Seed compost and the Quarterly

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McGregorUS
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Seed compost and the Quarterly

Every time I talk about seed composts over here in England I always talk about my basic mix as 1 part John Innes compost, 1 part sand and less than 1 part grit. Then compact that in the pot and add a layer of more sandy mix at the top, onto or into which I sow the seed. Then if the pot will go straight outside I tope off with grit.

But then I explain that I then adjust the mix by physical feel, does it scrunch up in the hand too much and so on. And then I talk about basic potting compost as using the same three parts but a full 1 part grit or even more. And I almost never use peat or peat-based composts - but then I don't really grow ericaceous plants so its not much of a problem.

But when I talk to North Americans I have to explain what John Innes compost is - basically a sterilised loam with additions of a standard recipe of additions. There are 4 standard recipes which have more additions of fertilisers from John Innes [JI] Seed, through JI 1 to JI 3.

I want to get an article on such basic things as sowing alpine/rock garden seed for the Quarterly (from someone or some two or three for that matter - feel free to volunteer) so I'm really interested in what you do - garden soil/dirt - sterilised or not - commercial or what.

And from the number of reports about early germination a whole lot of people must be keeping all their pots of seed in the kitchen or playroom or bedroom or wherever.

This year I've sown about 70 pots of seed {surplus seed just ordered} and they are all outside in a frame having been started outside to get covered initially by snow - the cover had ice on it again this morning and the average day temperature is now up to around 4oC and -1oC at night. Usually by now I would have germination but this year I'm so envious of all these great reports.

McGregorUS
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Replying to your own post might seem odd but that's only because I managed to get no replies from anyone else!

Finally we have had our first couple of days with the temperature reaching 10oC and I've had two seedlings appear. One is Dianthus superbus and the other is in a pot labelled Geissorhiza corugata. Unfortunately it is clearly not what I'm waiting for (not a monocot) but neither is it any of those in-house things which appear on their own so it's potentially interesting although not yet more than potentially.

But then I do have about 68 other pots - all in the cold frame - which I'm still looking forward to.

Malcolm McGregor
Global Moderator/NARGS Editor
East Yorkshire, UK

Hoy
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I counted my own pots yesterday - and tallied about 200! I put some outdoors in a snow heap (this year, normally we haven't snow for more than a day or three) but bring them inside after a month or two. We have only had 6oC so far and the last two days the snowy weather has returned. About 10 species have germinated, two different Helleborus and some others. One of the hellebores I sowed two years ago!

Trond
Rogaland, Norway - with cool, often rainy summers  (29C max) and mild, often rainy winters (180 cm/year)!

McGregorUS
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Quote:

I counted my own pots yesterday - and tallied about 200!

I never get that far although by the time I've finished this year I will be up to around 120. Last years could be added to this but they have moved to other places - I'll report on them sometime. Still seeing new things from last year including tulips and paeonies. Now I'm waiting for the surplus seed to arrive.

Quote:

I put some outdoors in a snow heap (this year, normally we haven't snow for more than a day or three) but bring them inside after a month or two.

That was what I did this year - three weeks under snow (never been known till this year so it was too good to miss) and then in the coldframe although the NARGS seed got cold and wet rather than the snow because it was he last to arrive.

And is your seed mix like mine?

Malcolm McGregor
Global Moderator/NARGS Editor
East Yorkshire, UK

Hoy
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My seed mix is peat-based which is common in Norway. I often mix with additional coarse sand, perlite and vermiculite. I have no standard recipe but use what I have. But I like to feel it with my fingers. I also buy "såjord" (special compost for sowing). Some of the brands can be quite good.

I have read about John Innes but we have nothing like that in Norway. Different firms use their own recipe and you can get compost with different pH, nutrient additives etc.

Trond
Rogaland, Norway - with cool, often rainy summers  (29C max) and mild, often rainy winters (180 cm/year)!

Lori S.
Title: Moderator
Joined: 2009-10-27

I tend to start some plants from seed every year as well.  I also start with so-called "soil-less potting mix" (peat-based) and mix in sand, vermiculite and perlite... no strict proportions.  The pots I use each year are the vast collection of 2 1/4" square alpine pots that I've amassed.  I never sterilize anything, nor do I even wash out the pots.  Damping off and fungal growth have never been problems.  
My seed-starting stand - which is a rough cedar frame with 4 shelves - is located in the furnace room in our basement... conveniently next to the cold room where I can also stratify those things that need it.  (I have also often used the Dr. Norm Deno baggie method for germination - very space-efficient! - with the baggies placed in the fridge for stratification, but this year, I happened to start everything in pots.  I also usually chuck some trays of pots outside to stratify, but didn't this year.)  
There is also a table with a big rectangular plastic basin for mixing soil, handling pots, writing labels, etc..  It's not actually a very big space, but it is sufficient!
Each shelf on the seed-starting stand has two 4 foot fluorescent light canopies, each with 2 bulbs.  The bulbs are regular warm white, cool white - whatever happens to be around as a replacement if one burns out!  Each shelf holds 4 commercial plastic plant trays; each tray holds 48 of the 2 1/4" black plastic alpine pots (commonly used around here).  The light canopies are suspended on chains so that they can be lowered to sit right atop the seedlings initially, then raised as the plants grow.  It seems to provide enough light to get seedlings through the 13 weeks or so that I'm usually growing them inside, before I can chuck them outside after most of the frost risk has passed.  
We did have a 1000-watt halide light system once in our basement for overwintering tropical water lilies and other tropicals - a hugely better quality of light (incredibly intense - looking at it causes retinal damage), but not pleasant things to have around.  I'm happy with fluorescent light...  

This year, I went a little out of control... I participated in the seedexes of both NARGS and SRGC, and then made substantial orders to both Pavelka and Holubec (irresistible stuff  8)).  And, as we speak, I have actually run out of pots for potting-on!  Unprecedented!   :o

Lori
Calgary, Alberta, Canada - Zone 3
-30 C to +30 C (rarely!); elevation ~1130m; annual precipitation ~40 cm

McGregorUS
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Quote:

I have also often used the Dr. Norm Deno baggie method for germination - very space-efficient! - with the baggies placed in the fridge for stratification, but this year, I happened to start everything in pots.  I also usually chuck some trays of pots outside to stratify, but didn't this year.

I cdertainly found this approach - sowing in the fridge - invaluable for saxifrages from Magadan in Far Eastern Russia (Alexandra Berkutenko seed). Sprinkling the seeds on damp paper towels, then folded over and kept in bags in fridge. Checking for germination and moving on as germination occurred.

You both (Hoy and Skulski) say that you use peat and mix in sand, perlite and vermiculite - and you have no strict recipe. But do you think the mix is roughly 50% peat by the time you finish or less than that?

Malcolm McGregor
Global Moderator/NARGS Editor
East Yorkshire, UK

Lori S.
Title: Moderator
Joined: 2009-10-27

McGregor wrote:

You both (Hoy and Skulski) say that you use peat and mix in sand, perlite and vermiculite - and you have no strict recipe. But do you think the mix is roughly 50% peat by the time you finish or less than that?

The "soil-less" mix which I use is composted peat... it can look very peat-like when it dries out, though it also varies fairly significantly in appearance from bag to bag from different suppliers.  Volume-wise, I suppose my mix is still at least 50%* composted peat at the end.

* Acckk!  I've edited this 2 or 3 times now; I think it finally says what I mean it to!

Lori
Calgary, Alberta, Canada - Zone 3
-30 C to +30 C (rarely!); elevation ~1130m; annual precipitation ~40 cm

McGregorUS
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I always find problems with peat-based composts. The main one here is that they can dry out too much - living in a low-rainfall area (less than 24 inches a year) means that they can dry right out and surely that's a particular problem with seeds and seedlings. Do you water a lot, keep them under cover, or what .....

Malcolm McGregor
Global Moderator/NARGS Editor
East Yorkshire, UK

Lori S.
Title: Moderator
Joined: 2009-10-27

The pots are kept under clear plastic covers (covers that fit the 48-pot seed trays are readily available) until germination, then pots are moved out from under the cover.   I give them a dribble of water daily while the pots are indoors.  When they are later put outdoors for hardening off and as they are awaiting planting, they are also watered daily... but regular plants with large root runs that are planted in pots with humousy/peaty/compost soil, regardless of pot size, must be watered daily outdoors here for best results.   (This doesn't apply to troughs, however.)

I need to review the definition of "loam" and of John Innes mixture and the variations thereon!

Further:
"Loam":  40% sand, 40% silt, and 20% clay?  

Lori
Calgary, Alberta, Canada - Zone 3
-30 C to +30 C (rarely!); elevation ~1130m; annual precipitation ~40 cm

McGregorUS
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The big difference is that instead of your peat-based mix I'm using a soil-based mix so that doesn't dry out in the same way (and they are kept in a fairly shady area) but I spend time in the spring and early summer trying to make sure they don't dry out too much but I wouldn't water as often as you by the sound of it. Once they have germinated and have got started I want them to adapt to the local conditions so I don't water any more than I absolutely have to.

And troughs only get watered in very dry conditions - although I have to say that we do often get very dry conditions! The approach with them is to have a lot of rock across the surface so that there evaporation is cut right down.

Malcolm McGregor
Global Moderator/NARGS Editor
East Yorkshire, UK

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