Solar Greenhouse Fans

[quanglewangle]

Fans for circulation rather than ventilation

I am installing a fan for circulation rather than ventilation. I have no problem with the later - a small greenhouse and a big vent and when needed opening the door takes care of that.

Circulation is different. There are times when different parts of the space in the greenhouse are at widely different humidity levels and sometimes this occurs when you don't want to ventilate - perhaps it is cold outside or there no breeze anyway.

It is possible to have an optimum RH, say 75% but will differ depending on what you are growing, registered in an open part of the greenhouse but this doesn't mean it is not much higher in among foliage, especially on the underside of leaves, or much lower on dry sunlit compost. What is needed then is to stir the air up.

Of course the cultural methods given in this thread: lower plant density; ventilation; watering at, or close to or even beneath, ground level; and careful timing of watering will all help. I am not dissing these techniques: It's just that a fan will help even more.

[Mamzie]

I think they possibly got botrytis not blight?

That's often due to squeezing too many plants in. If you space your plants out with a good distance apart, keep your vents open and ensure you water into the ground and not the plants - I water into milk bottles sunk into the ground at regular intervals - keeps humidity down. I believe you have a better chance of them staying healthy right up until the frosts.

Sorry, I know nothing about fans...


Good info on botrytis here :

https://www.rhs.org.uk/advice/profile?pid=165

My mystery is solved - thank you Scarlet and co on this thread, I must have had botrytis not blight last 2 years. I know I overcrowd as find it very hard to discard any plants that are extras, plus by end of summer mine tend to loop de loop around the top of greenhouse. I will plan better this year now. I grow in pots in large containers for watering.

Does the disease live on pots please?

[Scarlet]

It doesn't live on pots but if you have had it twice in a row make sure you clean everything well and give the greenhouse a good wash before you start again this year. All last years decaying material should be removed.

Try not to water at night. Water first thing in the morning - you can sink bottles into your pots to stop the water going everywhere. I know people are tempted to water the plants themselves but it's best to keep the leaves as dry as possible. Remove all your cuttings from the greenhouse, as Sariss said above , take off all the decaying leaves promptly.
Leaves touching or hanging baskets that drop leaves and flower buds on plants below can also be a problem.

Some good advice here:

https://www.rhs.org.uk/advice/profile?pid=165

https://www.rhs.org.uk/advice/profile?pid=468

[Mamzie]

Ty, I water from the bottom as use large containers under the pots and the roots tend to grow into them.

Glad to finally put a finger on the problem through x

[ghexton]

GH Planning and Overcrowding

Hello,

Again thank you for all the advice. Well when you ask one question it leads you to another area, great i love it! feel like I'm learning here.

I will probs invest in few auto GH window openers then instead of solar fans.

So onto my next questions which i had already sort of thought about.Grow space planning.

I'm looking to grow for two adults and 1 baba.
GH is 6x10 Polycarb on gravel base - grow bag and pots if that helps
https://www.summergardenbuildings.co...-30201017.html

Cucumber - Start 8 seeds pick 6 plants in GH
Melon- Start 6 seeds pick 4 plants in GH
Chilli- Start mix 6 seeds grow 4 Plants in GH
Tomato- Start mix 12 seeds grow 8 Plants in GH
Peppers- Start mix 12 seeds grow 8 Plants in GH

Is this to much or to little?
Any other plants i should think about adding?

Full list of the seeds I plan to propagate below.
https://ibb.co/RDYrhxj

thanks
G

[veggiechicken]

Sounds a lot to me unless you're growing some plants on staging above other.
I work on one tomato/cucumber plant per 2' so a 10' side would have 5 -6 plants. You may get another 2 across the far end.
I've failed with melons and don't grow peppers so can't help there.

[quanglewangle]

i agree with VC - rather a lot.

Last year (my first, so take that as a warning) I grew in a 500mm by 3m bed down one side: 4 cordon tomatoes and 6 melons. Was way too crowded but worked better than I probably deserve. Both tomatoes and melons were successful on the whole. Lost two melons to botrytis but saved things by reacting quickly with drastic thinning.

On other side, on staging. grew 3 aubergine plants in 270mm pots and 3 or 4 peppers in smaller pots all stood on a sand propagator (about 500mm by 1000mm), which had been used earlier for seed raising. They were very successful.

Will do fewer chills this year - they got in the way a bit and we still have loads in the freeze.

[veggiechicken]

Another thing to think about is the growth habit of the tomatoes you intend to grow - whether they're Bush/determinate
or Vine/cordon/indeterminate.
Bush toms are shorter but denser whilst Vine toms will grow tall, to the roof, need support and regular pinching out of sideshoots.
All toms aren't equal so choose carefully and set up your supports in advance.

[quanglewangle]

Melons are pretty heavy. Make sure the structure will support them.

If you want to see what undisciplined vine tomatoes can do have a look at this

https://youtu.be/EsuaMGen1EU

I set the camera up to see the melons grow but the tomatoes had other ideas.

I will do better this year.
I will do better this year.
.
.

[rary]

Back to the fan, I keep a fan running all the time when I have plants in the greenhouse along with 8 auto vents the fan protects the plants from frost damage and the vents are supposed to protect from over heating though I have experienced higher temperatures than I would like, I do have an electric supply into the greenhouse if I didn't I think I would have vent fans and solar powered fans fitted, I have avoided both blight and botrytis

[ESBkevin]

I agree that automatic window openers are a worthy investment, takes some of the worry out of visiting the greenhouse morning, noon and night for those of us distracted with 'other 9-5 jobs' away from home.

The big thing commercial growers do to aid circulation is to strip off all redundent leaf growth, thats everything up to well set fruit on a tomato plant. Look at thier rows of stalks with ripening fruit all exposed. Also remove all plant debris so that it can't hold botrytis near the plants. Ground drip irrigation. That means there is no need to install and runexpensive devices and the harvest is easier as a by product.