(status. last rev. January, 31, 2020, added data about sowing temperatures and propagators, needs some additions, clarifications)
Important note about the concept "soil":
It is imperative to give your sowing soil a lot of consideration! After all your young seedlings need to stay in that soil for around 1.5 year before they are large enough to be transplanted without the risk of massive losses! This implies that your mix should be as stable as possible both chemically and mechanically. One should try to avoid materials that will start "forming crusts" (typically pre-fertilized potting soils!) over time at the top of the soil. These crusts may strongly impair swift growth of the seedlings and it may even kill them due to severe alterations of the pH at the top. (all going alkaline and in high salt concentrations)
It cannot be emphasized enough that this soil needs some serious consideration.
It is almost compulsory to chose a soil mix that has very little "soluble" material. To keep the fresh seedlings upright, do use a thin layer of coarse material, sieved to 2-3 mm size grain. Chose topping materials that do not have a tendency to "clump/stick/or crust" together although that may be a strong function of the soil that is below. All sorts of "sand" are the very worst in this case. People always forget that in seedlings pots, there is a strong "upward" flow due to much moisture and evaporation at the surface. So everything that is dissolved in the water in the pot is transported to the surface where the water evaporates and leaves the dissolved materials back as a deposit which may form strong sticky crusts! It may ruin many sowing!
... and BTW ... do NOT sow seeds onto a wet surface. The seeds are very tiny, dry and very light so they will stick to anything wet on any surface and the seedlings will have an extremely hard time to send out their root into the depth. Mostly they fall over on their side and/or tip over, especially if light levels are too low (poor grow lights for example).
I also want to draw the attention that commercial growers do offer pots of Lithops that clearly have been raised in a 100% "potting mix" (sometimes mistakenly referred to as being "peat" which may/may_not be in the mix). One must realize that commercial growers have different aims for raising plants than the dedicated amateur. Ergo, the commercial grower does not care too much about survival rates as he wants to sell asap.
About Seeds:
For having an idea about how seeds look one may shortly revert to the item Seeds
An additional but important observation about seeds and their germination is as follows:
Why do "older" seeds have better germination than "fresh" seeds.
That is normal. It as been long known, also with other succulents, that fresh seeds contain high levels of inhibitor chemicals, produced by plant and/or seeds when the seeds start to ripen.
These inhibitors prevent premature germination of the seeds. The advantages are multiple. It prevents seeds from germinating right after they come off the plant while the conditions are still favorable but may become bad very soon after germination. It buys a "natural" delay for the seeds to germinate only at the next favorable long period of optimal conditions. The decay of those chemicals is "uneven" with time ie it may make seeds spread their germination over a very long period of time enhancing the chances for survival.
Those chemicals have decay times which can go over months up to several years. That's why those seeds stay viable for a very long time. Of course, all this is very dependent on genus and species, and the way the seeds are stored!
Read about seeds dormancy: Links => Seeds dormancy 1 Seeds dormancy 2
There are numerous advises on how to best store seeds. It is hard to say anything about what would be "the best" method but storing them in a secluded space, like in a plastic bag, is by far the very worst method. Tea bag type baggies (aerated) are supposed to be "the best".
All the so called "stratification techniques" that are used to make seeds germinate, whether they are chemical, physical or mechanical (scarification, sandpapering, freezing/thawing, chemicals like GA3 or fuming sulfuric acid treatment etc) are all aiming at breaking down those germination inhibitors much faster than in the normal way and make the seeds germinate "before their time" ie actually breaking the seed's dormancy. If these have an importance for enhancing Lithops seeds germination remains to be seen. Du eto th every small size of the seeds they can hardly be manipulated in several different methods. The only valuable method may be treating them with GA3, gibberallic acid, but no one knows what concentration of the compound needs to be used nor for how long. Values between 100 and 2000 ppm have been put forward and times from one hour to 24! The classic rule of thumb our labs used (blindly) was 1 gram per liter concentration, soak for 1 hour. (But if the seed coat is somewhat water repellent then what?)
Pots and Containers:
Basically, one can use any sort of container provided that it has adequate draining holes, can keep moisture inside and can be "covered" for some time. Any method that prevents that the soil falls through the bottom holes is ok as long as it is reasonably inert.
Also consider the different methodology of sowing directly in "pans" or "trays" which can easily be done but make sure the trays are deep enough from the start on. If not it may happen that the plantlets push themselves out of the soil after a while because their tap root is hitting the bottom of the tray. It is not a general rule but it certainly can happen. And of course putting pots in a shallow tray with a cover over them is also an option, but then there are so many ...!
What I use ...
Normally I'm using regular square pots in size 6 x 6 x 6.5 cm. Depending on the amount of seeds that I need to sow, I may divide the surface in two or even in four.
In am enclosing these pots in small plastic boxes with a tightly closing lid, 2 by 2. I'm putting a piece of capillary math in the bottom of the box which allows for swift watering from below. Keen observers may spot that the boxes are coming from chocolate boxes. (Rochers Ferrero). I was not the one eating the chocolates.
The pots fit tightly in the boxes. They will remain in those closed boxes for 3 to 5 weeks without being disturbed. Then, and after some inspection, the lid of the boxes will be put ajar allowing some air to come in and letting moisture escape gradually.
Substrate:
For the substrate, I can be very brief. I quite strictly follow the theoretical rules listed above.
I use a choice of compounds from the "Soil" page and my preferences are scoria, quartz, pumice and compost (worms castings, if available: anything "good potting soil" + home made compost, if not).
This year I wanted to use a soil slightly higher in moisture retention and in organic components so I used the following, just as an example:
4 parts pumice (2 Ikea + 2 Vulkatec)
4 parts black scoria
3 parts aquarium gravel 2-3 mm size
2 parts Akadama
All these compounds were sieved to remove the fines and "calibrated" to be 2 to roughly 3.5 mm in size, then mixed together.
For the organic fraction I used a mix of
3 parts worms castings
1 part "peaty" potting soil
The soil was composed by taking 3 volumes of the slightly moist mineral mix (to avoid component "fragmentation" aka unmixing due to specific weight differences of the compounds) adding one volume of the dry organic material. Mix well and that's it.
Addendum about Akadama:
I was able to find a large bag of Ibaraki Akadama 2-5 mm, so I'm using that as an enhancement of the sowing substrate. At this moment this is under test. First observations are that it must be used with caution as the Akadama seems to store a lot of water.
By default I do chose to *not* sterilize the soil other than by a chemical agent although I have used microwave sterilization.
Most people have a complete wrong approach of "sterilizing" soil in an oven or microwave. they roast the soil which delivers a biologically dead soil. The just "heat blast" the soil at maximum power. Then all the water quickly boils away allowing the soil to almost getting roasted and hereby destroying the soil structure and nutrients. As a result it is very well possible that such soil is getting "colonized" by the wrong micro-organisms when exposed to the environment. Not exactly what one wants.
Using a MWO implies to quickly warm up the moist soil to just under the boiling point of water (100°C) and to keep on that temperature by using short (2-3 minutes) burst at low power alternated with equally long periods of not warming, just to maintain that temperature for some 20 to 30 minutes. A good thermometer that can cope with those temps (preferably up to 120°C to avoid thatit explodes if the soil is getting overheated) is a very useful tool!
"Autoclaving" the soil in so called Weck glasses used for fruit and vegetables preservation also works very well and allows batches of soil to be stored for a longer time as long as the jars were prepared and "boiled" correctly (that is: including the rubber band sealing!)
Methods:
baggies, containers, free standing, anything else. pick your choice
Why is, seemingly, everyone so much in a panic for sowing Lithops?
Sure, one needs to be attentive and give seeds and seedlings good care, but they are hardly a big problem.
I know of cactus sowings that are much more complicated than sowing Lithops!
Sure, one needs to be attentive and give seeds and seedlings good care, but they are hardly a big problem.
I know of cactus sowings that are much more complicated than sowing Lithops!
Good, all this said let's put together some, hopefully, working info.
Let's talk "theory" first:
The basics are actually quite simple. A generally accepted method is to use a soil/substrate using a high ratio of "mineral" components, again, but not as stringent as for adult plants. A ratio between something 75/25 to 80/20 is mostly advised but it is not an irrevocable law, even 60/40 may work for you, and some even use 50/50! Room for experimenting if one has enough seeds.
The same rules as for adult plants apply. The substrate must be well draining and contain a low amount of "fines" that can clog up the soil and sieving out the dust from the mineral fraction is highly recommended (Before, I used and old flour sieve or a 0.3 mm mesh sieve, but now I'm even sieving out more fines, up to 0.5 mm using a kitchen strainer).
However, in comparison with adult plants, this substrate can have some more material to hold/store moisture for a longer time as this is beneficial for the growth of the seedlings, especially for root growth and survival. It is generally agreed upon that seedlings do require more moisture during their "childhood", the caveat being to pinpoint when this "childhood" ends, but it may well not be before one year. Some species may already turn into a more "succulent" behaviour after 4-5 months so it is the eye of the grower that needs to spot this and cut back on water accordingly. I'll be the first to admit that in an "all together" sowing setup this is really not an easy thing to manage but it can be done. (I consider my seedlings as "mature" at the start of the 3rd year after sowing).
All this can be achieved by playing on the amount of organic material or by using a higher ratio of "capillary" stones/material like pumice, vermiculite (small grain), lava/scoria, broken bricks and similar, versus hard stones, as can be found under "Soil & Potting".
Further conditions are that the sowing system must be kept moist, but not soaking wet, for some time and temperature controlled, day/night for a much longer time. Light of course is one of the key conditions for the good growing of the seedlings. Never assume that you have "enough" light at the place where you grow them, experience and all the questions that pop up around this, show that people always grossly overestimate the light yields in their setups. A lot of people start seedlings under artificial lights, which may be the way to go if one wants to sow early in the year and certainly if one has dark and gloomy winters. (like I have!). The key is to stick by the rules for illuminating seedlings which is to use at least 15000 to 20000 Lux, that is Lumen per square meter (10.76 sq ft) (see the grow lights chapter)
All the tools to, more or less, achieve this will be discussed below.
The same rules as for adult plants apply. The substrate must be well draining and contain a low amount of "fines" that can clog up the soil and sieving out the dust from the mineral fraction is highly recommended (Before, I used and old flour sieve or a 0.3 mm mesh sieve, but now I'm even sieving out more fines, up to 0.5 mm using a kitchen strainer).
However, in comparison with adult plants, this substrate can have some more material to hold/store moisture for a longer time as this is beneficial for the growth of the seedlings, especially for root growth and survival. It is generally agreed upon that seedlings do require more moisture during their "childhood", the caveat being to pinpoint when this "childhood" ends, but it may well not be before one year. Some species may already turn into a more "succulent" behaviour after 4-5 months so it is the eye of the grower that needs to spot this and cut back on water accordingly. I'll be the first to admit that in an "all together" sowing setup this is really not an easy thing to manage but it can be done. (I consider my seedlings as "mature" at the start of the 3rd year after sowing).
All this can be achieved by playing on the amount of organic material or by using a higher ratio of "capillary" stones/material like pumice, vermiculite (small grain), lava/scoria, broken bricks and similar, versus hard stones, as can be found under "Soil & Potting".
Further conditions are that the sowing system must be kept moist, but not soaking wet, for some time and temperature controlled, day/night for a much longer time. Light of course is one of the key conditions for the good growing of the seedlings. Never assume that you have "enough" light at the place where you grow them, experience and all the questions that pop up around this, show that people always grossly overestimate the light yields in their setups. A lot of people start seedlings under artificial lights, which may be the way to go if one wants to sow early in the year and certainly if one has dark and gloomy winters. (like I have!). The key is to stick by the rules for illuminating seedlings which is to use at least 15000 to 20000 Lux, that is Lumen per square meter (10.76 sq ft) (see the grow lights chapter)
All the tools to, more or less, achieve this will be discussed below.
Important note about the concept "soil":
It is imperative to give your sowing soil a lot of consideration! After all your young seedlings need to stay in that soil for around 1.5 year before they are large enough to be transplanted without the risk of massive losses! This implies that your mix should be as stable as possible both chemically and mechanically. One should try to avoid materials that will start "forming crusts" (typically pre-fertilized potting soils!) over time at the top of the soil. These crusts may strongly impair swift growth of the seedlings and it may even kill them due to severe alterations of the pH at the top. (all going alkaline and in high salt concentrations)
It cannot be emphasized enough that this soil needs some serious consideration.
It is almost compulsory to chose a soil mix that has very little "soluble" material. To keep the fresh seedlings upright, do use a thin layer of coarse material, sieved to 2-3 mm size grain. Chose topping materials that do not have a tendency to "clump/stick/or crust" together although that may be a strong function of the soil that is below. All sorts of "sand" are the very worst in this case. People always forget that in seedlings pots, there is a strong "upward" flow due to much moisture and evaporation at the surface. So everything that is dissolved in the water in the pot is transported to the surface where the water evaporates and leaves the dissolved materials back as a deposit which may form strong sticky crusts! It may ruin many sowing!
... and BTW ... do NOT sow seeds onto a wet surface. The seeds are very tiny, dry and very light so they will stick to anything wet on any surface and the seedlings will have an extremely hard time to send out their root into the depth. Mostly they fall over on their side and/or tip over, especially if light levels are too low (poor grow lights for example).
I also want to draw the attention that commercial growers do offer pots of Lithops that clearly have been raised in a 100% "potting mix" (sometimes mistakenly referred to as being "peat" which may/may_not be in the mix). One must realize that commercial growers have different aims for raising plants than the dedicated amateur. Ergo, the commercial grower does not care too much about survival rates as he wants to sell asap.
About Seeds:
For having an idea about how seeds look one may shortly revert to the item Seeds
An additional but important observation about seeds and their germination is as follows:
Why do "older" seeds have better germination than "fresh" seeds.
That is normal. It as been long known, also with other succulents, that fresh seeds contain high levels of inhibitor chemicals, produced by plant and/or seeds when the seeds start to ripen.
These inhibitors prevent premature germination of the seeds. The advantages are multiple. It prevents seeds from germinating right after they come off the plant while the conditions are still favorable but may become bad very soon after germination. It buys a "natural" delay for the seeds to germinate only at the next favorable long period of optimal conditions. The decay of those chemicals is "uneven" with time ie it may make seeds spread their germination over a very long period of time enhancing the chances for survival.
Those chemicals have decay times which can go over months up to several years. That's why those seeds stay viable for a very long time. Of course, all this is very dependent on genus and species, and the way the seeds are stored!
Read about seeds dormancy: Links => Seeds dormancy 1 Seeds dormancy 2
There are numerous advises on how to best store seeds. It is hard to say anything about what would be "the best" method but storing them in a secluded space, like in a plastic bag, is by far the very worst method. Tea bag type baggies (aerated) are supposed to be "the best".
All the so called "stratification techniques" that are used to make seeds germinate, whether they are chemical, physical or mechanical (scarification, sandpapering, freezing/thawing, chemicals like GA3 or fuming sulfuric acid treatment etc) are all aiming at breaking down those germination inhibitors much faster than in the normal way and make the seeds germinate "before their time" ie actually breaking the seed's dormancy. If these have an importance for enhancing Lithops seeds germination remains to be seen. Du eto th every small size of the seeds they can hardly be manipulated in several different methods. The only valuable method may be treating them with GA3, gibberallic acid, but no one knows what concentration of the compound needs to be used nor for how long. Values between 100 and 2000 ppm have been put forward and times from one hour to 24! The classic rule of thumb our labs used (blindly) was 1 gram per liter concentration, soak for 1 hour. (But if the seed coat is somewhat water repellent then what?)
Pots and Containers:
Basically, one can use any sort of container provided that it has adequate draining holes, can keep moisture inside and can be "covered" for some time. Any method that prevents that the soil falls through the bottom holes is ok as long as it is reasonably inert.
Also consider the different methodology of sowing directly in "pans" or "trays" which can easily be done but make sure the trays are deep enough from the start on. If not it may happen that the plantlets push themselves out of the soil after a while because their tap root is hitting the bottom of the tray. It is not a general rule but it certainly can happen. And of course putting pots in a shallow tray with a cover over them is also an option, but then there are so many ...!
What I use ...
Normally I'm using regular square pots in size 6 x 6 x 6.5 cm. Depending on the amount of seeds that I need to sow, I may divide the surface in two or even in four.
In am enclosing these pots in small plastic boxes with a tightly closing lid, 2 by 2. I'm putting a piece of capillary math in the bottom of the box which allows for swift watering from below. Keen observers may spot that the boxes are coming from chocolate boxes. (Rochers Ferrero). I was not the one eating the chocolates.
The pots fit tightly in the boxes. They will remain in those closed boxes for 3 to 5 weeks without being disturbed. Then, and after some inspection, the lid of the boxes will be put ajar allowing some air to come in and letting moisture escape gradually.
In this picture one can see the capillary mats, cut to pieces to fit, which I put on the bottom of the plastic containers. These are a terrific help in distributing water/moisture evenly, all over the bottom of the container.
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For small quantities of seeds I may use the round, classic 5,5 cm pots which usually come in red or black plastic. The are also used in the same way as the square ones ie they are stored in a "closed system" to start with.
Temperatures and how to maintain them:
Most Lithops habitats seem to have moderate average temperatures, if one has to believe climate graphs but the extremes may show a very divergent behaviour ! ... nevertheless ...
What I use ...
For all my sowing I use one or more propagator(s). They may be commercially bought or home made.
My aim is to get a germination temperature, not much higher than 25°C during the day and basically not much lower than 17°C during the nights. These temperatures are an approximation as one must take into account the "hysteresis" of the heating element and the propagator. That is why I am setting the temperature to 24°C on the thermostat so the "overshoot" is not getting too high. The night temperature is not too critical, setting 16-17°C on my thermostat works well as it can only switch per 0.5 degree C.
The question often arises, what if my temperatures are much higher? Apparently seeds germination rate is considerably pulled down if the temperatures are high all the time. Temperatures like 30°C all the day time may not be your best bet, certainly if that is accompanied by high temperatures during the night. (above 22°C?) One may also notice that seedlings start to stall growth when temperatures rise too high. (summer dormancy?) With the changing climate, even here up North this starts to be a problem during the summers and in the greenhouse!
I'm not making any ad here but I have been using the following thermo-timer with quite some success for a very long time (Actually, I have 4 of them because of their versatility). It is the TFA Dostmann Thermo-Timer 37.3000. It goes for about €33.50 on the internet.
Temperatures and how to maintain them:
Most Lithops habitats seem to have moderate average temperatures, if one has to believe climate graphs but the extremes may show a very divergent behaviour ! ... nevertheless ...
What I use ...
For all my sowing I use one or more propagator(s). They may be commercially bought or home made.
My aim is to get a germination temperature, not much higher than 25°C during the day and basically not much lower than 17°C during the nights. These temperatures are an approximation as one must take into account the "hysteresis" of the heating element and the propagator. That is why I am setting the temperature to 24°C on the thermostat so the "overshoot" is not getting too high. The night temperature is not too critical, setting 16-17°C on my thermostat works well as it can only switch per 0.5 degree C.
The question often arises, what if my temperatures are much higher? Apparently seeds germination rate is considerably pulled down if the temperatures are high all the time. Temperatures like 30°C all the day time may not be your best bet, certainly if that is accompanied by high temperatures during the night. (above 22°C?) One may also notice that seedlings start to stall growth when temperatures rise too high. (summer dormancy?) With the changing climate, even here up North this starts to be a problem during the summers and in the greenhouse!
I'm not making any ad here but I have been using the following thermo-timer with quite some success for a very long time (Actually, I have 4 of them because of their versatility). It is the TFA Dostmann Thermo-Timer 37.3000. It goes for about €33.50 on the internet.
It is an extremely versatile tool as it has 3 time spans to which a temperature can be linked. So one can set a first time span to cover 6 am to 9 am at 19°C, then from 9 am to 8:30 pm having 24°C and then from 8:30 pm to 6 am 17°C. But one does not even need to use all 3, one can just disable a time span.
Making a home built propagator is childishly easy. Get an appropriate sized styrofoam tray, line it with kitchen tin foil to reflect light. Buy an appropriate sized heating mat. Put some "metal plate" in the bottom to put the mat on so it does not stick to the styrofoam when warming up. A glass plate on top and that's it.
Heating mats/pads can be easily found for horticulture or in reptile pet shops. Make sure you have the sealed type so water or moisture cannot get in!
Use the above thermostat-timer and you're all set!
This propagator is what I use, exactly the same model, a plastic tray surrounded with a special heat resistent foam coating and a 50 Watts electric heating inside. Here the whole set, including the thermostat, can be bought here for €100 or thereabout.
Side note : for the ease of manipulation, I removed that nice plexiglass/perspex cover and replaced it with two removable glass plates. The advantage is that the volume is smaller which cuts down on the heating cost and the plates can easily be removed for watering and close inspection. Just an aside ...
For the substrate, I can be very brief. I quite strictly follow the theoretical rules listed above.
I use a choice of compounds from the "Soil" page and my preferences are scoria, quartz, pumice and compost (worms castings, if available: anything "good potting soil" + home made compost, if not).
This year I wanted to use a soil slightly higher in moisture retention and in organic components so I used the following, just as an example:
4 parts pumice (2 Ikea + 2 Vulkatec)
4 parts black scoria
3 parts aquarium gravel 2-3 mm size
2 parts Akadama
All these compounds were sieved to remove the fines and "calibrated" to be 2 to roughly 3.5 mm in size, then mixed together.
For the organic fraction I used a mix of
3 parts worms castings
1 part "peaty" potting soil
The soil was composed by taking 3 volumes of the slightly moist mineral mix (to avoid component "fragmentation" aka unmixing due to specific weight differences of the compounds) adding one volume of the dry organic material. Mix well and that's it.
Addendum about Akadama:
I was able to find a large bag of Ibaraki Akadama 2-5 mm, so I'm using that as an enhancement of the sowing substrate. At this moment this is under test. First observations are that it must be used with caution as the Akadama seems to store a lot of water.
By default I do chose to *not* sterilize the soil other than by a chemical agent although I have used microwave sterilization.
Most people have a complete wrong approach of "sterilizing" soil in an oven or microwave. they roast the soil which delivers a biologically dead soil. The just "heat blast" the soil at maximum power. Then all the water quickly boils away allowing the soil to almost getting roasted and hereby destroying the soil structure and nutrients. As a result it is very well possible that such soil is getting "colonized" by the wrong micro-organisms when exposed to the environment. Not exactly what one wants.
Using a MWO implies to quickly warm up the moist soil to just under the boiling point of water (100°C) and to keep on that temperature by using short (2-3 minutes) burst at low power alternated with equally long periods of not warming, just to maintain that temperature for some 20 to 30 minutes. A good thermometer that can cope with those temps (preferably up to 120°C to avoid thatit explodes if the soil is getting overheated) is a very useful tool!
"Autoclaving" the soil in so called Weck glasses used for fruit and vegetables preservation also works very well and allows batches of soil to be stored for a longer time as long as the jars were prepared and "boiled" correctly (that is: including the rubber band sealing!)
Methods:
baggies, containers, free standing, anything else. pick your choice
The old method of sowing in baggies sure can be done for Lithops but it is not the best suited as one needs to open the baggies after germination or at best after 4-5 weeks to avoid fast wilting by fungal attacks. Species that can cope with more water (lesliei, aucampiae) can be kept in baggies for 8-9 months but then it also becomes problematic. cacti can be kept sealed in for certainly two years without much troubles. It won't work for Lithops. A couple of examples below.
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I prefer by far to use individual pots that are locked away in a clear plastic container with lid. This allows for keeping the seeds in a closed but humid environment for the time of the germination and even a couple of weeks later without having to bother much about watering levels and schedules. Once the seedlings are well established I put the lids ajar over the boxes to allow for air to come in. From there on a regular inspection and watering is needed.
Updated setup: The cheap led array grow light is a clumsy thing, not very durable and it is a pain to complement it with discrete lamps or beamers. So I decided to abandon it and replace it by two additional 50W beam grow lights. If I live long enough I may chose to remove some of the red leds and replace them with more blue ones.
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Mostly I do try to sow early in the year (Dec-Jan) so I use a propagator and artificial lights. But by the end of April, beginning of May the whole batch of pots + seedlings are moved into the greenhouse. They go *under* the benches with filtered natural light. "Under the benches" because it is cooler there.
A couple of things are nevertheless becoming problematic over these last years. The global warming has caused us to get very warm summers, even up here North, and the greenhouse is becoming incredibly hot which in term seems to cause that the seedlings stall growth in that heat. Not very funny!
How I fill my sowing pots:
Here is a schematic of what is in my pots:
- 1: a small layer of moist coir/cocopeat, compressed with a small wooden stick. mainly a plug to avoid that the soil falls through the holes in the bottom.
- 2: A thin sprinkle of fungicide "diluted" with stone flour. I use "Thiram" ... Link => What is Thiram?
- 3: The substrate
- 4 - 5 : The seeds with, again, a thin layer of fungicide over them.
- 6: a thin sheet of sieved black scoria to hold up the tiny plants once they germinated.
A sowing trick:
People do ask how I manage to spread the seeds over the surface of the pots.
Indeed, many times, and due to the every small size of the seeds, spreading them more or less evenly over the soil surface is a bit problematic. They then to kind of "clog" together and end up on the soil in a small heap.
For me the solution is simple. I use a "sowing gutter". No hi-tech stuff but a small piece of shiny, polished aluminium folded in a V-shape.
The seeds are poured into the gutter, right from the bag or container. Then the gutter is held almost horizontal, but slightly slanted towards the soil surface and lightly tapped on one of the wings with the spatula. Due to the vibration of the gutter, the seeds start to dance away towards the soil in an almost "mono-line" (line dance LOL) through the gutter. They fall off the gutter onto the soil and one can just gently move the end of the gutter over the whole surface. Job done!
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Initial watering:
The pots are been filled according to this scheme with dry materials, except for that bottom layer. Now I just water them carefully in order not to disturb the top layer. I know, by good approximation, how much water the substrate can hold, so I just "under water" the pot. This means the water is *not* running out through the holes below. Then I moisten the capillary tissue in the containers. Just equally moist, not sweating wet. Then I put the pots in the boxes and firmly fix the lid. They won't be opened for at least the first 3-5 weeks depending on species.
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After 12 to 14 months they should, more or less, look like this ....
There is a general guideline at the manolithops Spanish site (translate it from Spanish with google, see Links & Books) ...
It may be your good starting guide for watering seedlings.
Link to: Growing from seeds according to Cole
BUT !!
You must realise that this person lives in Spain, in a rather dry and warm, if not hot, climate and he may be using an hyper draining soil! If you do not have similar conditions then you are at the risk of grossly overwatering your seedlings and they may just all disappear overnight!
It may be your good starting guide for watering seedlings.
Link to: Growing from seeds according to Cole
BUT !!
You must realise that this person lives in Spain, in a rather dry and warm, if not hot, climate and he may be using an hyper draining soil! If you do not have similar conditions then you are at the risk of grossly overwatering your seedlings and they may just all disappear overnight!
I did removed the translated text I had included here because people were thinking that it was MY seedlings watering method which it is not!