A Batch of Clones in Rockwool

[Al B. Fuct]

A lot of people have trouble with clones in rockwool until they have done a few batches. Here's a photoessay on a batch of clones as they are done around here.

One of the biggest problems with rockwool cubes is that they can hold a LOT of water. If cubes are too wet, rooting will be slow or stem rot may set in. Think damp, never wet or saturated. A dry 40mm cube weighs 5g. A properly "damp" cube weighs 25-30g. Heavier than that is too wet. Remove water from overwet cubes by shaking excess out into a bucket with a snap of the wrist. A salad spinner is great for draining cubes after pre-soaking, without giving yourself 'tennis elbow.' Rockwool cubes must never be squeezed- removes airspaces.

Since I grow SoG style, I cut very tall clones. Taller clones become taller plants faster- important in SoG as no vegging time is given to clones before they are flowered. As soon as they have a good set of roots, they go in to the flowering area.

My clones are too tall to fit in a humidome, but humidomes usually keep things TOO humid anyway, especially when using rockwool cubes on a heatmat.

Clones do best in a controlled environment, so I built a clonebox with 3x twin 18W fluoros (on 24/7), a fixed-temp (30C) heat mat and a thermostatically controlled exhaust fan. The ballasts on the fluoro lights put a fair amount of heat into the box air. When the temp comes up to 26.5C, the fan kicks on.

So, here we go!

First, sterilise all plant contact surfaces (trays, inside of clonebox) with a 10% bleach in warm water solution. 1-2 drops of dishwashing soap helps make the cleaning solution "wetter," assuring every little nook and cranny is germ-free. Rinse and allow to dry. Don't forget to wash your hands thoroughly with the same solution- use a fingernail brush.


These mother plants are about 6 weeks old. They've donated about 3 sets of cuttings and will be replaced with one of their 'kids' soon.

Note that these are only two of my mothers. I keep 8-10 mothers to support donation of 30 cuttings every 15 days. Mothers are vegged under a 400 HPS (soon to be a metal halide).


Rockwool cubes are first rinsed well under running tap water then pre-soaked in a bucket of pH5.0 water for 24 hours. All the pre-soak water is removed with a salad spinner.

Immediately before plugging in cuttings, cubes are each given about 25ml of a clone watering solution made from:

* 9-10L tapwater
* 9-10ml H2O2 (50% horticutural grade)
* pH adjust as needed to 5.8 (correct pH last)

The nutrient is not entirely necessary- a plant without roots can't assimilate nutrients, only water- but nutes in the clone watering solution assures nutes are available to the plant as soon as it has formed root nodes. This gets nutes to the plant a day or two before you actually see the roots out of the bottoms of the cubes. Well developed mothers in good condition will have a couple of weeks worth of nutes stored in the leaves- and so will the clones you take from them.


A well developed mother plant about 4 weeks old. Has donated about two passes of cuttings.


Sterilise the scalpel blade by dipping in methylated spirit (aka denatured alcohol) before and between making cuts


I cut BIG clones. Stem length is about 9".

Cut the biggest diameter stems you can get for clones. This is how they look when just cut off the mother. Make the stem cut at an angle, about 45 degrees.


Cut off all the branching until you have something like this.


Split the end of the stem. Disrupted cells on the stem more easily become root nodes.


Gently scrape the last 25mm (1") of the stem in a few places with the back of the scalpel blade.


Dip the stem in rooting powder. Gently knock off any excess; only a dusting is needed.

Powders work better than gels because they form a paste which stays put through several waterings.

Gels can support pathogen growth in between batches. If you use gels, put a few ml in a small container and dip stems into that gel- not in the main container. Discard any excess. Even opening the gel container will admit a few pathogens. Once opened, keep gels in the refrigerator.


Plug the stem into the cube, using care not to poke through the bottom of the cube.

It is important that the rockwool fits tightly around the stem. Some cubes are not very dense in some parts of the cube. Test the density of the rockwool by touch and plug the stem in the densest part of the material. Some cubes collapse when you try to plug a stem in them. Discard cubes like this. The air gap between the stem and cube will prevent proper rooting.

Clone #1 done!


Big clones work better in Sea of Green. There's no veg time given to clones in SoG before flowering. Bigger clones make bigger budstalks. As you see, these are about 9" tall.


Now, let's prune back the mothers.

Some stems are too small to make cuttings with on this pass. We'll take cuttings from these stems when they have developed more in about 2 weeks.

Snip off the growing tip to force growth to divide. Leave the leaves and the following nodes- these sites will develop into cloneable branches on the next pass of cuts in 2 weeks.


Mother plant pruning detail. Growing tips gone but the next nodes down are not disturbed.


Mother plant pruned and ready to go back in & veg for 2 weeks until the next batch of cuttings is needed. "Before" pic repeated here for comparison.


A freshly done batch of clones in the clonebox.


Roots pop on day 6-7.


Roots on day 8.


21/30 strikes on day 10.


And here we are on day 10. No yellow leaves! Yellowing leaves are a sign of excessively high air temp or overwatering. Cubes in the left-hand tray have not set root just yet. I only need 20-21 clones per flowering batch. Extras become mother plants- or compost!

The clonebox conditions and getting the watering right are EVERYTHING. Quick rooting with the plants in best shape is dependent upon several things; I consider a heatmat to be an essential. Thermostatic control of air temp makes striking time reliably 6-7 days, every time.

 

[midgradeindasouth]

damn send some clone compost to me why don't ya

 

[Al B. Fuct]

middie, I make POUNDS of cutting waste- and it does feed my veg patch out back very, very well.

You don't really need a 400 over your mums just to get some cuttings, but I get really fat stems and bigger-than-your-hand fan leaves on the mums during the mums' 2-week recovery period with a big light. I use an HPS because that's what was on hand many years ago when it was retired as a flowering light when I got the 1000s- and it works fine, so I never changed it to MH. I'm thinking about an HPS-MH conversion lamp soon, though.

I grow a lot more mother plant material than I REALLY need just to do the cuttings. Overgrowing the mothers a bit assures top quality material for cuttings, though there is a bit of plant material wastage.

 

[mosberg911]

ok Al if i put them clones straight into flower how much bud do you really get out of clones a good amount?>

 

[Al B. Fuct]

We deliberately grow small plants in SoG; the per plant yield is thus rather small compared to other methods- but we grow greater numbers of plants than in other methods. One plant per 8" circle. This is made possible without crowding by aggressive pruning off of all the branching on the lower 1/3 of the plant. No branches more than about 25mm (1") long are left on a SoG style plant.

However, the buds you get from SoG are ALL top colas or the very large clumpy lumps attached near the top of the mainstem. They all live very close to the light, meaning no small, fluffy buds, only dense, top quality golfball or bigger nuggies.

I'm doing well to get 3/4-1oz per budstalk under 1000W lighting. Sometimes I do better but rarely worse. Out of my 20-21 plants per harvest, I normally get somewhere between 15-20oz.

This room is still kinda new, only about 6 mos old since a rebuild in a new location, so I'm still tweaking and fixing things. I've made some improvements recently (better ventilation with a new exhaust blower) which are making my buds much denser as I'm better able to keep temps down. Running the flowering area at 25C now- and everyone likes it.

 

[FlipAPenny]

You need to put this thread with the other threads that are written in red. This is great work Al!

Thanks for the info.

I think I am going to have to fly you out so you can put a grow room together for me. I'm gettin' a chubby just thinkin' about that

 

[Al B. Fuct]

You need to put this thread with the other threads that are written in red.

Done.

This is great work Al!

Thanks for the info.

You're quite welcome, happy to share what I know.

I think I am going to have to fly you out so you can put a grow room together for me. I'm gettin' a chubby just thinkin' about that

heh, thanks for the offer, but I think I'm happy not moving around much at the moment.

 

[Al B. Fuct]

Roots develop FAST.


day 10 ..................................................... day 12

Stem diameter of cuttings makes a difference with the vigor of rooting speed and development. Bigger is better.



Thicker stemmed cuttings outperform thinner ones. The stack on the left all have stems of about 4mm or less. The stack on the right all are over 5.5mm.

If I grew a couple more mother plants, there'd be enough >5mm stems to do all my cuttings, but unfortunately the mother plant tray is full- so we'll just hafta get by with wot we got.

 

[Al B. Fuct]

It's trouble that everyone should have, but I have a small complexity introduced by clones being ready to plant a little sooner than usual this time around. I've only recently added the thermostat to the clonebox. The more stable temperature has made it about 3-4 days quicker than before. The speed of first roots showing is about the same as before adding the thermostat, but the development of profuse roots has come around much more quickly.

I would normally be doing a new batch of cuttings on the day I plant out the preceding batch. However, in this case, because the flowering area is on a 2-week rotation, I'll have to delay doing another batch to avoid feeding clones into the flowering room too quickly and having to remove plants from the other end of the pipeline before they are fully mature.

Since the clonebox looks like it will have future batches ready for planting in 12 days instead of 15, I'll time my next batch of clones accordingly.

 

[VictorVIcious]

I'm working on creating that problem. I did get one of my tables converted to flood and drain instead of drip. Will get one more converted this week and then I'll start building the last table I need to get it all set. VV

 

[Al B. Fuct]

Sounds good, VV. Whatever you can do to automatically manage conditions will make things happen more reliably. I've gotten by for many years without a thermostat in the clonebox, but as you might expect, air temps were all over the shop dependent upon the ambient air temp around the clonebox. When ambient was around 23-25C, the lights warmed the interior of the box to an ideal 26.5-27C with the fan constantly running. When ambient was really low, I managed temp by running the fan on a timer, 15 mins on, 15 mins off. Worked sorta OK, but I expect the clonebox to be much more consistent now with the tstat installed. Moreover, minding the clones is easier when the temps are stable. An unexpectedly warm day might cause the cubes to dry out more quickly than usual, leaving me with wilted or cooked clones when I water at the usual time of day.

You'll like the improvement in reliability of a flood system- they simply can not clog from nute salts as there's no small sprayer or dripper apertures. Much less maintenance.

 

[VictorVIcious]

I put the fourth table on flood and drain yesterday. Still have a few things to do. I have the mother table set and ready. Have clones in it now. The other three are all in flowering, two weeks apart. I replaced two of my 400watt lights with t-5 4' 8 bulb fixtures. I like what I see so far. The first harvest will be of those clones I took from the flowering plants, so they have multiple branches instead of the single cola so I will probably get a lower yield from them. We have had hot, humid weather for a few weeks now so everything has slowed down a little. I figure another three months I should have it all going smooth.

 

[weedbro]

when you cut clones do you just give them water until they start growing roots by just spraying the leaves. Or do you start giving the clones nutes right away? Just wondering how the feeding process works for clones with no roots. thanks

 

[TheConstantGardner]

when you cut clones do you just give them water until they start growing roots by just spraying the leaves. Or do you start giving the clones nutes right away? Just wondering how the feeding process works for clones with no roots. thanks

Nutes aren't needed until roots form. Until roots form, you are only concentrating on gaining roots and not foliage. I give my clones very mild nutes as soon as roots appear, then aggressively up the nutes as the plant starts producing new vegetation.

 

[VictorVIcious]

Constant gardner is right you don't have to give nutes until roots are out. Al B uses mild nutes in the water he puts in his rockwool cubes. Since he has better results then I get I'm going to try his way. VV

 

[potroast]

I use mild nutes and especially SuperThrive in the water that I soak cubes, rewet cubes, and foliar spray the cuttings with. I root 40 cuttings a month, and get near 100% rooting.

HTH

 

[TheConstantGardner]

I use mild nutes and especially SuperThrive in the water that I soak cubes, rewet cubes, and foliar spray the cuttings with. I root 40 cuttings a month, and get near 100% rooting.

HTH

I mist with a couple drops of superthrive and water, which usually ends up wetting the top of my medium. My clones are small, so it's getting down to the root zone. I may have to try the rockwool cubes soon. Perlite/vermiculite is as friggin messy as soil.

 

[weedbro]

ya im going to be cutting some clones in the next couple of weeks and ill be sticking them in rockwool so its nice to know that you can soak the cubes with a little bit of nutes. i had have soil and half rockwool that i started seeds in and i didnt give the ones in rockwool anything for awhile and they are wayy behind the ones in soil

 

[Al B. Fuct]

Constant gardner is right you don't have to give nutes until roots are out. Al B uses mild nutes in the water he puts in his rockwool cubes. Since he has better results then I get I'm going to try his way. VV

Quite true that clones can't make any use of nutes until they have roots, but in rockwool cubes you don't see the roots from the very instant nodes have formed. You see them a couple of days later. Putting a weak nute soln (~400ppm, 5ml Canna Vega "A" & "B" in 10L water, corrected to pH 5.5) on the clones means they can get at the nutes a couple of days before you see them out of the bottom of the RW cube.

FYI, I'm not checking in here regularly these days. Check me out over here.

 

[Al B. Fuct]

Just a quick followup on refining the cloning environment process.

I had a few batches root slowly and coincidentally came across anecdotal evidence of nitrogen slowing rooting performance. I stopped adding nutes to the watering soln, instead just correcting pH to ~5.5-5.8. The last batch done like that popped first roots at 6 days with profuse roots at 10 days. I'll do the next batch the same way and see if I get the same result. Then I'll try it again with a weak vega nute soln (~400ppm) and see if the strike time is slower.

I ran a small circ fan in the clonebox in the coldest months, where the ambient around the clonebox can get down to 10c. This moves some heat off the fluoro ballasts and raises the box to the setpoint of 26-27C. However, this fan caused the cubes to dry out much more quickly, requiring 2x day watering. As spring has come on, I have switched off the circ fan.