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Thread: Greenhouse Update

  1. #561
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    Default Re: Greenhouse Update

    That is one heck of a set-up.
    "Please be more specific or we'll choose to order a cheaper bilge-rat to replace you."

    ~seanz

  2. #562
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    Default Re: Greenhouse Update

    Thanks! Here's a bit more on the temperature control setup.

    As you can see by comparing the indoor and outdoor temps, there are some broad temperature gradients involved.



    34.9░F is a mild outdoor reading for midwinter. On a clear, cold day, it might be 5░F outdoors and 90+ inside. There are thermally driven ceiling vents that I set to open just a crack, while usually block the intake vents.



    When the outside air is cold, a direct draft can damage or kill tomato plants. (The plant shown is a goji berry I started from a cutting.)

    Besides the Taylor digital thermometer, I have others to help me balance the heat—



    A soil probe thermometer shows the temperature of the main thermal mass, a rammed sand floor, 12' x 12' x 3' deep. I laid down a mat of reflectix slab insulation and 2" foamboard before filling it. The soil temp outdoors is around 10░F, so the combination of direct solar input and heat from the flat-plate collector maintains the floor temp within a decent range for plant growth.

    The wired probes for the Taylor digital thingie quit working after a year or two underwater, so I went to a pet shop and got a cheap aquarium thermometer. The reflection obscures the 9: the water i the 400 gallon heatsink under the floor is 98.3░F. I usually start pumping warm water through the floor when there's 20░F difference in the temperatures.



    The one thing missing is a photo of the combination temperature/pressure gauge on the glycol loop that conveys heat from the flat plate collector through coils of PEX tubing to the water in the big heatsink. The pressure ranges from 10 psi up to 20 on sunny days, and the incoming fluid reads 100░F up to 140░F or so.

    All this is fairly automatic, so I don't have to dash out to the greenhouse every time the sun goes behind a cloud. The main thing that needs watching is when the flat-plate collector is clear, heating the lycol solution, while the 20W PV panel which drives the pump is covered with thick frost or snow. It's blown up twice under those conditions (popping the end of the PEX tubing out of a joint). The fix is to cover the collector, refit the tubing at the joint, recharge the loop (glycol and water) using a drill pump, and then start it up again.

    Worth the trouble, I reckon. Here's yesterday's pick—

    We're merely mammals. Let's misbehave! ŚCole Porter

  3. #563
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    Default Re: Greenhouse Update

    The strawberries have been looking sad, with reddish edges on the leaves, which eventually wither. I suspected a soil fungus, owing to wetness, so I lifted the plants, then scrubbed the pots and doused them with boiling water. They have built-in drip cups underneath, that hold water and keep the base of the pots damp. So I popped those off and put a gravel/sand mix in the bottom of each pot, for drainage. Then they they were refilled with new soil.



    The bed of greens is getting jungly. Maybe a good night for kale.
    We're merely mammals. Let's misbehave! ŚCole Porter

  4. #564
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    Default Re: Greenhouse Update

    Quote Originally Posted by Portland View Post
    We have only experienced our greenhouse over a hot summer, so far.
    If you scroll back to the early pages, there are photos of the passive vent system, which depends on thermally-powered pistons to open and close vents. Since our summer air temps seldom exceed 28░C, the low-to-high venting keeps the inside air below the point of damage for most plants, although spinach tends to bolt quickly.

    A further passive measure is to use reflective net panels stretched over the roof and sun-facing walls. Greenhouse growers in warm climates often have big tip-out side panels (which allow bugs in, alas) or blowers on thermostats, or even evaporative coolers.
    We're merely mammals. Let's misbehave! ŚCole Porter

  5. #565
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    Default Re: Greenhouse Update

    Quote Originally Posted by Chip-skiff View Post
    Thanks! Here's a bit more on the temperature control setup.

    The one thing missing is a photo of the combination temperature/pressure gauge on the glycol loop that conveys heat from the flat plate collector through coils of PEX tubing to the water in the big heatsink. The pressure ranges from 10 psi up to 20 on sunny days, and the incoming fluid reads 100░F up to 140░F or so.

    All this is fairly automatic, so I don't have to dash out to the greenhouse every time the sun goes behind a cloud. The main thing that needs watching is when the flat-plate collector is clear, heating the lycol solution, while the 20W PV panel which drives the pump is covered with thick frost or snow. It's blown up twice under those conditions (popping the end of the PEX tubing out of a joint). The fix is to cover the collector, refit the tubing at the joint, recharge the loop (glycol and water) using a drill pump, and then start it up again.

    Worth the trouble,
    Once again, excellent thread. Thank you.

    The other thing that's missing is a relief valve, or better yet, an expansion tank designed for hot water systems. For $35, a 4.5 gal tank can absorb 2 gallons of expansion before it hits 20 psi. There is an even less expensive 2 gal one at HD, but it's hard to tell if it has a valve stem to adjust the starting pressure, and they don't say what the preset is. The 4.5 gal tank is precharged to 12.5 psi and the lump on the bottom of the pic looks like a valve stem. The rubber parts are butyl, so glycol should not have any effect on them.

    This is an easily searched example with a picture. I don't know enough to recommend any specific brand:
    https://www.homedepot.com/p/Series-E...T-30/100579128
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  6. #566
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    Default Re: Greenhouse Update

    Quote Originally Posted by MN Dave View Post
    The other thing that's missing is a relief valve, or better yet, an expansion tank designed for hot water systems.
    Sharp eye. The pressure/expansion tank is hidden under the floor, by the end of the 400 gal. heatsink. I try to run the glycol loop between 10-20 psi.

    There are also two relief valves on the flat plate collector, at the upper right and lower right corners:



    The lower one is a standard fluid pop valve, like you'd use on a water heater. The upper one helps to exhaust air bubbles or something. The glycol loop has blown up only once, when the flat palte collector was clear of snow while the small PV panel was covered, so the fluid was being heated but not pumped. I go out and check most mornings to prevent a repeat ka-blooey.
    We're merely mammals. Let's misbehave! ŚCole Porter

  7. #567
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    Default Re: Greenhouse Update

    What to do for Earth Day? Celebrate with fresh-picked tomatoes and greens!



    This is an unidentified volunteer plant that sprouted in a bed of spinach. I don't recall growing anything of the sort: indeterminate, dark red, variegated, tendency for cat-facing and cracks. Rich, winy taste.

    Here's another mystery guest:



    Indeterminate, yellow-orange, clusters, ovate and slightly pointed. The yellow tomatoes I grew that volunteered like mad, Galina, are determinate, smaller, yellower, and lack the point. Haven't tasted this yet, as it's only just ripening. I have to decide whether to name these and save seeds to see if it breeds true.

    On the tail of winter, the tomatoes were bushy and rank, so I started some new plants and then did a savage pruning to let in some light.



    The garlic rows in the center bed will soon be set outdoors, to see if I can get usable garlic. I used to grow top-setting garlic, which these ain't: just some from the market that were sprouting in the cupboard. The San Marzano type tomatoes at right are a couple years old, and the fruit has gotten rather small. I'll cull one plant and prune the other two, to see if they'll buck up. There's one Sun Gold tomato that's been cut back to the stump about five times, and it still produces good fruit.



    The original stem is about 2"/5cm thick. Here's a shot from before it was pruned. The fruit is round, medium orange, low acid, and very sweet. Kids love it.



    Here are two more, with a black cherry tomato on the left that's been amazing both for vigour and fruit. Note the old, thick stem.



    The other is an unknown volunteer baby, that's grown really fast and is just flowering.

    (More on page two.)
    We're merely mammals. Let's misbehave! ŚCole Porter

  8. #568
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    Default Re: Greenhouse Update

    This is a black plum tomato, setting smaller fruit. I'm guessing that the first unknown variety is a crossbreed of this and the Moskvich, a red heirloom with a point.



    The plants were intermingled.

    In the center bed, besides the garlic there's mixed lettuce. I just planted greens, including the Hakurei Japanese turnip that Sibbo recommended (L), that came up a day-and-a-half later.



    Here 'tis on day 3—



    Easter egg radishes (tri-coloured, L) and two rows of Hakurei turnip.

    Must be harvest time for the Aussies and Kiwis.
    We're merely mammals. Let's misbehave! ŚCole Porter

  9. #569
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    Default Re: Greenhouse Update

    Do you ever graft tomatoes ?
    I'm thinking of trying as I have a soil borne disease that kills tomato plants just as they begin to set fruit. I've recently successfully grafted eggplants onto a disease resistant weed species root stock, the results should be good.
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

  10. #570
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    Default Re: Greenhouse Update

    Quote Originally Posted by PeterSibley View Post
    Do you ever graft tomatoes ?
    I'm thinking of trying as I have a soil borne disease that kills tomato plants just as they begin to set fruit. I've recently successfully grafted eggplants onto a disease resistant weed species root stock, the results should be good.
    I've grown plants from cuttings, but never tried grafting. So far, the tomatoes are free of disease and pests, unlike peppers, beans, cukes, and other plants that are prey to aphids and a mosaic virus. I thought about grafting several varieties onto one rootstock, for a plant that bears 3 or 4 different sorts of tomatoes. But that would be a stunt, and the tomato gods might take offence.
    We're merely mammals. Let's misbehave! ŚCole Porter

  11. #571
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    Default Re: Greenhouse Update

    This the way I've done it , both are solinacae.

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    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

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