic media with the minimum of fuss. Cuttings should take approximately 4-10 days to root. At this stage, you’ll need to transfer your cuttings into larger rockwool cubes and then into pots containing granulated rockwool.

A simple step by step guide to taking cuttings:
1. Clean all work surfaces and equipment with a disinfectant, such as Room Clean.
2. Mix an equal amount of perlite and vermiculite together.
3. Place perlite and vermiculite in the propagator to a depth of 1 inch.
4. Soak the rockwool cubes in the nutrient solution (half strength). Gently pinch the cubes to remove excess liquid. Plants need oxygen to root; rockwool that is too wet can prevent rooting and encourage disease.
5. As highlighted above, you should take cuttings from the base of the plant, around the outer shoots. Choose shoots with 3-4 sets of leaves. With a smooth motion, cut at a 45 degree angle, just below the internode (branch/stem joins).
6. Immediately immerse the cut stems into a bowl of lukewarm water.
7. Remove the bottom leaves from the stem. Also, if the cutting has more than one large fan leaf, remove the extra.
8. With the scalpel, gently scrape the lower part of the stem. This will help initiate faster rooting.
9. Squirt the rooting hormone into the cube.
10. Gently insert the cutting into the cube. Lightly pinch the cube to hold the cutting in place.
11. After all the cuttings are inserted into the cubes, place them on the perlite/vermiculite bed. Lightly push the cuttings into the bed to ensure that they have a consistent and evenly moist environment.
12. Finely mist the cuttings with water, and then place the propagator lid on the tray.
13. Place the Visi-Lux or fluorescent lights over the propagator. After 48-72 hours, open the vents of the propagator slightly. Too much humidity and not enough air flow can cause fungal disease (also known as ‘Damping Off’ disease).
14. Give your cuttings 18 hours of light a day. However, if the air temperature is cold, leave the lights on for 24 hours a day.
15. Once a day remove the propagator lid and finely mist the propagator lid.
16. Roots should appear within 4-10 days. Once this is evident, the propagator vents can be opened.
17. If you wish to transplant the propagation cubes into larger rockwool blocks, simply pre-soak the blocks with a vegetative nutrient (half strength), and again add the rooting stimulator.
18. As with the cubes, it’s important that the rockwool blocks are not too wet. Insert the cubes into the larger blocks and place them back on to the perlite/vermiculite bed. If the cubes start to dry before any roots start to emerge, moisten with pH adjusted water.
19. Roots should appear within 2-7 days. Once this happens, you can plant your roots into your chosen hydroponic system.


Author: Steve

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