At current count, I have about ten trays of seedlings, and individual pots (2″) numbering around 160. I had a stretch of time late last year where my seedling mix was apparently off, and several trays struggled – including seedlings I up-potted during that time. Some flourished, some struggled, 2 or 3 died…. which is crushing, even if it’s a tiny sliver viewed as a percentage.
Still, it means I need to keep better track of what I’m doing at each step – including the exact composition of soil mixes. Right now I’m focusing especially on the “step up” stage between 1 year and 2 years when they move from their small seedling pots to a larger, taller, “adult” pot.
… but let’s start at the beginning – germination and the first 0 – 12 months.
My seedling mix has been a slowly evolving mix based originally on Gerhard Marx’s formula:
- 1 part peat (or organic component)
- 1/2 part quartz sand
- 1 part vermiculite
- 1 part perlite
- 1/2 part pumice
The newest adjustment is to use less sand and substitute half the amount with pumice, now that I am able to reliably source online from General Pumice Products.
I use that in my starter trays – lately with a top dressing of turface, crushed granite (chick grit), or “fine sand” (very small pebbles). The trays themselves are generally foil “mini loaf pans” from the dollar or grocery store – with holes poked in the bottom with a nail, and the clear plastic covers kept on for humidity until germination. The thing I love most (beyond the low price) is that once I fill them with seedling mix, I can bake the mix directly in the tray to sterilize everything before sowing and sealing.
In stage 2 – generally anywhere from a few months to 1 year later, depending on size, I move to 2″ pots with the same mix, until they start to crowd over the edges.
At this point, I’ve been 2.7″ tall pots from Amazon from a company called BangQiao. They’ve been working great for me; but the question here is to start to adjust from a less dense mix to more of an adult formulation. I don’t want to shock root systems by a dramatic change to a system that runs a lot drier, but given that these pots are taller, I need to make sure the drainage is quick.
So my new formulation for an inbetween “staging mix” tries to take the best parts of Al’s Gritty Mix and the seedling formula. The new mix is:
- 1 part – fresh seedling mix (from a mixed container of the recipe used above)
- 1 part – more peat (usually bagged Cactus and Succulent Soil)
- 1/2 part – turface
- 1/2 part – coconut fiber
(The cheapest source I’ve found is at Menards in the spring, sold in compressed brick form as an “organic soilless seedling medium”)
- 1 part – pumice
- 1/2 part – pine bark
(I talk about sources for this in my post on Al’s Gritty Mix, but right now I have sifted and rinsed chips in a bucket that I bought as bagged mulch — just make sure it’s not chemically treated if you buy bark mulch)
The trick with this is that you want to make sure you keep your mix stirred and evenly sorted as you fill your pots; but done correctly it looks very similar to Al’s Gritty Mix.
If I find this dries too quickly still, I may adjust the composition to include more turface – since the temporary retention and slow release of water is the primary function of the turface in the mixture.
Later on, for varities that are quick growing, rapidly clumping, or just large – I upgrade them to the BangQiao 3.9″ pots – which are the same height but give a bit more room to spread out. I personally am in love with square pots, and in these particular sizes there are a few arrangements I can use to fit perfectly on plastic lunch trays I use as a drip trays and for easy slide in/out of my light growing shelves. In general the tessellation works very nicely.
In other news:
- Some of my first hybrids have started showing signs of flower spikes, so I may be about able to start on generation 2 hybrids. Some of my original home hybrids are also growing fast enough they are already started to produce small offsets.
- Thanks to a generous gift from some of my social groups, I’m experimenting with growing adeniums from seeds. After doing mostly Haworthia for two years, it’s amazing how fast these go!
Until next time!