What do mean they look "parched?" If the soil is still wet or damp... how can they look parched? Do you mean they're turning brown and drying up (crispy?)?

Twenty two percent sounds really, really low. Is your heater on? Are you ventilating?

I will stick my neck out here and guess that part of the problem is your potting medium. What are you using for a growing mix?

SB

For a logical reason for your problem, we need more information.
1. Did all plants die?
2. What is the make up of your soil, did you add anything like fertilizer?
3. What was the Day time and Night time temps.
4. What kind of heater do you use if any?
5. How much sun do they get?
6. What type of plants were they?
7. How long were they in the GH before they started looking sickly?
Most plants have a relatively wide tolerance of humidity and water as long as you donÂt drown them. Altho in winter they require much less water.

John

by parched, I mean wilted and limp, loss of green color not crispy. I developed some black sooty mold on the corn plants. The soil was too wet but the air so dry. I grow mostly just common houseplants. I had a real big problem w/ spider mites, common for dry air.

I use packaged potting mix from Walmart. Sterns? maybe thats the name. however, many had very old potting soil from the cheap bags that say potting soil for 1.49 that is kept outside at stores. And it could have been compacted. I have started to make my own this summer w/ perlite, peat, and vermiculite. I tend to under fertilize.

night temps usually no colder than 57-60 and daytime could reach as high as 95-97 heater rarely came on. gh faces south and west w/ north wall being our walk out basement and east wall mostly block w/ 2' being poly.

Half way through the winter they started looking bad. about Jan. Hope this helps with possible solutions.

House plants will do fairley well at 20% humidity. I would bet my GH and everything in it, that you drowned the plants. It sounds like they are too wet for the summer mos, when the plants are activly growing.I would wait untill the soil is dry before watering. If you check your plants often you could wait untill you see EARLY signs of wilting. What type of misters do you use? The mist should evaporate in the air and not reach the pots/soil. John

It sounds like a root problem to me. To wet, for to long, spells root rot. Both root rot and to dry at the roots will cause wilt. Simply put, one way or the other, the plant isn't getting enough water. Rotting roots are doing nothing for the plant. I think you are putting to much into humidity right now. Let that go for a while, and dry out these plants......... Tropicals LOVE water, and where they grow in nature they are soaked daily but that water drains very quickly away, and is taken up into the canopy of trees in the form of fog. They are left moist, but not soaked. The heat and light wind dry them off. Water at the roots is never stagnant (like in a pot), it keeps moving. Dry them out for a few days and look them over again. A well draining mix might be better for these plants..............Good Luck..........
Pat..........

I'll agree with the consensus with root problems. Repotting into a quality mix with added perlite should help the drainage problem. Skip the vermiculite, it holds too much moisture. Pro Mix is a great medium for $25 a bale around here and I cut it with perlite, mixed 50/50.

Have you checked the humidity of the gh at night? It is common for the humidity to drop during a bright sunny day and get extremely high at night. Your misting system should be installed under the bench to keep the foliage dry. Wet, cool temps, lack of air movement on the plants can lead to fungal and bacterial problems.

Brooke

John,

I think I need help figuring out the best way to use the misting system. The mist is not evaporating totally, like you say it should. It does at first, then it keeps going to reach the level I've set it at (40%) but like I said earlier, my digital readout (separate from the misting system) says its going higher than 40%, more like 55-57% and then it shuts itself off. Which would be ok, I guess but then its so warm in there right now, that the exhaust fans come on and dry the air out again, causing the misters to come back on. I'm using 2 different outputs of misters. One is 1.7 gal (white tips) I think and the other is 2.4 gal. (blue tips) bought from Charley's Greenhouse Supply. Maybe I should switch to all 1.7 gallon tips?

I have the misting system set up on a humidistadt, not a timer. should I be using a timer instead? I thought that might put too much in or not enough. I thought the humidistadt would do a better job at regulating it. I have the circulation fans plugged into a photocell so they wont come on at night. Right now they run for 3 minutes every 15 minutes. And the exhaust fans are temperature controlled to come on at 85-90 degrees.

My plants don't stay in the gh during the summer months. I take them out usually in late April or May. I've just put them back in a few weeks ago. But here in southern Indiana the temp is fairly warm still. like 60-70 degrees in day but can dip down at night. we had 37 degrees early this morning. We usually have high humidity in summer, this drought has done a number on lots of landscapes.

Pat,

I think you're right. I drowned them last winter. I will be using my water meter to make sure they really need it and not go by their looks this time around.

There are several factors contributing to your problem, and humidity is the least of them.

First, roots need oxygen to function. The soil you are using has relatively low macroporosity and is easily compacted. In a low oxygen environment, plant roots cannot take up water and nutrients adequately to meet the demands of the top of the plant.

Second, you have wide temperature swings in the GH. At the lower end of your temperature spectrum, in the upper 50s, your plant roots are not working at their best. Now, consider the water needs of a plant suddenly warmed up by bright sunlight and a warm GH. It's photosynthetic engine wants to get cranked up as the foliage temps rises, but with the soil temp still low, the roots are unable to take up enough water or nutrients to meet that demand.

These two factors cause wilt, contribute to stress, weaken the plants, and make them more susceptible to pests like spider mites.

The continually wet, poorly oxygenated root environment leads to root rot.

Your solution starts with a different potting media, IMHO. Go to the Container Plant forum and look for the 4 threads (or 4 parts of the same thread) by Tapla that start with "Water Movement in Containers..." or something like that. There you will find a good explanation of why peat-based soils are a poor choice for long-term container plantings. Replacing your container soils with a large-particle mix using perlite, bark, CHC, Turface, or grit and you will go a long way toward correcting your problem.

Forget about your water meter, most are very inaccurate. Learn to water by judging the weight of the container.

Other steps might include diffusing the light and moderating the temps.

Good luck.

SB

A couple of other thoughts...

Humidity is the hardest of the three GH factors to control...light and temp are easier...and it is the least important. Why do you even need mist right now? My misting system has been off for weeks. If you must use mist, put it on a thermostat rather than a humidistat and work toward temp control instead.

Promix is a peat-based mix (up to 70%) and IMHO is fine for short-term plantings of 3-6 months, but used straight is subject to compaction used longer than that. I sometimes use it as a component of my mixes but it is only 20% of the mix. See Tapla's treatise.

SB

Hello Pat, this is my opinion but it is based on many years of experience with measurement and control systems. Humidity gages and humidistat are next to worthless. The amount of moisture in the air is extremely difficult to measure. The only way to come close is to swing a Wet bulb thermometer in the air and measure the temperature drop due to evaporation. I have a misting system that I only use in the late spring and summer in an open GH to root cuttings. When the GH is closed, I use a Sunbeam steam humidifier that puts one gallon of water in the air over a 10-12 hr period. I only run the humidifier for 1 hr per day and when the outside temperature drops to 50 Degs, the ceiling and walls drip so much water you would think its raining inside. My GH is 8.5ft X 8.5ft let me know if this helps. John

jaime

Everyone has given you excellent advice so there is little I can add. I would run those fans 24/7 or close to it. Stale, stagnant, damp cool air isn't good for plants. Also, try opening the vents or door on sunny days to let fresh air in and keep the temp down in the 70s or 80s.

The cheap Wal*Mart soil is useless. Please purchase something a little better. I make my own by mixing topsoil from Lowe's with peat moss, perlite, coarse builder's sand, some compost from our compost heap, Lowe's soil amendment which looks like small broken tree bark and add a handful of Ironite, blood meal, bone meal and wood ash.

thank you everyone for all the great advice. I have lots to learn.

I'm pretty dissappointed at everyones view of the misting idea. I was just sure that would solve my problem. :(
I also wouldn't have spent all the money on it.

John, boy, I sure wish I knew about your Sunbeam humidifier before going to all this trouble. While my gh is larger than yours (16'x 25') surely a little more time with it on may have done the trick. talk about an expensive lesson. I didn't think anything that small would have made any difference.

SB, I am going now to look up that thread - thank you for that and your terrific knowledge. btw, my gh will only be that hot for a little while and then just for a short period of time as old man winter is creeping this way.

Greenhouser, thank you for your mix recipe, I didn't think it was a good idea to use outside compost on inside plants? but that it totally do-able. Also, it costs me $150/mo to run those fans 12 hrs a day - not exactly in our budget, so I got a timer that can run them many times for as long or as short as I want. But my exhaust fans (vents) come on for me automatically so I've got that covered at least.

Thanks again to you all, I am so pleased with everyone being so helpful. The Gardenweb's community is great.