Greenhouse v polytunnel

rockat man

I currently have a fairly large polytunnel (40 foot long by 25 foot wide). This is my third year having it. All the summers have been very poor since I got it - this year probably the worst! In the first 2 years I had a lot of problems with grey mould - 1st year I had too much in it and I was keeping the doors shut to try and ripen tomatoes etc but this caused more problems with mould and disease. This year I have less in the polytunnel - I have a good few tomato plants, cucumbers, a few sweetcorn and melons which started setting fruit a few weeks ago so I am hopeful of some melons next month! I find the polytunnel great for early vegetables - we had some new potatoes in May this year and strawberries as well. I currently leave the doors open day and night to help with ventilation as there are some black spots coming on the tomato plants which I cut away as I see them. If I leave the tunnel closed even at night, there is a lot of condensation on the inside which then drips down during the day. If we were getting some good sunny days, the sun would burn this off early in the morning and it wouldn't be a problem but on these damp and wet days, the condensation does not dry off and if you close the doors again, the conditions in the tunnel get damper. By leaving the doors open, I am finding that it is quite cool in the tunnel and growth is not what it should be. Melons and cucumbers like warmer conditions than tomatoes and I am considering purchasing a greenhouse as an alternative for these. Just wondering does anyone have a polycarbonate greenhouse and is condensation or dampness an issue with these? I was looking at a Gardman one on the net and it seems good value. I am considering the polycarbonate because we get a fair bit of wind and have kids so I think the polycarbonate is a bit stronger than glass. I am also thinking of purchasing an electric propogator and putting some electric in the greenhouse and using the propogator in the greenhouse as I find there is not enough light if I try to propogate indoors and plants get very leggy. Below is the link of the greenhouse I am thinking of purchasing. I asked about postage to ROI and was told £4.95 same as for UK.

http://www.primrose.co.uk/greenhouse-type-greenhouses-freestanding-c-696_3595_3746.html?src=cbtype

redser7

I have green mesh over my door panels and plastic covered panels which sit into the frame for when it is cold. I take the plastic panels out and leave them out all summer with just the green mesh on. Have no problem with condensation that way. There is always good airflow, but not too much and pests cant get in as easily. So long as night temps stay above 10 degrees outside that should be fine. Toms, peppers, chillis, cucumbers etc all doing well. So think about modifing your doors. I use soaker hoses too which keeps most of the soil surface dry, except immediately under the hoses where the water weeps. That way there is less water around to evaporate. I also mulch the soil surface with grass clippings which stops evaporation too. Dont know anything about greenhouse personally.
Poor weather in the last few years so don't write off the tunnel on that account.

Begs

I took over a similar sized tunnel this year and have had no problems with mould, etc, so far... no doubt that will change immediately on typing this! This is probably down to the fact that there is some 'natural' ventilation via various holes and also that the doors are by no means air tight!

One thing that I did invest in which may help you was greenhouse roof vents. I attached these to the window openings above the doors at each end of the polytunnel - they were €25 each off ebay and I think manufactured by Bayliss. These have helped keep the temperature down at a constant level and added some bit of airflow. I would not guarantee that they replace daily opening of the doors to let air flow through.

The next thing that I want to 'automate' is the watering. Have you tried adding an automatic irrigation system - hozelock or other? I have pondered buying a small kit and testing it out but have now seen the aquapods and think that their adaptability may also be useful when growing veg in different areas each year. I then thought I should try both but am unsure if the two systems are compatable? Any thoughts on what to do or try?

redser7

I forgot to add that I have a permenent mesh covered vent above the door lintels on both ends. These are open all year round. Temps drop anyway so it doesnt make a difference. Ventilation in tunnels is more important than sealing them up completely I find.

Here's mine so you can see the how I did it ...
http://www.boards.ie/vbulletin/showthread.php?t=2056374212

I see lots of tunnels/greenhouse at the plots and they are permenently streaming with condensation because of lack of airflow.

I automated the watering with a gravity fed system. I use a 1000 lt IBC tank connected to an Aldi water timer, which in turn is connected to a soaker house (Lidl) which snakes round the beds. Important that you create a loop so the water pressure is equal all along the hose. Again Lidl were selling hose connectors and I got a splitter. So one end of the hose is connected to one spout and the other end returns to the other one creating a circuit. I set it up in early June and apart from when I feed the plants I havn't watered once. Couldn't be happier. Everything is doing fine and setup was cheap as chips so no need to go for expensive store bought systems.

Cardinal Richelieu

I have a greenhouse, even with a greenhouse you will have condensation and Botrytis problems. The best way is to try to change the environment that grey mould thrives in so try to regulate watering depending on the weather outside, improve ventilation and practice good hygiene to prevent the spread of disease.

Oldtree

The polytunnel hasnt been what it used to be, for example I used to get temps of over 40 degrees easy on a hot day in the summer a few years back but last year it didnt go above 20 all summer. This year has been slightly better but as all my first set of seedlings died off I had a very late start with the tomatoes still green at the mo. Doors off all summer for good ventilation but real problem as as gets damper trying to keep the heat up, difficult balance.

polytunnels aren't frost free so I made a frost fleece klosh on a bench in the tunnel for stronger potted seedlings started indoors.

I dont use a timed irrigation system any more as the batteries failed at one time when I was relying on it and the place was flooded out as it failed in the on position.

neighbours have had great heat in glasshouses this year and good early crops too.

redser7

I read that about the timers alright. But they do say to watch the battery indicator and change them once the low symbol shows up. How come the tunnel isn't heating as well anymore? Is the plastic dirty maybe?

Begs

I recently cleaned a few of the dirtier panels. Two bits of string, a big sheet, water, some washing up liquid-and a lot of shouting and they were cleaned in no time. Surprisingly a lot of the dirt is on the inside.

I think that I'll give the aquapod watering system a go - whilst they dont cover a huge area, I like the fact that they can be moved around the place when required.

Oldtree

cleaned the poly regularly as there is a problem with aphid sap, we just havnt got the lighter brighter days here that we used to get in abundence.

redser7

Very true, dismal summer

rockat man

Thanks for all the replies. Redser I saw your tunnel when you originally posted the pics and I must say it is fairly impressive. I'm afraid DIY is not my forte. At the start of year 2, I did put netting on the top half of both doors and also have these plastic attachments similar to yours which I attached at night earlier in the year and put on last week when there was high wind forecasted. While these do let in some air, they do not seem to let in enough. I have attached some pics below. As you can see, there is not much room above the door although I may think about taking out the top piece of timber and replacing it with two thinner pieces with wire netting in the middle. I think the wire like you have is probably better as it will let in some bumble bees which are good for pollination. I had some trouble pollinating melons earlier this summer but read on the net that they should be pollinated in the middle of the day. I tried this and it seemed to work (or else the bees did the job) as I have melons now.

On the watering, I did install a drip hose in the tunnel but found that the watering was uneven. It would water a lot for the first initial piece of piping and you would get some spraying with caused puddles on the paths etc (probably too much pressure). I then split the hoses in half to have 2 separate hoses on each side of the tunnel and this seemed to help. I would have used the drip hose earlier in the year when I had potatoes and cauliflower/spring cabbage etc. I got 2 water butts this year and with all the rain this summer, I have been using these for my tomato plants etc as I think the rain water is better. There is a good bit of chlorine in our water. I have a hose running into the tunnel and water using a watering can as I use a half strength tomato feed as some of my tomatoes are in containers this year with mixed success. By using the watering can, I can keep the areas I don't want to water dry. Some of the tomatoes in containers did great initially but then seemed to die off. I have Liliano tomatoes in tomato planters which did great. They were recommended by Suttons as blight resistant and I am getting a great lot of fruit from them. Will post more pics below.

rockat man

More pics below. As you can see the tunnel floor is very dry. I didn't bother with any raised beds as I like to be able to rotate my potatoes from one side of the tunnel to the other each year.

I cut away any diseased leaves but when it gets on the stem or on the fruit stem, its hard to know what to do with it. I had one tomato plant near the front door and I found some brown mildew on the bottom of the plant which was squashy when you felt it and when I saw the top of the plant drooping, I pulled the plant out. This was mid July. I was afraid it was blight as I had some blight on my potatoes outside.

The Liliano tomato plants are a big success. They are a bush variety and I have them at the sides of the tunnel. They take up a good bit of space though. The branches droop over the sides of the planter and its only when you lift them back, that you see the amount of fruit. I tried hundreds and thousands last year in the ground and they didn't do well at all. A lot of the blossoms just fell off. With the Liliano, I am getting a lot of fruit.

I also tried some tomatoes in hanging baskets this year. They are a cone type of basket. The baskets had plastic liners in them which I thought would be great for conserving moisture. The instructions said to put sand in the bottom but as I didn't have any, I just put in compost. After a few weeks, the plants (Maskota) started to turn yellow and loose some leaves. I read on the net that they need drainage so I pulled the plants out of the baskets, put holes in the plastic and settled them in again. I did get some early tomatoes from them (mid July which is a few weeks earlier than I would have gotten them in the past) but the plants have died back a good bit now (similar to some of the plants in the plastic containers), although I see some of them are producing flowers again. The other mistake I made with the hanging baskets was I overfilled in the compost so they were a disaster to try and water as the water kept running off. With the holes in the plastic now, when I water them, the water runs though after a bit onto the polytunnel floor. Does anyone have any experience with tomatoes in hanging baskets? I have a pic of the baskets in my last post.

rockat man

Some more pics below.

The large tomatoes are only starting to ripen now. The Big Boy are huge. I like a lot of big tomatoes for making tomato soup. The chilli peppers are only startin to come now. I had these in pots and transplanted into the ground in June when my early potatoes were finished but it took them a few weeks to start growing again. I think they may have been better left in the pots. I think peppers need more heat and I thought they might do better in a greenhouse.

Hoping to get some melons this year if we have a good September! Can't be any worse than June, July & August. I tried melons in the past. Brought home a packet from holidays but they must not have been suitable for our climate because I only ended up with one the size of a large grape in October when cleaning out the tunnel. This year, i tried 3 varieties. Emir, Sweetheart and Outdoor Wonder. All 3 are doing well. Sweetheart is the one recommended to do well in England/Ireland. I have melons on the Emir and Sweetheart so am hopeful of some fruit this month. The outdoor wonder are supposed to be able to grow outside but were later developing the female flowers and I don't see any polinated melons on those yet.

I think the polytunnel is great and wouldn't swap it for a greenhouse. When I was originally trying to decide on between a polytunnel and a greenhouse, I went for the polytunnel as you had a lot more space and could sow things like early potatoes which for me are probably the best thing I get out of it. I think they may be more suitable for growing veg than the tender plants such as tomatoes, peppers etc. Maybe its the weather. I often thought that if you did get a good summer, you wouldn't know what do with the amount of veg you would get out of it. I notice this year, there is a lot of blossom rot on my bigger tomatoes which is probably down to the weather. I just thought with the greenhouse you would have less condensation although per replies above, this is not the case. I would also be nervous about putting an electric propogator into a polytunnel (I know you can get special cables & connections etc). I thought it would be safer in a greenhouse. I will probably try Redser's suggestion on putting a wire vent over my 2 doors. My DIY skills will probably stretch to that.

Oldtree

Lovely tunnel, Going to change my doors as they too heavy. what did you do to prevent the wooden posts holding the door up from rotting, are yours in ground?

I put a post in the ground outside to clip the doors to when I wanted to open doors to increase ventilation.

rockat man

The guy I bought the tunnel from helped me putting it up. I dug out the trenches and erected the bars and he did the carpentry on the doors and we put on the polythene together. Wood holding up doors is fine so far. Plastic is wrapped around them and pinned on the inside so maybe that is keeping them good.

redser7

Looks like a great setup there! Look I'm no expert On the water pressure in the hoses, you need to create a circuit to get even pressure all along the whole length of the hose like I mentioned above. Soaker hoses are better then leaky pipes I think because they weep rather than spurt water. They also require less pressure to work well so a water butt can work well enough if you keep it topped up. So see if you can pick up a Y junction and run each end of the hose in. It will make a big difference. I dont think those hanging baskets are big enough for a tomato plant and the conical shape might not suit the roots. Something like an 18 inch basket would probably do better. When people grow toms in pots they would usually use minimum 10 lt pots so you would want the equivalent in a hanging basket. I wonder if your toms all planted either side of the path like that are restricting the ariflow through the tunnel? Could you grow your tall stuff closer to the tunnel sides and using strings and/or canes grow them up at an angle if they reach the cover too early. Leave the shorter stuff for near the edges of the central path. It also looks like there is an abundance of foliage there. Are you nipping out the side shoots and removing tom leaves from the bottom up as they age? It all helps with airflow. Fair play getting melons!!

rockat man

Redser, I put in the vents over the doors on Saturday and closed the doors on Saturday night and full of condensation again on Sunday morning and even worse this morning so have left both doors fully open tonight as I can see more problems with mildew and some of my big tomatoes are starting to fall off with disease. Maybe I am getting more condensation than you with the bigger tunnel. I have the green netting on the tops of the doors and don't think it would help if I put it on the bottoms too. I thought the vents over the doors would help as there was a nice breeze blowing in. The other things I am thinking are type of plastic and location. I notice that some of the bigger suppliers offer different types of polythene with non drip options. The other thing I heard is that a tunnel should be facing a certain direction. I placed the tunnel about 2 feet away from the kerbing on the tarmacadam facing out into the garden so that I was stepping from the tarmacadam into the front door of my tunnel. The guy who sold it to me didn't say it should be a certain direction as when he dropped it off, I had the trenches nearly dug out. Don't ask me what direction it is, north east etc. Maybe I should have placed the tunnel in the other direction, paralel with the kerbing and I would have gotten more airflow through it. I will experiment a bit more with the hanging baskets and will try a different shape and maybe some different varieties.

I spent this evening cutting away a good bit of foliage and nipping out the tops. Some of the fruit stems on the bottoms of the plants had no fruit due to blossom rot and I was waiting for tomatoes to reach the top of the tunnel to have more fruit to make up for the bottom stems so maybe I have too much in the tunnel again this year. I always start out with the best intentions, actually disposed of some tomato plants in compost earlier this year as I had too many, had grew all from seed and did not want to have too much in the tunnel but they grow so big.

redser7

I dont think the curb or the orientation will make a significant difference. Gable ends to the prevailing SW wind I guess would help but still it shifts around and eddies a bit. Some people do the opposite so as not to risk storm winds getting in and wrecking the tunnel. So either way should be fine really, just a matter of personal choice.
My cover has anti-fog coating and indeed most tunnel covers would. Maybe if yours doesnt that could be it. But dense foliage and too close planting will stop the airflow and condensation clearing. I have a huge cape gooseberry in one corner and it is growing tight up against the gable end plastic and it is pretty damp there. So I need to prune that back. How close are your toms? They should be minimum 18 inches apart.
If you are letting them get to the top of the tunnel they might be too big. Some people do this but I guess they would have bigger tunnels/greenhouses. Most people would stop the plants at 5 or 6 trusses which would be about 5 feet high I reckon. So I think if you space stuff out, keep them less crammed, and side shoot the plants regularly it will make a big difference. And at the this time of year a lot of branches would be taken off to help deal with the oncoming damp autumn conditons. You could also try pushing your plants a bit with the watering and be a bit stingier, especially at this time of year. But try it next summer. If they start to suffer then of course up the watering again. But you might be over-watering??
This is a great book on polytunnel growing ...
http://www.amazon.co.uk/gp/offer-listing/0711231702/ref=dp_olp_used?ie=UTF8&condition=used

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