Make sure the compost in the pots isn't sodden all the time, increase ventilation in the greenhouse, use tap water for watering, not rainwater.

I agree with Bamboo and to get rid of what is there now just scrape it off with an old dinner fork.

Tip; I keep one of these useful tools in the greenhouse just for occasions like this.

Also top off your pots with a thin layer of grit.

Yep! I agree Moon.

Having said that, I only top up permanently potted plants with grit, see no point in doing this to pots that are going to be emptied/planted out soon after the moss has been removed.

I do it with all my indoor plants as I also find it helps to keep fungus fly (Sciarid fly ) at bay.

Yes that it true Tg our plants in pots tend to be in them permanently either because they are not suitable for the great outdoors or because they are our show plants.

For troublesome moss/liverwort in pots this can be used

http://www.armillatox.com/

check out tips on the left hand side.

The armillatox will get rid of the moss/liverwort but will not address the underlying reason why it is there in the first place which Bamboo and Teegee's comments do address.

But it is there, hence my additional answer.

It's not always possible to increase ventilation unless you have a fan, which needs electricity, which as you've pointed out before, most people don't have. You can't just open the door or a roof vent and expect air to circulate nicely.

Topping off your pots with grit is a bit ludicrous, especially when you try to pot on.

This year has been a bad year i think for moss in pots. I'm putting it down to being cold and damp, meaning plants aren't growing as fast and thus water is remaining in the compost more than usual.All my early plants have had moss. But as Teegee says, scrape it off before potting on.

Cold and damp, that's for sure, I'm surprised moss hasn't started growing on me, never mind plant pots... its' certainly growing on the window trims of my car I noticed the other day...

Scrumpygal yes the moss is there but, only because the conditions allow it to be i.e. the compost being too wet, lack of ventilation and watering with rainwater.

I would never suggest using any form of fan - Bulba removes panes from our greenhouse to ensure sufficient air circulation.

Topping of pots with grit is ludicrous why? You can easily tip the grit off before you pot on - we do so regularly!

We all need to water our pots according to the weather... and it helps if you only water from below.

Funnily enough all my pots are on a capillary mat, so that discounts one theory. And funnily enough again, i've never ever used rainwater.

Now removing panels to let in the cold air is a wonderful idea. Unless of course you grow alpines. Though i'm sure that idea will go down well with local glazier companies.

Tipping off grit. Well if you have 3 or 4 plants on the go then maybe. If you have several hundred it would become a slight nuisance.

I think your solutions,ie, removing glass panels, no matter how well intentioned, to the average person are pretty impractical.

Have you got the hump scrumpygraham? Only it sounds like you have.... Seems to me if you want to use chemicals to control the problem, thats your choice - but if other people don't agree that's the right approach, that's their choice. You'll have to agree to disagree rather than get grumpy, life's too short, as the passing of Jonathan Hales today, a member of this site, proves.

Thank you Bamboo I am happy for you to use chemicals if that is your choice Scrumpy! I would point out though that we DO grow alpines, in fact they are what takes up most of the space on our greenhouse, hence the need to let the air in!

So saddened to know, at least about Jonathan Hales... He was an example to us all shouldering on through all his pain and problems! Never once did I hear him complain on GoY.

I think Mr Bamboo and Mrs Moon should read what the question was before accusing anyone of having the hump.

All i did was answer the question, which to remind you, was how to get rid of moss, not prevent it.

I don't think i've once mentioned that i've actually used it. I stated I scraped it off.

Now if people want to change the subject and go on about prevention then that's fine. Only come up with some sensible ideas. Moon.G removing glass panels is a joke.
Perhaps we could have a less drastic method from Bamboo?

Why is removing glass panes a joke Bulba takes them out in April every year and puts them back in autumn. Our small greenhouse that only has bulbs in it has no glass in the one end only mesh to keep livestock of all types out.

Oh and Bamboo is a Mrs!

I don't bother with adding grit to my pots, Moss grows on that too. I just have to scrape it off and replace with fresh compost. But at my altitude and climate it's something I have to do regularly from about feb to If and when it gets really warm.
I don't have a greenhouse, but I do have polytunnels so there is the underlying prob, although they get plenty of ventilation but still the moss. It's one of the hazards of growing in pots.

Moss appeared in pots early March. Ventilation was needed well before removing panes in April. Whats the point of keeping a greenhouse frost free if you are removing the very thing that keeps frost out. Unless you are of course growing only alpines. Like i said, for people raising normal plants you cannot keep removing and replacing panels on a daily basis which you would have to do. Pretty obvious i'd have thought.
Apologies to Bamboo, i'll await her method of ventilation.

We are only growing alpines I thought I had made that clear Scrumpygraham and this year Bulba removed the glass in March as it was so hot...

Scrumpyg - mine is the first answer on this thread, and there are 4 things listed to do to remedy the situation. As for you having the 'hump', its not an accusation, its simply a gentle observation - that's how you're coming across. I'm sure no offence was intended by anyone, and it is possible to deal with one's own offended feelings with humour rather than biting back. Never mind, some of us are more irritable or sensitive than others, and not least me, I lose patience. All seems a bit unimportant when you hear about someone dying, frankly...

Yes, yours is the first answer but you didn't answer the question. The moss was already there.

Moongrower still hasn't provided a sensible answer unless you are growing alpine tomatoes, alpine marigolds, alpine cucumbers, that would thrive on the freezing cold nights due to no glass in the greenhouse.

All I want is a practical method from somebody to improve ventilation so that your suggestion as to preventing moss can be carried out.

Actually, i think this thread is quite humorous, for obvious reasons. I'm no spring chicken myself, but the thoughts of people struggling with removing and replacing glass panels is to me quite hilarious and would make a marvellous topic for a gardeners world episode. The programme could be sponsored by elastoplast.

Bulba has only cut his finger once! If you have all these wonderful not alpines growing I would suggest opening up all the vents in the greenhouse during the day and closing them at night. Umm I thought Bamboo's answer was very clear aside from the ventilation part. Too many gardeners keep their greenhouse shut up tight all the time and then wonder why they have a problem with moss. And, no, I am not suggesting this is what you do Scrumpy.

Scrumpyg: I thought it was a no brainer to scrape off the surface of the compost to remove it, so didn't mention it - Teegee though (2nd response) did deal with that.

As i mentioned before, opening roof vents and the door does very little for ventilation. It lets heat out, but unless a strong wind is blowing outside then little will get into the greenhouse to replace the air that is already there. My vents and door are open either fully or partly, unless night and day frosts are forecast, throughout the winter. I have heat, i have capillary mats,soil warming cables, I have artificial lights.....things i would not expect everyone to have as i am growing plants optimally for exhibition.....and still from early March onwards I had moss in all my pots. Actually, thinking back, my onions had moss in February, but that sorted itself out on potting on.
So there has to be more to it than ventilation.
And watering.

As to being a no brainer, it's obviously not to the person asking the question. A lot of questions asked seem trivial to those of us who know the answers. What is simple to us is not to others which is why when i answer any question i try to answer it fully, and practically.
When others come up with an answer that is stating the obvious, but not giving a way to overcome it, then i'll question that answer for the benefits of all. Hence this ventilation business. A solution that is exclusive to alpine growers is of little use to the majority that don't grow them. So it's pointless saying improve circulation when you can't.
Unless you install an extractor fan that is.

I think the whole point has been missed and that is the" compost" itself!

This is becoming a more common occurrence since the compost recipes have been changed i.e. peat free and peat reduced composts.

Most compost are also sand free now, so this is interfering with the drainage, in fact it most of these new recipes drainage is virtually non existent, and this coupled with heat, is creating the ideal conditions for moss formation.

Moon won't have the problem as much as say myself because she needs a well drained gritty compost for her alpines.

I am finding that adding either silver or sharp sand at about six to one helps the situation and I don't have to use my fork so often if ever.

So that's my tuppence ha'porth for what it is worth.....Tg

You ar e right Tg we use a well drained gritty compost. Most alpines need a water retentive, free draining compost which sounds like an oxymoron but isn't!

The composts I use are either traditional 100% peat based composts, or the same mixed with John Innes no2. Same as i've always used but never had as much moss as this year.
I'll contact the manufacturer for his thoughts.

Try mixing some grit in with your compost!

I must admit, this year I'm mixing Levington's John Innes with the rubbish that passes for multi purpose these days, just for general potting, never mind in a greenhouse. But moss problems are rife this year, as much as anything due to the awful weather - people are having to keep plants in greenhouses/cold frames for longer. I've just put the heating on indoors not to be warm, but to take the moisture out of the air in here - it feels clammy with it. Raining again, inevitably...

I agree Bamboo I have re-christened the current lot of multi purpose composts we are getting to;

" not fit for purpose" compost!

Or multi useless compost...

didnt mean to start a war of words,but advice was all good thanx again,put me off the site a bit now though. x

"Try mixing some grit in with your compost!"

When i grow alpine dahlias next year i most certainly will.

Stevessss I'm sorry you have got caught in the cross fire - we often forget that the original questioner does not know us and our responses can come over in a way that is not necessarily intended. I do hope you will stick with the site as there is a lot of useful info. Mind you in this case things have got rather more heated than I would have desired!

How can things get heated in glass free greenhouses ?

Stevesss - don't take it seriously, sometimes some people have a shorter leash than others, but its not that often, and it's certainly not your fault - harmony reigns 90% of the time...

So sorry to hear about Jonathan and I can see what you meant in an earlier comment Bamboo

Annella - Jonathan is still alive, in fact - now listed as Jonah13...

Thanks Bamboo, that shocked me last night so I was glad to see his pic this morning :o))

Nothing to the shock I got when I received a PM from him telling me he was deceased, passed away... If you've not seen it, read my question titled 'Has Anyone Else Had a message from Jonathan Hales' posted a couple of days ago.

I tracked back and read it first thing this morning Bamboo.

I hope and trust his traveal will end soon…