London (change)
16 messages
06/05/2012 at 21:30

Hello All, I'm in my first season of using a greenhouse and to get me started I ordered a lot of bulbs which I happily potted up in B&Q multipurpose compost.  I had long black trays with matting in them and put some grit on top then stood my pots on the grit.  I thought the idea was that the plant roots would reach down to get the moisture therefore, grow good strong roots.  I can only get to garden at the weekends so I thought this would be a good idea to ensure there is water through the week, that said, I don't drench them at the weekend, they only looked like they needed one water over the weekend but I did put 'a little' water in the tray - just enough to reach all pots but not that you would see it under the grit.  Problem is - on checking the soil lately (things should be growing by now), a lot of the pots are surprisingly wet to the touch.  I tipped one out today to find a rotten dahlia bulb and am worried about the rest but don't want to tip them out unless I have to.  What have I done wrong?  Do I tip the rest  or see what happens?   

06/05/2012 at 21:42

Your problem is ;-

You've choosen the wrong method of watering. This method works best for potted plants. Tip them all out and see if any have survived.

Bulbs only need moist compost/soil. They probably only needed a drink once a week/fortnight in cool weather.

We live and learn.

06/05/2012 at 21:48


Simply too wet, too cold-there has not been enough sunshine to warm the greenhouse naturally.

I too would tip them out to see if there is anything growing.-sorry.

06/05/2012 at 22:14

oooowwwwww - I thought you were going to say that.  Thank you for replying.  So if I'm planting bulbs I don't have to sit them in anything, the pot can just sit on the shelf.  Well that's a good GH lesson learnt.  Am I doing the right thing with the matting and the grit - watering the grit rather than the plant, or a bit of both?  

06/05/2012 at 22:33

What you want to achieve is a system where the roots can breathe -having the pots sitting in water for any length of time will just cause them to rot-I don't think the matting/grit thing is ideal

Visiting the greenhouse once a week in Summer is going to cause you a lot of disappointment I feel -you are going to have to employ a recruit to look after things if you can't yourself-of course I don't know your circumstances

07/05/2012 at 04:58

Ideally you will need to visit your greenhouse for a few minutes each day in Summer - to open  the door and windows for good air circulation and to bring the temperature down as a greenhouse can get VERY hot ! I wet the path down with water in the mornings on very warm days as this also helps keep the temperature down and deters red spider mite which can be a problem in hot dry conditions.I have invested in a Max/Min thermometer which tells me the lowest and highest temperature in the greenhouse. As Geoff says the trays with matting would be good for potted plants with a good root system and will also help with the humidity. I feel like I have given you a lecture - sorry- It is just that I am a very keen greenhouse gardener

Pam x

My pot plant greenhouse last Summer

07/05/2012 at 09:37

Thank you both very much, I work away in the week which is a pain and Pam it didn't sound like a lecture but I'm up for it every time - not gonna learn otherwise

I have an auto window opener but I expect that's good but not good enough.  I have bubble wrap still on the back and side of the GH which are both up against fencing  and I've been looking at green GH shading (it's quite thick) and to me I can't see the point of shutting the sun out but probably by next year I'll have changed my mind??  Should I get the shading and does it go everywhere? It's only a 6x4 GH and I quite like the idea of being able to see in it at the mo, my garden is only about 30'x30'.

As soon as the weather is good I plan to plant a lot of the bulbs out (the ones that have produced!) then use it mainly for veg and bringing seeds on.

Great picture 

07/05/2012 at 09:48

Sun through glass can damage plants and if it gets to hot they will stop growing-hence the need for shading to keep the temperature down-sound a bit peverse but the light can still get through.

You can buy shading paint that goes clear in the rain.

Depending on where the greenhouse is situated dictates if you need to shade all over -does it get sun all day?

I would remove the bubble wrap it is not need at this time of year.

Just a pedantry note-forgive me-dahlias are not bulbs but tubers-there is a difference

07/05/2012 at 10:33

Thank you - and you are forgiven  I bought a varied collection with a bit of everything in it.  All I know is that there is a difference in shape and tubers should be dug up, dried off and overwintered whereas bulbs can stay in the ground.  I need to get my head in the books.  

GH is on the East side of a North facing garden (facing West) so as you look at it the back and left side are up against fencing so I only need to really worry about the front and side I think.  As much as I don't like the sound of it I think I'll put the shading material inside rather than paint outside. Because I'm looking at it all the time I want it to look relatively tidy otherwise my OCD will kick in

07/05/2012 at 10:47

Shading material goes on the outside-a cheap alternative is watered down white emulsion-

(but I don't think you are going to like that)

07/05/2012 at 11:05

errr, you are correct  I'll definately look into it, thank you.

07/05/2012 at 14:15

You will need to shade in some form - it is amazing how hot it can get ! I have 3 greenhouses and shade each one a bit differently - I use Coolglass which is painted on like Geoff says. My pot plant greenhouse is shaded all over,my veggie greenhouse is just shaded at the end where I grow cucumbers and my other greenhouse is shaded on the roof and one side.I am retired so can visit them often!

I am really worried that your greenhouse won't get any attention during the week - what exactly would you like to grow? Maybe I can help to sort you out a plan of action

Pam x

07/05/2012 at 15:15

Ventilation is so, so important in a greenhouse. With still moist air, mould can quickly start. My greenhouse roof vent and door remain open almost twelve months of the year and only closed in extremely windy or freezing weather.

07/05/2012 at 16:33

Pam - a plan of action, that sounds like fun to me.

Thanks Paul, Interesting about the door being left open, no reason why I can't do that.  I have found a bit of mould before and now I know why 

I've attached an old pic above taken a few months ago after the GH was put in.  The one below is now, with the addition of some  home made raised beds - ready for veg. It's still a work in progress but it's getting there.

 You can see where the shade falls most of the time and it closes in over the garden later in the day.

It's full of all sorts right now and probably will be in the future as I want to grow flowers and veg - veg need more room so I may well give into them over the summer and raise cuttings etc over winter - just don't know yet, I'm learning as I go.  I may have to take out the potting table on the left to make room for tomatoes??

See - told you it was small.  There's not much floor to water after I've finished in there! 

07/05/2012 at 16:45

You are doing well-and there are people on here that will talk you through any worries.

Just one word of caution about leaving the door open 24 hours if you are not there to look after things-you don't want a cat or fox in there causing mischief-rig up some sort of barrier -perhaps a piece of wood-I use an old stair gate wedged in.

07/05/2012 at 17:30

Good point - I've some netting that I can attach over the full length of the door.  I'll set that up next weekend.  I have a cat who loves to sit in the GH all day but she wouldn't appreciate any visitors. Thank you.

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