MOFishin
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Where do I start with greenhouse gardening?

I'm already looking ahead to next year. This year, we had a couple late frosts here, followed by lots of rain, and overall we've been having a pretty chilly spring.
Next year I want to start some seeds and get things going early, regardless of the weather conditions. I don't know anything about growing indoors or in a greenhouse. I've been browsing online and seen a lot of surprisingly affordable greenhouses. I was thinking about getting a little mini-sized one. But where do I start? What are the basics? If I'm wanting to start seeds indoors and transplant into my garden outside later, should I just keep them in my house? And if so, should I buy a grow light? I know these are very broad, general questions. But I have no idea what I'm doing (Or plan to be doing in the future, I should say).
Thanks.

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rainbowgardener
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Definitely if you are going to start seeds indoors you must have grow lights and heat source. If you are going to start seeds in a greenhouse you probably need growlights and you definitely need heat. Personally I've not used greenhouses (much) and think they are expensive to buy and maintain in return for the small amount of time they are really useful.

I have one of those mini - green houses that is basically a shelf system with a plastic cover. I got it to be my new seed starting set up after I moved. I put it in the unheated garage. Hung lights over two of the shelves and put heat mats under the trays of seedlings. It worked out pretty well - in our pretty mild zone 7b winter, the heat mat and lights were all the heat source I needed with the cover zipped. Next year I will put vent holes in the top; it kept in way too much water.

In this thread (scroll down to the bottom of the page) https://www.helpfulgardener.com/forum/vi ... 79&t=67820 someone showed a picture of his seed starting set up, a DIY shelf set without cover, but with heat mats and lights, in his heated shed.

Other people of course, swear by greenhouses, so maybe one of them will come by to give you the other viewpoint.

See also seed starting basics, here: https://www.helpfulgardener.com/forum/vi ... 48&t=44183

j3707
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Hey MO! I want to get a greenhouse going, maybe a small one next year if I am lucky.

This year was my first starting plants indoors. I had one bench set up in my garage with grow lights. I let the seeds germinate in the house where it was 68-70 degrees. Then I put them out under the lights.

I suspect that having them in an unheated area makes it easier to harden the plants off before planting outside as they are already used to lower temps. Maybe others can comment on that.

I suggest starting plants indoors or in a garage next year and see how that goes for you. After that you would have a better idea if you need a greenhouse or not.

For lighting, I used two t-5 high output fixtures with 4 bulbs each. That was enough light for 4 or 5 seedling trays. Some people use t-8 or t-12 fixtures, they are less expensive, but they put out less light.

MOFishin
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Location: Central Missouri 6A

Thank you both for the replies. I'm thinking starting seeds in the garage with a light/lights is probably all I'm going to do next near, although the idea of a mini greenhouse is still on the table.
What kind of lights do I need and how much does a good one cost? I will be doing this on a budget. I don't know how much exactly as this will be months down the road. But I can't spend a lot. I've browsed growlights for sale online, but I don't know much about them. I will probably be starting a bare minimum of 60 seeds, but at varying times.

j3707
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MO, you'll want each seedling to grow straight up toward a bulb, so you'll have to figure how much total area your seedlings will take. Then you can figure out what size light fixture, or how many of them, you'll want.

4 foot fluorescent shop lights are commonly used for starting plants indoors. If you don't know, there are a few common types of fluorescent bulbs. T-5 is the highest light output and the most expensive, T-8 is cheaper and probably just fine. The shop light you buy has to be one or the other, a T-5 fixture won't take a T-8 bulb and vice versa.

Just to give you a ballpark, the 4 foot t-5 fixture I bought was about $90 (not including the 4 bulbs). That's the t-5 "h.o." (high output), which is nearly top of the line as far as shop lights go. With the right bulbs I could probably grow tomatoes indoors...

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rainbowgardener
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This was the seed starting operation I had for years (until my recent move):

Image

Notice how close the lights are.

You just need fluorescent tubes in shop light fixtures, but they need to be very close to the plants, hung so they can be raised as the plants grow.

That was in the heated basement at my old house. I did have a couple of heat mats for germinating the seeds. After the seedlings had true leaves (maybe a couple pair), they were moved off the heat mats and new seeds planted there.

MOFishin
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That looks nice rainbow gardener. I was just sitting here wondering about that heating mat situation. So, I can just use a heating pad like people use on their aches and pains, and put it under the seeds I'm trying to germinate?

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rainbowgardener
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Well you can, and that's what I had in the picture of my old set up. But those were years old (amazing over-engineering, I ran those things 24/7 3 months a year for 15 years and they never died!). The modern ones usually have automatic timed cut off, which won't work. For about the same price as the heating pad for people, you can get plant ones:

Image $22

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Gary350
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My idea of a green house is to start small seeds than need to be germinated where there is still frost and freezing weather outside. Also I would like to have tomato plants in a green house in the fall so I can have fresh garden tomatoes until January.

Till your garden in the fall and mark the rows with stakes and string. Some seeds can be planted in snow when the weather gets right they will germinate and grow right in the garden rows.

Some cold weather plants will grow for many years as long as it does not get cold enough to kill them. I had Kale that lived 4 years once it gets bitter in hot weather but is good to eat in cold weather. It lived through 3 weeks of -17 degree F weather. I dig it up to move it to a different location and it died.

I use to plant tomato seeds in plant trays and get them started in a Hot Bed this is just a window over a short 8" tall wooden box setting in the garden. Now days I save tomato seeds plant 10 seeds every place I want a tomato plant in the garden when weather gets right they come up and the strongest plant takes over.

There is no reason to start large easy to grow seeds in a green house unless you have a very short growing season or just want to get an earlier start in spring.

Here in TN 2nd week of July tomatoes always appear to have blight and die but I have learned the extreme heat is the real problem when temperatures hit 100 degrees every day plants died if I can plant my tomatoes in the ground April 1st I get a 1 month head start on the tomato season but I have to start seeds last week of February then plant them in the garden April 1st and cover them with 5 gallon buckets every night until frost and cold weather is over. I harvest my first tomatoes first of July and I want to harvest 300 lbs of tomatoes in 2 weeks before heat kills my plants.

Years ago I experimented with green houses, 2 layers of glass is a good insulation and holds in the heat very well in 20 degree weather in full direct sun it got 100 degrees inside but an identical green house with 1 layer of glass got to 70 degrees inside. Every time temperature outside goes up 10 degrees temperature inside the green house goes up 10 degrees. You need an temperature controlled air vent system with fans to bring in outside and and blow out the heat to keep from cooking the plants. In 40 degree weather 1 layer of glass gets 90 degrees and 2 layers of glass get 120 degrees.

RadRob
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Sorry for the long post but I was bored and you asked, I hope it helps and I hope more people consider getting a green house. Even if it's just to extend your fall tamato growing with a few plants, I'll be having fresh homegrown tomatoes for Christmas and after the 1st it's time to start peppers and eggplants for next year. Enjoy!!

Getting a GH is great and will extend your season in Spring and Fall. I would say IF you're a gardener and garden all year every year then you need to get one bigger than you think. I started with a 7'x7'x15' and it seemed like it would be plenty big enough but it filled up quick with a dutch bucket hydro system with 8 plants and then when seed starting came it got full with plants every where and I also used it to over winter plants.

Here's the 1st GH
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You can see I used 2"x4"'s cut in half and cemented in the ground for supports and used EMT straps to secure the GH to the wood and built a plant shelf.
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I just checked the price for a friend and they're cheaper than it was 3 years ago, $91 with free shipping. The plastic will last about 1.5 years so plan on replacing it with good stuff in the future.
https://www.ebay.com/itm/Large-15x7x7-Wa ... SwoydWlgH6

OK, this is how full it gets
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As you can see, it fills up in no time. I just built a bigger one for this year and now I have 2 to fill up again.
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This was 3 weeks ago
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and now
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over wintered peppers under the shelves
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a few other tender plants I want to keep going through winter
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As you can see, IF you garden all year get a bigger GH now instead of having to buy another one in the future.

On the seed starting: You don't need an elaborate system or area to start thousands of seeds. You'll need space to put them when you transplant and that's where the GH comes in handy using a small heater to keep temps at about 50-60 at night. The key is to time your seed starting so you don't have too many nights with cold temps so you won't have to run a heater, sometimes we can't predict the weather so it's a guessing game. You can also just start your seeds about 9 weeks before your last frost date and that will give you a 3 week head start but remember the plants will be bigger so you might need to transplant them again. You also need to be aware that even older plants that are too close together will get leggy too so make sure you give enough space between plants so all of the leaves recieve sunlight.

I use a small area to start seeds with only 2 24" grow lights from Wally World and once they have the 1st true leaves I put them in the GH and transplant into either a 4" pot or 16oz Styrofoam cups. What ever container you use make sure it has drainage holes and don't water until the soil is dry and always bottom water.

I start seeds in a community container to reduce the space I need for seed starting.
There's 16 different types of tomatoes in that tray and more than I needed but I gave many away after I chose the best plants after transplanting.
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I used the back patio before the GH and Gumbo should recognize that custom made crawfish table.
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I use a seed heat mat to start the seeds and this is the cheapest I found that works. I ordered 4 and shipping was $11 so the price for each one came to to about $12. https://www.zenhydro.com/ipower-seedling ... wAodbNQP6g

I didn't invent the system I use but instead take parts from experienced growers and adapt it to my growing methods/conditions and have had success.

This was taken out of the book "Greenhouse Tomatoes, Lettuce & Cucumbers" by S.H. Wittwer & S. Honma where they recommend 'Cold Treatment' for hardening off tomato seedlings and grow healthy, stocky plants.
The cold treatment should be started just as the first true leaves emerge, whether the seedlings are still in seed rows or pricked-off. Air and soil temperatures should be lowered to 52 to 56 deg F for ten days to three weeks. A ten to twelve day cold treatment is adequate during periods of good sunlight. Three weeks are usually necessary in the fall and early winter when most of the days are cloudy and plant growth is slow. The amount of cold during the ten-day to three week period is more important than the time of day in which it is given. Cold exposure during either the day or night, or both, is effective. Night temperatures of 52 to 56 deg F are recommended when the days are sunny and partly cloudy.
Following the cold treatment, night temperatures should be raised to 58 to 62 deg F. Cool daytime temperatures (60 to 62 deg F) should be maintained in cloudy dull weather. On bright sunny or partly cloudy days, temperatures of 65 to 75 deg F accompanied by good ventilation are suggested.
Tomato plants properly exposed to a cold treatment develop large cotyledons and thick stems, with fewer leaves formed before the first flower cluster, up to double the number of flowers in the first, and often the second clusters, and higher early and total yields.

Basically this cold treatment is used to give healthier, more stocky seedlings that will give increased yields and earlier harvests. In regards to light intensity and duration they had this to say.
The tomato is a facultative short day plant which flowers and fruits earliest if the day is not extended beyond 12 hours by artificial light. Young tomato plants do not need the light intensities of full sunlight. Where there is no overlapping of leaves, light saturation is reached at intensities from 2000 to 3000 foot candles, or about one-fifth to one-third the intensity of direct sunlight at high noon. If artificial lights are used, an intensity of at least 500 foot candles should be provided at the leaf surface. Tests with fluorescent fixtures reveal that Wide Spectrum Gro Lux is slightly superior to cool white.
Hope this helps.

And CRAIG LEHOULLIER has great videos showing you all aspects of growing tomatoes from seed starting to pruning. https://www.craiglehoullier.com/resources/

MHPgardener's video about transplanting https://www.youtube.com/watch?v=u_YYEUcr45M

imafan26
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Greenhouse are great for season extenders but if you want to use a greenhouse for growing to maturity there are a lot of other things to consider.

A greenhouse is a controlled environment so it is not natural

Air, light, water, food and pest control need to be provided for by you.

The size of the greenhouse depends on how many plants you are going to put in it. Most people underestimate how much they can get inside.

You need air so plants need to be spaced so air can circulate and you need fans to move the air. Preferably a fan on each end one to pull and one to push air makes it more efficient. To prevent overheating and to get rid of hot air in summer, you need vents either side windows and a roof vent. A temperature and humidity guage is helpful here.

You can plant directly in the ground or you can put the plant on benches. It is better not to store growing media in the greenhouse.

You need to get water in the greenhouse to water the plants. Either water by hand or have an irrigation set up.

If you have a clear membrane you should not need lights unless you work in the dark or you have really short days.

Sanitation and pest control will be a major undertaking. Pests in a greenhouse are difficult to control once they get in because there are no predators. Fungal and algae can build up so plan on having to sanitize the green house regularly. Sick plants need to be sacrificed. and pests have to be excluded or taken care of before they get out of control, otherwise you will have to sanitize and start over.

If you are using a breathable fabric or poly sheathing, you still have to plug the holes eventually.

If you are using the greenhouse as a season extender, you might want to get a more portable model that can be stored or moved when not in use. You may have to heat the greenhouse in winter for use then.

If you are just starting out. The garage or a shed can be turned into a temporary greenhouse to start things early. Then you only would need some shop lights, a heat source, water, a bench or rack, and starter trays.

The farm built 8 new hydro houses but they were based on a Swedish design and my boss closed the roof vent because the birds were getting in. However, that cut off air circulation since the house has breathable cloth sides but a water tank up against one of the walls blocking air. A section of the green house is in the dead zone where there is no air and no fans in the greenhouse, so the plants there always look bad. Fertilizer cannot fix problems caused by poor air circulation or pots that are undersized.



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