Moss and liverwort

[Palustris]

Not sure if this goes here or Growing from Seed, but here goes. I have a fair number of pots of Roscoea seedlings. However all of them are infested with moss and liverwort. The seedlings are getting to the size where they desperately need pricking out and growing on. Has anyone any advice on how to get them out of the moss. Just tried and the roots are so entangled with the stuff it is almost impossible to get them out undamaged.
Frustrating!

[Maggi Young]

Ian suggests waiting till they are dormant to be able to separate them from the  moss etc.  The moss and liverwort will be less of a problem then.

 If they need  more space/feed now, then pot them on en masse to give them a boost.

[Palustris]

Thanks. I had a feeling that would be the advice. Finding bigger, deeper pots is a bit of a problem though. Better than losing the seedlings though.

[SusanS]

When you repot it could be worth trying a different growing media.  At nursery we use Melcourt compost, this is moisture retentive but very free draining and the surface dries quickly which should discourage liverwort and moss growth.   For the most part it works well and there certainly is a lot less surface growth than we have had with other growing media.  It is important however to fill the pots right to the top, if the pots are only part filled then the liverwort establishes itself and grows vigorously.

The physical properties of the product mean that when you are potting with it you must not over compact it, we find that a light firming around the plant (rather than forceable pressing) and a couple of taps on the bench is the best approach.

We use it successfully for a wide range of plants including Roscoea, the only thing that doesn't seem to like it is Aquilegia. 

One thing I would say is that because the product isn't sterilised it can sometimes produce fruiting bodies of fungi.  Also as it is free draining you may need to alter your watering / feeding regime.

Susan

[Palustris]

Thanks for that. Is the Melcourt compost a peat free one?

[Sally]

A light coat of grit over the media surface discourages moss and liverworts. It is widely used in reforestation nurseries in this region and I use it on any pots or trays of seeds sown.  Discourage is the operative word here; eliminating the problem completely isn't always possible.

Sally
South of Lewiston, Idaho, Zone 5ish

[Sally]

Perhaps I should've been more specific since most growers grit their pots. I think a very sharp grit is best. Any moisture drains right through it and it doesn't pack so discourages any footholds by the liverworts. I use a regular forestry grit. I don't know what it would be called in other countries.

Sally

[Palustris]

All my seed pots have a deep layer of fine grit (3mm. crushed granite) and it does not stop the moss and liverwort at all. Even watering with tap water rather than rain (as recommended by someone) has little effect, nor does Cider vinegar.

[Sally]

My sympathy! It's such a frustrating problem. I hope someone offers a viable solution.

Sally

[Darren]

Thanks for that. Is the Melcourt compost a peat free one?

It is peat-free yes. Entirely bark-based.   I use it for Roscoea and also for Trillium etc. No moss or liverwort problems.

[Palustris]

Thanks. Now I have to find somewhere local which sells it.
I do use a peat free compost, but still get problems with that as well. However that is not bark based, rather sterilised garden waste.

[Rick R.]

Of course, vinegar would not kill moss, and I have heard before that for some people it doesn't kill liverworts, either, although vinegar does a great job killing liverworts for me.  There must be different types that are resistant. 

For me it is keeping the spores from germinating with light on a moisture retentive surface.  If I have a 8-10mm deep, clean grit layer (3-5mm size grit), I never have a problem. But even a little bit of soil with the grit, that defeats the purpose, and then liverworts can grow.  (If, for instance, I pull out a weed in the grit without being careful not to disturb the grit layer.)  The grit needs to stay clean.  Does the pH of the grit matter? I don't know.  I use a granite/quartz grit that is locally processed here.