zacman-
Great ideas!

1. Ditto on the concrete mixing tubs. I love them as they are just the right size, they're cheap, and very tough. Also, because they are reasonably deep I am able to moisten very large quantities of seed starting soil at one time.

2. I use my seed starting mats in the winter to keep sensitive plants warm without having to keep the whole GH at a higher temp. Some of these plants I also have under tall, plastic germination domes to both conserve warmth and maintain moisture.

3. I have found a remote sensing thermostat very useful in checking on GH temps in the middle of winter. I have a 2-channel one that monitors the ambient temp in the GH, and a wired probe that monitors soil temp in the plants I have on heating mats.

[[ Oops I posted this twice: See updated post with same subject line ]]

This post was edited by Annuschka on Tue, Sep 10, 13 at 16:42

Hi,
I am puzzled by the soil needed to raise healthy tomatoes:

a) tomato seed that I carelessly threw into the capsicum plant (just potting mix) has produced fabulously strong seedlings with heaps of luscious green leaves

but ...
b) the tomato seedlings (same seed packet as above) which I had so carefully planted in "proper" seedraising mix are sickly, pale, leggy things that are not growing

As a test I took some of the sickly ones and planted them into the potting mix used for the health plants but it has not helped, they are STILL stunted ..

So what is going on do you think?
Did they just get a bad start in life ?
Or am I not managing the temperature/humidity/air-flow?

I can't "see" damping off but then I do not know what to look for: ONe or two plants looked really sick and I got worried about damping off so I quickly removed them

I gave the remaining plants a treatment of iron chelate to deal with damping off in case that was what was wrong, and a misting of miracle grow/seaweed maxicrop fertilizer.

This does not seemed to have made the plants grow.
But at least no more have died.

Background:

My greenhouse is new, double glazed (greenhouse plastic inside + polycarbonate outside)
No heat source at night
The daytime temp can get high (86F, 30*C); night times it falls to 4*C (40 Fahrenheit) and I do not use any heat source.
The daytime humidity falls and at night it gets very high.

Occasionally I switch on a fan.

I have probably over-watered them and am now being more frugal with the watering.

My discovery may be something that is just special to my region or my greenhouse situation. I live in mild zone 7b. Most of my container plants are tropical fruit trees, but varieties that can take it down to the high 20's (i.e. no mangoes) sooo I don't have to keep the air super warm. I try to keep things in the high 40's or low 50's at night as much of the winter as I can but I don't kill myself if a winter storm rips through. My greenhouse is really a hoophouse or high tunnel, metal pipe frame with greenhouse plastic sheeting covering, double layer for the roof with an inflator, roll up side walls and front and back doors (these are huge and take up most of the space). I built it on an old basketball court so there is an asphalt floor. The structure is 20 feet wide and 30 feet long. The ridge is 15 feet high which makes the need for lots of heat during really cold nights. I heat with an old but massive wood burning stove (firewood is free) with a powerful blower attached so as long as I want to sit out there and manage the fire I can keep it very warm. The problem is that about half way through the winter I start to sleep through the alarm and not get out there every 3 hours like I should. Soooo long story short - I discovered that if I make a flimsy tent out of very thin clear plastic in one section of the greenhouse and keep it about the size of a walk-in closet, I can keep that section really warm with just a simple 1500 watt electric space heater. Last year I used the super thin plastic sold as a cover cloth in the painting dept. It is so light weight anyone can cut it and hang it, it weighs nothing. I hung it from clothesline strung across the span of the greenhouse and kept it in place with clothespins. easy easy easy. And it saved all my tender seedlings and orchids the few nights we got really cold.

My only other tip would be those clothespins and small clamps. Working around plastic sheeting and rope and such, everyday I find a different use for them. Cheap and oh-so handy.

I use those mortar-mixing tubs too :)

Kiddie pools are the cheapest large plastic bins for watering plants, especially those in gallon pots. When summer comes and the greenhouse gets over 100 degrees, the only plants that live are the ones in a few inches of water in the kiddie pool.

re: sickly tomatoes.

What nutrients were you fertigation your seedlings with? I'm guessing that your specialized seeding media is a sterile soilless media that doesn't have any nutrients in it and you either didn't add any or didn't use a proper hydroponic fertilizer so the plants did not get enough nutrients whereas the potting soil has nutrients in it already. Just a guess.

To see if there is damping off, take a look at the stem at about the point where the media level is. if there is an area of the stem that is thinner than the part above it, you likely have damping off.

I am retiring in 5 mo. and my wife and I are wanting to do a lot of veg. gardening. We live on 2.2 ac. and we will be clearing behind the house. I'm presently looking at a 20'X44' greenhouse (commercial duty) from a pro. greenhouse ( local) manufacturer. My wife's brother lives upstate NY and we live in SE Texas. He(wife's brother) has a nursery with 5--35'X90' greenhouses. He knows a lot about greenhouses except planting zones are far apart and any advice on plants is pretty useless. Need someone close to me to help with advise on greenhouse veggies and berries. I do know greenhouses are a lot of work and can be a lot of fun too. What is a good book or dvd on year round growing vegs. in a greenhouse? We are real newbies. Also have a neighbor, 2 doors down, who is going to retire next June and is also interested in a garden and greenhouse. Any help from an old-head?

Steve - I would first look into all the new info on High Tunnels and Hoop Houses. They don't give you the 'conservatory' look of a glass house but they are so much cheaper and easy to build. The folks that sell them and often install them have all sorts of gizmos and tools that make growing a crop in them easy. Get a catalog and just read the text about the various tools and systems. I find there is more current info there than in any book.

I am new at this so thanks for your helpful tips. I am making a copy of them to keep them handy. Also, I posted, "1st greenhouse" will you take a look? I am interested in any advice you can give. Thanks