Following on from last issue’s introduction to taking cuttings, Everest further explores the practicalities behind taking cuttings and also looks at some alternative propagation techniques.

Plants are totally amazing things.  Imagine if you could chop one of your fingers off, dip it in some hormones, and grow another whole “you”?  The mind boggles.

Let’s get started with some practicalities…

Starting from scratch

If you’re starting from scratch then you’re starting from seed.  Once you’ve germinated your seeds the first thing you need to do is to label each seedling.  I usually combine an acronym representing the plant variety with a number.  So for instance, if I germinate ten White Wonder tomato seeds, I would label each seedling WW1, WW2, … WW10, etc using plastic plant labels and a permanent marker pen.  (This saves you writing on the pot which might cause confusion should you re-use the pot for future crops).

Now each of your plants has its own name!  Charming!  But this isn’t just a sentimentality – it’s important because even seeds from the same packet can express themselves in vastly different ways so keeping individual track of them all is crucial.

I grow my seedlings under 18 hours of light a day.  After three or four weeks, or when they have four or five internodes (the space on the stem between branches), I lop off the top of the plant and take it as a cutting – making sure to give it the same label so I know where it’s come from!  Sometimes I’ll take two or three cuttings from a seedling if it is big enough.  Cuttings taken from side shoots have exactly the same genetic qualities as cuttings taken from the main stem.

Growers are divided over the next stage.  You can either flower off the original seedling (by increasing the length of the night period to twelve hours or more) to determine its sex, or you can wait for the respective clone to root, keep the seedling in a vegetative state (in a separate growing area), and flower off its clone instead – this is called ‘cloning for sex’.  The aim of both games is to determine the sex of the seedling whilst retaining its genetics for possible future use.  With all these seedlings and cuttings flying about, you’ll be pleased you established a rigorously scientific labelling scheme!  For instance, many growers like to retain only female plants – so as soon as they discover that a particular seedling is male, they remove it from their grow-room, and remove any cuttings taken from it too!

Hopefully you reach your final goal – you’ve established the sex of all your seedlings, flowered off the ones you wish to keep, spotted the clear winner (i.e. the plant which produces the highest quantity and quality yield) and then referred back to your vegetative room to find a 100% genetic copy of that winner.  Now you can establish that as your mother plant and fill your grow-room with winner after winner after winner!  Oh glorious clones!

You don’t have to take cuttings from a plant in a vegetative state – you can take a cutting from a plant well into flowering and revert it back to vegetative growth by placing it in an 18/6 or 24 hour light environment.  However, cuttings taken from plants in flower will take longer to root and have a lower success rate than those taken from plants in vegetative growth so I wouldn’t recommend it outside of emergencies!

When I take a cutting I have found that it behaves as if it were a new plant (but it is still technically as ‘old’ as the mother plant) – as far as I know there is no degradation of the genetic material and no change in the plant’s qualities.  So a clone taken from a clone taken from a clone, etc, is still exactly the same as the original.  Some friends of mine have reported that strains become ‘tired’ through repeated cloning but I’ve had no first hand experience of this.  If any readers beg to differ then please get in touch.

If you are not careful a mother can become affected by viruses from dirty scalpels or pests such as whitefly and spider mites, which might explain the “tired“ strains. To get a clean mother take a small cutting from the end of a branch while the mother is growing vigorously. Then grow the cutting as fast as possible into a large plant and take cuttings as quickly as possible. Use this new cutting for your new mother. The growing points grow away from the viruses. Leaving a mother to stagnate allows these viruses to affect every part.

Remember, when taking cuttings, it’s really important that you sterilise all your tools before you start.  Fresh cuttings are easy targets for viruses, fungus, and diseases during their pre-rooting incubation period. Wash your hands in alcohol, and also use it to clean out any receptacles you are using (eg. For rooting hormone) – also use it to clean your scalpel or razor blade.

So let’s take a look at some different cloning techniques.  Last  time I mentioned that my favoured technique was using rockwool cubes. This is because they are pre-formed, hold the cuttings sturdily, and are fairly easy to work with.  But you can just as easily take a plastic cup and fill it with soil, perlite, or coconut fibre and use that instead.  The trick is not to let the medium dry out and to maintain high humidity levels.  There are lots of different ways of achieving this ‘incubation environment’ – here are just a few:

Cloning in water

Easiest of them all!  Fill a glass with some water (preferably distilled or high quality water) and drop three or four cuttings in!  Just like your missus does when you buy her some flowers!  (I sense some of you have blank looks on your faces)  No humidity dome or covers required!  Just make sure there are no drafts.  Place in diffused sunlight or under fluorescents.  For the highest success rate, remove any larger leaves, and change the water daily or aerate it.  Try adding a high P dilute nutrient solution over the coming days.  Finally, if you are using water from the tap, let it sit for a day or so to let the chlorine evaporate.

Cloning in bubbles!

Bubble propagators work by pumping air into water or a dilute nutrient solution and placing cuttings in small net pots (with a little substrate to keep them stable) so that the cutting is sitting just in the water below. The net pot should sit a little above the water.

It’s a simple and efficient system. If performed correctly its possible to achieve 100% rooting success without any stop to growth. In effect, the bubbles surround the cuttings, creating air that is close to 100% humidity just above them. A lid is totally unnecessary if there are no strong draughts. Because humid fresh air is coming up around the cutting constantly the leaves lose very little water. Without a lid the CO2 and oxygen stay at ideal levels and light is not reflected or absorbed and lost.

One commercially-available version of this propagator is called The Cutting Board, made by GHE. If you want to make your own it is quite easy … in a Blue Peter way.

Equipment:

• 1 deep plastic tray. At least 8 cm deep to allow enough room under the net pots to allow the roots to develop.
• 4cm net pots
• Clay pebbles or Diahydro to fill the pots.
• Corriboard to cover the tray.
• Air pump, 320 litres per hour is enough for a small tray.
• Air line
• Air curtain

Carefully cut circular holes in the corriboard to fit the net pots. Fill the tray with a dilute nutrient solution such as Formulex or Bio Heaven and adjust to a pH of 6.5 if necessary. Arrange an air curtain along the bottom of the tray so that as much of the water is moved by the bubbles as possible. Cuttings along the edge of the tray may be slower as they are in a more stagnant area, as much air curtain as possible should be fitted in the tray. Poke the cut end of the stem through the net pot then fill the net pot with clay pebbles or Diahydro.

Some cheapskates just poke the cuttings through holes in the corriboard and keep them in place with a plug of rockwool. The only problem with this method is that it is difficult to remove the cutting without breaking the roots.

Lift the corriboard every day to inspect the roots and check that the air curtain is still bubbling well. The water level may go down quickly in dry conditions and plain water should be added. Change the entire nutrient solution every five days. If the bubbles slow down take the air curtain out and massage it vigorously under water until it froths again. Long healthy roots should have developed within ten days, if you leave them too long they can tangle up with other roots and may get damaged when removing the cuttings to transplant them. They will also often get damaged when transplanted to their new medium. It is best to transplant the cuttings when the roots are an inch or so long to avoid snapping them. Do not remove the cuttings from the net pots they have been raised in, plant the whole thing in their new home. Cuttings raised by this method can be used in any system.

The equipment must be cleaned and sterilised between each crop of cuttings. Simply scrub out the tray and net pots and wash with Liquid Oxygen. It is best to use new clay pebbles or Diahydro with each new set of cuttings.

If you see any sick roots or rotting cuttings take them out immediately before other cuttings are infected. In organic systems add some fungi such as Advanced Nutrients’ Piranha or Trichoderma from Canna or GHE. With non-organic feeds you can add five millilitres per litre of Liquid Oxygen. To prevent the large quantities of air passing through the propagator carrying disease spores onto the cuttings it is best to purify the air in the propagation area with an ioniser or HEPA filter.

Cloning in air

Amazingly, you don’t need a solid rooting medium to propagate your cuttings.  An aeroponic propagator simply supports your cuttings leaving the lower portion to root in a fine mist of nutrients!  This gives the roots access to nutrients and water whilst maintaining very high oxygen levels – this is great for root health!

Now, I only want to touch on aeroponic propagation because I’ll be introducing the whole science of aeroponics in more detail in our next issue with the help of the aeroexperts at Aeroculture.  These guys have forgotten more about aeroponics than I know.

Until then, goodbye my friends, and happy cloning!