[Randybobandy]

Is it recommended to use low mold strains in greenhouses? Ive always chosen low mold strains for my outdoor but I will be running my first greenhouse this summer. I'm thinking since it will be ventilated and dry it will be all good to run regular strains but I want to know what you greenhouse guys think.

[Dkgrower]

Just have plenty off air flow and fans running all the time and you wont have any problem

HIgh temps can be a problem fore sum strains producing nanners ect so stay away from sensitive strains...

[chappie]

I used large vent fans and circulation fans and still had trouble with supposed "low mold" strains here in the PacNW. Problem is that just as flowering peaks in mid-September, the sun goes away and is replaced by constant cloud coverage and rain. Ambient humidity is 100% for days or weeks at a time. Air circulation is not enough - a heater or dehumidifier seems to be needed.

What helped immensely was to severely defoliate the plants. This goes against all indoor training to leave all possible leaf, but it did help drastically. Prune all interior branches and as many of the fan leaves as you can at the end of August. Keep pruning every day. The giant plants don't miss the leaf - they will still keep pumping out buds. Prune any molding buds immediately and don't toss them in the greenhouse, get them out of there.

I lost about 1/3rd of my crop to mold but still had lots to show for it.

[Nuggsy Bogues]

If you crowd your plants into a greenhouse to the point where it diminishes the ease of air circulation, then pruning some branches might be necessary, but if you give your plants proper space for development, there shouldn't be any need to defoliar heavily. Every leaf you take off does mean less solar energy absorbed by the plant.

Also, when you prune branches and remove big fan leaves, it leaves temporary wounds which can be an easier attack point for fungal diseases. Giving your plants room to breathe from the start would be a better option.

Also, remember that botrytis is a fungal disease which can live in the soil and infect the plant in the rootzone. The best way to fight off fungal diseases is regular applications of fungal compost or vermicompost, both in the soil and as a foliar spray. Having beneficial fungi present will help fight the harmful fungi from taking over.

Silica has also been studied a lot in commercial greenhouse growing as a means to combat mold. Adding a mineralizing agent like Azomite which contains high amounts of silica might strengthen plants and raise their immunity to fungal pathogens.

Using strains that were developed by expert breeders who know what to look for in developing plants to use for breeding will help too. I live in an extremely humid coastal climate and i've had about 15 strains over the past few years in my greenhouse. The only strain I ever had any mold on at all were seedlings from a random cross that wasn't carefully selected for future breeding. All other strains have been completely mold free.

Keep it well ventilated and work on developing a healthy soil and you'll save yourself a lot of trouble.

[dankbuds]

trainwreck - mold and mildew resistant strain
ak47 - high mold and mildew tolerance

those are the two that i know personally to be good.

alot of people by the coastline grow those due to high PM and mold issues.