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Hibiscus Propagation
 More Information?  Questions?  Email me!ganmor@hotkey.net.au

Hotbed Discussion

These two tubes show roots at 3 weeks with scions starting to take nicely. I used to remove all rootstock eyes but I am experimenting with1 to 2 eyes retained.  Eyes below ground were removed before planting.

The propagation mixture is 3 parts local river sand (finer than I  would prefer but adequate nevertheless), 1 part perlite and 1 part peat.

I've used an all perlite mix in the past, also a 4:1 perlite : vermiculite and a 5:1 perlite : peat.  They all work fine as they DON'T STAY WET!

Note: I have retired fully from propagation now and this facility is no more - but the details are here for your information.

The bench thermostat is set at 32o Celsius, (90o F) turn off, 27o C (81o  F) come back on.  The bed is heated electrically with 2.5 mm2. V90 rated wiring (means the insulation can withstand up to 90o C) connected to a 32v transformer (similar to that of an arc welder).  I tried to heat a 9 m2 bed previously but it was too much in a 3 inch (75mm) deep bed.  Hence this time I re-wired it as 2 parallel 4.5 m2 beds.  Next time I would use 6 to 6.5 m2 beds for more efficient use of the heat.

I have used plastic trellis mesh in 5 cm squares to make a wiring "mat" which just rolls out onto the bed - very useful if I wanted it relocatable.  It would probably be more efficient to wire the 130m of wire at 5 cm spacings but I doubled it and wired the 65 m of doubled wire at 10 cm spacings on the plastic grid and then laid it upside down to give a degree of protection to the cable from objects that might get poked into the bench from time to time.  (In the 4.5 m2 bench, I used 7 to 7.5 cm spacings)




These two pictures (above and below) of stenting with rootstock grafted before planting show excellent growth at just 2 weeks - the one bag over 3 tubes shows how humidity was maintained for the first few days before the "misters" were in place.  They are really just 180  micro-sprays with a timer that turns them on for 10 seconds every hour (every 3 hours at night).  This is all the hibiscus seem to need.  It is really only a matter of creating a bigger temperature difference between the top and the bottom of the cutting to speed up callusing and rooting.  These were grafted in 3's for a special order.

Above there are rootstock un-grafted at the back after 3 weeks, the same age or a day or so later stented plants at the right and a week old stented tray at the front left.  Below see a close-up of the stented lot.  Note the time waste - the back rootstock now needs grafting with a further 4-week spell on the hot bench whereas they could have been move to a shade house soon if stented originally.  However, we are still having zero plus or minus a couple of degrees each morning at the moment (August 17th) and moving things out is NOT an option yet!

These are week-old cuttings under the same conditions.  Below you can see I've included 3 stented grafts per tray for comparison.  The commercial trade prefers cutting-grown plants because of the lower cost of production.  It is possible to propagate 2000 cuttings in the time it takes to do 500 or so grafts - even though cuttings take several weeks longer to be ready for sale.  I'll see how they go on the hot bed over the next few weeks.  These have only been planted for 8-9 days.

An afterthought: this tray below show rootstocks from about 5-6mm to 10-12mm thick and my experience shows bigger is better - especially for speed to produce a plant in the garden.  I graft about 4 inches (100 mm) above the ground as most serious gardeners mulch - and a low down graft is quickly attacked by rot and bacteria if it gets covered with mulch and the like.

If you have any further queries, email me HERE

Visit the French Version Here - See also grafting in pictures and by cuttings