Wondering why my plants don't like my greenhouse

[missiboswell]

Hi,

I am hoping someone can help me. I have had a couple situations with my greenhouse. I bought it from greenhousemegastore, it is just a 6x8 hobby with a manual vent. I put it up this year for transitioning hanging baskets out of my garage.

I put some Fern Leaf Bleeding Hearts in there first. They had put off shoots and were growing ok in my garage over the winter, so I put them out in the greenhouse. But, every new shoot that came up would grow about inch or two and then die. The plant did not die though just the new shoots. A nursery here said they may not like the greenhouse so I have moved them outside. So far so good on them, but they did not like the greenhouse.

I put some pansies in there and they seem ok, not growing very fast though.

But, I have also been growing some seedlings of Candy Showers Snapdragon in my garage, and just moved them to the greenhouse, and they wilted and drooped. I did not want to lose them, so I brought them back to the garage and now they are perking right up. It did not seem too hot in there or too cold, and I had it vented. They were planted from seed on Jan 3, and transplanted on 21st of Feb into baskets. They are very healthy and have about 4 sets of leaves. I am in Oregon zone 8, and temps have been in 50s, and lows in 40s outside. Temp in garage has been about 55-60's. Temp in greenhouse on the gauge said 61. These are suppose to be cool temp plants.

I am not sure why my plants are not liking the greenhouse.

I think I don't understand greenhouses. I thought the plants would like it and it would be a good transition place for them to start hardening off. Last year I just put baskets outside for awhile and brought them back in, but most did not live. I thought this would be better. Little frustrated here

Pic included of 1 basket, but it has recovered. Just thought I would include.

[applestar]

There are three elements to "transitioning" (acclimating, hardening off)
(1) temperature
(2) direct sun
(3) wind

A green house may protect from cold and wind, but doesn't protect from overexposure to direct sun. A bleeding heart is a part sun/semi shade plant in outdoor conditions, so it would be particularly sensitive to overexposure and would need careful and gradually increased amount of direct sun after growing in the garage. But even full sun plant will need to be gradually acclimated to increasing amount of sun exposure until they can tolerate the sun.

Same can be said of wind. That's why an oscillating or timer on/off fan is used to strengthen the cell walls of seedlings indoors. Placed outside, they need to be placed in protected location at first. Wind is also drying and can cause rapid dehydration. Watering schedule will need to accommodate new needs.

A green house may also get TOO hot in the sun. And unheated greenhouse can get too cold overnight. Do you have a max/min thermometer in the green house to monitor temperature ranges? Have you been checking every day? It's easier if you use a remote sensor so you can check from inside the house on the base station.

[imafan26]

Green houses are good to extend the season. The temperature inside a greenhouse can be 10-30 degrees higher and much more humid. Where you locate your greenhouse matters because if it is in a sheltered location it will stay cooler, in the sun it gets hotter and more light gets through.

If you are hardening off, a sheltered place in the yard might do better taking them out for increasing amounts of time until they are fully hardened off. The greenhouse may not seem hot but if you were to be inside it with the panels blockiing the wind and holding in humidity, it might seem a lot hotter than the actual temperature.

[rainbowgardener]

Greenhouses are tricky. As people have said, if in the sun, they can easily overheat and cook your plants.

But also they hold in a LOT of moisture and have little or no air circulation. Warm, moist, no air circulation is a perfect recipe for fungal diseases.

I am starting some seeds this year in a little mini greenhouse, shelf system. It is about like this:



but I have it in my unheated garage, with lights hung over a couple shelves. I have been amazed at how warm it stays, even when temps have been down to freezing. The only heat source in it is a heat mat under a couple of trays and the lights. Zipped up in the garage it stays 30 or even 40 degrees above the outdoor temp. And it gets full of water. In the daytime I unzip it and roll the front flap up, open it up all the way and wipe everything down. Everything is covered in water drops.

All that is not really a good thing for plants. You will need to learn how to manage your greenhouse for appropriate temps and humidity. And you need to put a little fan or two in it for air movement.

I never used a greenhouse before and now I see why!

[imafan26]

I havent used shelves with covers mainly because of the rain effect inside the tent and because cold usually is not that big of a problem except for the warm season seeds and I just have to wait a little longer.

I have lots of experience with shade houses and hot houses and it is no misnomer. It gets really hot inside a shade house and greenhouse. Shade houses have screened walls that are not solid and may or may not have a permeable roof. The small shelf type greenhouse you are talking about is like a terrarium. It will actually show condensation, especially if you water inside the greenhouse and don't let it dry out before you close the flaps. Hot houses and shade houses, are big enough and have ventillating fans so that the only condensation you see is the sweat you generate.
No one wants to be in them after 10 a.m. as it really gets too hot to be comfortable.

For your green house shelf I would leave the flaps open unless it is really cold at night. If it is getting too hot inside then move the greenhouse to a shadier spot if you can. I try not to have any plants up against a solid wall because you will block the air and get reflected heat, unless that is what you are going for. I would rather have it up against a shrub or an open fence that lets air through. Preferably on the east side so it can get some shelter from the afternoon sun.

[rainbowgardener]

If you are talking about me, imafan, I have the greenhouse for seed starting as I don't have a place to do it in the house any more, and we were having temps down around freezing for awhile. I do open it all up in the day time and wipe off a lot of excess water.

If you are talking to missiboswell, she doesn't have a shelf one, she has a 6' by 8' walk in greenhouse.

I was only mentioning mine to share my experience of how extreme the hot and wet effects can be.

[imafan26]

I missed she had a walk in one. It is still small. Usually the better green house kits come with ventilating roofs or windows or something to attach a fan to. She probably needs to open the vent more. The problem with manual vents and fans is that you have to go out and check the thermostat and turn the fan and vents off and on yourself instead of it being done automatically. The greenhouse would probably work better as a season extender since you would want it to be a little warmer then.

[ButterflyLady29]

My opinion is that your plants went from low light and low temperatures to high light and high temperatures. In other words too much too soon. The plants that you mentioned like cooler weather and since they were in the garage previously they were not used to the extra light they would get in a full sun exposure greenhouse.

[missiboswell]

Thanks so much for the great information. I was not expecting to have to take the time to acclimate to the greenhouse. I thought I could just put them in and they would be all happy. Did not really think they could not handle the sun coming in there. I have a hanging stand outside, but I was going to put them in the greenhouse and then transition to outdoors on the stand. But, I really need to be careful here in Oregon about setting them outside. We get sun, then down poor, then sun. I think they would get saturated and smooshed with the rain. They need to get a little stronger and bigger.

But, I think yall are right. I put the poor things into shock. I have started to transition them slowly and hope they will acclimate pretty quickly. I have a lot of baskets planted and wont be selling until Mid April. My seedlings have done so well this year I have too many and am running short on room.

No, I don't have a temp that I can read from the house, so I make several trips out to check. It has been pretty steady for day/night temps. I do open the vent. My pansies went in and have not had to move them. Guess snapdragons are another animal.


I do have a makeshift greenhouse stand in the garage, I just used a metal shelf with 2 shop lights on each shelf, and put plastic around it with a removable front cover. Works wonderful.

Thanks for all the info.

[rainbowgardener]

A min max thermometer that tells you what temperature it is in the greenhouse and how low it got over night and how hot it got in the daytime is an essential green house tool!

You can get them for under $20

[missiboswell]

great, I will check that out, thank you.

[Susan W]

Agreed, several factors with the greenhouse. Temps, moisture, air movement, sun and more. For the situation above, I can suggest to have the plants adjust more slowly, and use a shade cloth.

I have 3 mini greenhouses on S facing deck, against the house. There is a good eave overhang which helps, and keeps direct rain off. Even in winter if temps only 45 and sunny, would be upwards of 80 inside by late AM. I try to keep front flaps open as much as possible.

I just got a small hobby house going, sorta. 5 x 6, was a clearance item at HDep. I am watching temps, air, sun etc closely. Again, trying to keep vents and door open as much as possible for air circulation.