Commercial growing

[Spikylover]

First off, i know i ask about this topic too much but there's so much i still don't know.
My inquiry today is about seed starting. I usually discover some sort of coarse sand (2-3mm) in most if not all the cacti i buy close to the crown of the roots or embedded in the body. This lead me to do some research and find some information i need to verify because i didn't find any solid reference. I guess growers don't share this knowledge.
1. Starting medium: Some resources suggest seeds are started purely in this coarse sand while i've seen some pictures (uhlig kakteen) where the sand only covers the surface of the organic soil. Which is it?
2. Purpose of the sand: some rwsources suggest the sand is used to prevent mold and algae at the surface. Correct?
3. Seeds: are the seeds sprinkled on the very top or covered by a layer of coarse sand?
4. Watering: i have not found any source using any variation of the baggy method. What i understand is that seeds are sown in flats (or sometimes plugs), placed on cappillary mats and the surface is covered. 2 weeks after seedlings emerge, top cover is removed. Does this sound correct?
I really hope to find answers. I am just a college student with a humble collection. Im not looking to start a nursery!
Thanks in advance

Rachel

[DaveW]

Part way through this video you will see a Dutch firms seed raising technique where all the seed flats are covered with polythene sheet until they germinate.

https://www.youtube.com/watch?v=4JdGny9_bjM

I have used many methods over the years and as you say some use coarse sand on top to suppress algae and also help initial root penetration. However I have also used a 1cm (3/8") layer of coarse potting grit on top of my usual potting compost mixture (Brits call potting soil mixtures, potting compost, without meaning the rotting vegetable matter used as a manure) and sprinkled the seed on to it then just washed the seed into it with a fine mist spray. I find this layer inhibits both algae and sciara (mushroom) fly, holds the germinating seed up and allows the roots to penetrate and any seedling that dies does not easily infect the others and is easy to remove. This method can be used in baggies or with most other methods.

SEED.png (49.32 KiB) Viewed 1091 times

grit.jpg (128.89 KiB) Viewed 1091 times

[Spikylover]

That's awesome dave thanks!
One question though...so you do use an organic mixture for starting seedlings and later on go mineral? Why not go mineral from the start?
Also i've noticed with most members that seedling are concentrated in one area instead of spread over the pot. Is that a coincidence or you actually plant them close?

[ElieEstephane]

Hello Rachel. I have started seeds using only grit and seedlings seem much stronger than their non grit counterparts. Algae is severly suppressed. And if you see any algae forming, you can simply pick off that single rock with a spoon or tweezers. Growth is slower but stronger.

[DaveW]

My compost, or potting soil, tends to be whatever is "flavour of the month" since like many I have tried them all. Most of us are always looking for something that grows the plants better in our conditions. I suppose with seedlings it depends how long they are left in the pot or container before being pricked out.

With plants in the old conventional UK cactus composts such as John Innes numbers 1 to 3, plus up to 30% extra grit, there was enough nutrients in the pot to last for a year without fertilisation (the only difference between 1 to 3 is the amount of fertiliser added and these days a normal balanced commercial fertiliser has replaced the old recipe). No doubt seedlings being smaller they could last longer.

With mineral composts you may need to fertilise sooner, but too much fertilisation is not recommended for seedlings. As my dad used to say "you don't feed babies beefsteaks, it will make them sick". Even John Innes commercial seed compost cuts down the amount of fertiliser compared to the normal plant growing ones and that was for normal plants. not slow growing cacti. Plants also tend to make a better root system if they have to search a little more for nutrients.

https://www.gardeningdata.co.uk/soil/jo ... _innes.php

The seedlings are concentrated in one area Rachel as I did not manage to scatter the seedlings evenly over the pot and seldom do. However I know somebody who does set seed individually, in his case using a tiny screwdriver and just dipping the end in water to wet it and pick up and plant an individual seed. But I don't have that patience, particularly if sowing numerous packets, many with small seeds.

[DaveW]

The peat based composts were largely introduced by the University of California, who came up with peat based composts to replace JI ones since virgin loam was hard to obtain and very variable as garden or yard soil was usually substituted for it. UC compost mixes were also published in one of the early American Journals for growing our plants.

http://afghanag.ucdavis.edu/natural-res ... _Mixes.doc

Here was the UC Succulent Compost:-

"University of California Succulent Mix
1 part ground sphagnum peat
1 part redwood compost
1 part horticultural sand
2 parts volcanic pumice
for every one cubic foot of mix add:
5 tablespoons dolomite limestone
2 tablespoons gypsum
3 tablespoons superphosphate
1 teaspoon potassium nitrate
1/2 teaspoon potassium sulphate

The familiar peat composts Dutch store bought plants come in, just comprising peat and sharp sand was known Levington compost in the UK, the name of the firm that introduced it. It was also used for growing cacti with up to 30% grit added, as with JI compost. The UK does not normally use redwood or pumice in it's composts. Pumice because it is expensive as we have no indigenous sources of it so it is all imported.

[Spikylover]

Thank you dave! Im still kind of scared to use an organic mix for the seeds but i will try your method with one batch and see what happens!

[DaveW]

You can still use a layer of coarse grit on top of your normal mineral mix, you don't have to use an organic mix. It is just that the larger gaps between the grit hold the seedlings up better until they root into the finer layer below and algae cannot spread so easily on the more granular surface.

I did ask an English cactus wholesale grower how he managed to grow cactus plants so well and quickly in Continental type peat mixes? He said they use a wetting agent in the peat compost. How long this lasts I do not know, but presume they would have to fertilise also, so whether they also use a wetting agent in the watering water I do not know.

I believe a few drops of washing-up liquid in the water will act as a wetting agent for mainly peat composts, but it usually contains salt. However whether that is enough to matter in such a small quantity is debatable. Usually these wetting agents are just some form of soap anyway, so a bit of ordinary soap just briefly swirled in the water would probably help to re-wet peat composts. You can use soap suds to kill mealies and spider mite, so some getting into the soil does not usually affect the plants.

[ElieEstephane]

Any surfactant can be used to improve the wettability of the soil. It's just like the surfactants in detergents act on non polar fat matter on dirty clothes and remove it. The same way, organic soil is non polar and thus you add surfactants to wet it. Using plain soap would be best and as dave said it can act as an insecticide. What percentage of soap in water to use i don't know. I suspect that you definitely need to cross the critical mycelle concentration. I read on your profile that you are a chemical engineering student so you should understand and and know how lo apply this.

[Spikylover]

How do i find critical mycelle concentration of you don't mind me asking?

[ElieEstephane]

You can't just "find" the cmc. You need lab euipment. But i will try to simplify it for you. When you add small amounts of surfactant to water, it alligns it self at the liquid interface and you reduce the surface tension. Keep adding small amounts and you can still decrease the surface tension up to a point where the liquid interface is saturated with surfactant and any surfactant you add beyond this point will migrate to the bulk if the liquid. This is your critical mycell concentration. It's when the surface tension is decreased to a new constant.

[ElieEstephane]

I will pm you more details if you are interested

[jp29]

I have always experimented with soil mixes -- like DaveW, I have used about every one that has been devised during my growing lifetime (including strictly mineral mixes) and I have found all those that were of coarse and gritty texture, thus providing excellent drainage and root aeration, consistently produced healthy and robust plants. For the past year or so I have used the following organic mix for my mature container grown plants, seedlings and seed germination:

80% Bach's Cactus Nursery mix plus 20% raw pumice (with coarse crushed granite top dressing).

Dan Bach's Cactus Nursery mix:
60% screened coarse horticultural pumice
20% high quality Canadian sphagnum peat moss
20% well composted shredded pine tree forest bark

The melocactus matanzanus seedlings shown at the lower right in the following photo were germinated using the baggie method this past August - I just sprinkle the seeds on the surface and they trickle down among the crushed granite:



They are presently staged in full sun without any covering during the day and brought indoors on the windowsill at night.


James
http://jp29.org/index.htm
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[DaveW]

I don't think we both go back quite as far as Endean's baked clay James, but I think we have been collecting through all the different fads in potting soil. Strange thing is the plants seem to grow in most. A friend of mine once said "you can grow cacti in anything as long as you get the watering right" meaning whatever it is, if it stays wet too long they rot. But again what potting mixture works for you can depend how hot your climate is for the plants to dry out quickly enough.

I also found that they do better in coarser mixes, putting everything over a fine screen before mixing such as a flour screen or fly screen type mesh. The only problem is when you buy the ingredients, or ready made potting soils, about quarter of what you have paid for disappears as dust.

[ElieEstephane]

But again what potting mixture works for you can depend how hot your climate is for the plants to dry out quickly enough.

Dave i think what potting mix you use also depends on the cacti you are growing. From my own experience, and there's no guarantee i'm right, opuntia and some parodia types seem to favor more organic and fine materials in the mix. Wirh my oreocerei, I used my regular of 70% grit and 30% composted materials and they weren't growing as squat as they should due to the soil being too rich. Aloes, haworthias and echeverias seem to be doing terribly in the same mix growing very well but with leaves always curled and not very juicy.
Of course any mix that dries out quickly is generally good for any cactus, but if one has the time and patience, the mix should be tweaked according to each genus and species or optimum results.