sprouted up nicely but just not making much progress. I've fertilized too. We've had some overcast days but also sunny ones. It's in my GH and I think getting plenty of light. Temp in there runs between 53 and 65. Not sure what to do to encourage it along. Gourmet lettuce blend seems to have same problem problem. Needs to grow!

Your two weeks (more or less) away from the solar minimum. Growth should resume on warm days after the 21st.

Carol, the shortness of the day probably is slowing them down. They need longer days as well as warmth.

Maybe putting a light in there would help - add several hours of light before dawn or after dusk.

Thank you all for the great ideas. I'll try them. Appreciate it.

Dear Carol, I hope your spinach grows! When cooking spinach if you put some ground nutmeg in with it, it takes the acid out of it!
Tastes much better.
Regards.
Neil.

NEIL thank you for the tip! I will try it.

Th ank you, Neil -- I will be trying that as well, I love spinach but the oxalic acid factor definitely kind of grates on my teeth!

I'm also beginning to think maybe I should have planted it in October instead of November? When I think about lights...all I have in my little 6 x8 is a clip on regular incandescent bulb. Should I try to rig up some sort of long hanging fluorescent grow light? I've read about keeping them just a couple inches from the plants, but my plants are all along the walls so thinking about how I should do this.

I also saw on the web where someone attached four rows of gutters all along one inside wall and she grows her spinach and lettuce in those. Very space saving and she can still put plants on the floor in front.

Dear Sandy and Carol, my Doctor taught me that tip! Not too much ground nutmeg though! It does work with getting rid of the acid, and spinach is very good for you!
Regards.
Neil.

@rickcorey do you think a shop light with 4 bulbs 6500kelvin hung from ceiling in my6 x 8 GH would provide enough light for the spinach and other plants, or do I really need several lights that I can hang on the shelves just above each long planter (more costly and setup). I just have things me herbs, spinach, arugula, radishes. That kind of stuff. But it's all growing really slow. Would one ceiling light with the four bulbs solve my need?

Ecscuba said: It's in my GH and I think getting plenty of light. Temp in there runs between 53 and 65. !

Is that the temperature during the day, or is it the difference between day and night? If only during the day, what is the night temperature?

With the lights, it would depend on what you are trying to do. If you think the problem is light intensity (brightness, or the amount of light) then you'd need more lights such as fluorescents. If you're trying to alter the photoperiod (length of day) by increasing the hours of light then an incandescent is fine and that doesn't take a lot of light (the wavelength is what's important). But, having said that, you need to be very careful about lengthening the hours of light per day for spinach or it will bolt. How many hours of light are they getting currently, natural plus artificial?

Also what is your fertilizer analysis?

@sooby the spinach is growing so slowly and someone suggested I need to lengthen the light. They are in a greenhouse and get light from about 730 am until 5 when the sun sets. Everything else is slow too so I'm trying to muddle my way thru my first greenhouse experience and figure out what I need to do for them.

Spinach likes to be cool and it flowers (bolts) when the days get longer which is something you don't want to happen. It's difficult to find a consensus on how long the days need to be before they bolt and it depends on the cultivar also, some are slower to bolt than others. I would not to exceed 11-12 hours of light. Some plants flower based on the length of day, those that flower when the days are long are called long-day plants. Spinach is a long-day plant hence you need to keep the hours of light below the number that will cause it to flower.

A temperature around 60 degrees F should be OK for spinach, so I was wondering if there isn't enough of a drop in temperature at night. Alternatively, a plant's growth will be limited by whatever nutrient is in short supply which is why I asked about fertilizer analysis.

@sooby thanks. I am using an organic fertilizer. Will have to check the ingredients in that when I go out to the GH later. Thanks so much for all the info on the lighting. I'm new at this and probably impatient too. Grow, grow, grow.

I agree that "brightness" and "daylength" are different issues.

If things are growing slowly because the light is too dim, and you need more intensity to improve growth, then one lighting fixture might need to be fairly close to the plants and only "brighten" a patch a foot or so wider than the fixture - say half of your 6x8 GH.

But if they are growing slowly because they only have 9.5 hours of light per day (7:30 am to 5 pm), then adding 2 to 4 hours of weak light might be enough to convince them it's Spring, not mid-winter.

I don't know how much light intensity it takes to affect daylength, but I heard of one crop where the full moon was almost bright enough to mess up its photoperiod. If that's a guide, then four T5 tubes are bright enough to "wake up" a 6' x 8' area.

How long a day is too long to avoid flowering ?

"Spinach (some types) critical day length: 13 hrs."
http://assoc.garden.org/course...

"Most present-day spinach varieties will initiate flowering when the daylight duration reaches 14 hours — as early as mid-May in the northern half of the United States."

Read more: http://www.motherearthnews.com...

Maybe you should aim for a "day-length" between 11 and 13 or 14 hours.

P.S. Or you could think of your greenhouse as only "overwintering" a crop of spring spinach - providing plants with established root systems that are poised to grow rapidly as soon as outdoor daytime lengthen and soil and air warm up.

I've read a few people say that their "winter crops" of greens are more like holding plants in a refrigerator. The plants don't grow much, but they stay alive until they are picked.

You might look into different varieties of spinach for a winter greenhouse crop.
I see there are distinct 'spring" and "fall" varieties of spinach:
http://www.johnnyseeds.com/ass...


Johnnys Seeds says:
"In the North, spinach can be grown in a hoophouse right through December. The key is to have the spinach established before the day length drops below 10 hours, after which growth rate slows to a standstill but tolerance to cold temperatures remains in effect, allowing for winter harvest and overwintering for early spring harvest."

http://www.johnnyseeds.com/t-s...

For photoperiod (daylength) manipulation it has to be red light which is "measured" by a pigment in the leaves called phytochrome. Incandescents produce a lot of red light which is why they're commonly used for photoperiod control. (Actually plants really measure the length of the night but we still call it daylength). As little as 10 foot candles to the plants is enough to affect photoperiod, a 60 watt incandescent can do that, although you may need to space them out if covering a large area where one bulb isn't sufficient.

We have had a couple of days with sun, finally, and I already see a difference. The spinach is standing up nice and tall and looking happier. I've also been using red rope lights at night for several days, and that's been enough so the heater doesn't need to run. Wonder if those red lights are contributing something.
I agree with the comment about starting the spinach earlier. That is certainly a mistake I made this year--I'm learning how to garden. I hadn't factored in the shorter days. Next year I am starting things in September and then moving to the GH near Halloween. Also thinking it might not be productive to plant these things in Dec and Jan. On another note, what made me think I could ripen cherry tomatoes in there in November? The plant is doing great now that the catapillar problem is taken care of, but the fruit is as green as it was in October. Reflects my greenness at gardening--haha.

Are the rope lights incandescent or LED? If they're giving off enough heat to raise the greenhouse temperature then it sounds like incandescent. In that case, if they're giving off an appropriate amount/type of red light then they could be affecting daylength. In other words if they're on all night then the plants could be experiencing 24 hour days. I'm not sure what that would do to spinach, which flowers when the daylength is long, so hopefully their "upright" stance doesn't indicate bolting. Tomatoes don't like 24 hour lighting, FWIW.

You mentioned you'd had a heater on at night, that was one thing I asked about earlier because it can affect growth. The night temperature should be roughly 5 to 10 degrees F below the day temperature on a cloudy day, and around 13 to 15 degrees lower on a sunny day.

Carol, I think we all have to learn our local time-to-plant by trial and error.

I keep telling myself to keep records of when I sowed or transplanted, and how that worked, but even when I do write it down, I lose the notes!

You can get advice like "how many weeks before or after average last frost date", but that ignores things like late frosts, early warm spells, length of unsettled spring weather, how soon deadly summer heat is expected, the microclimate in your yard, and what exact varieties you are growing.

The advice that sounds best to me is "sequential plantings" where each crop gets sown several times, two weeks apart. Then you see whether "pushing the season" actually gains you much, and which dates gave the best results last year.

And try a different variety before giving up on a crop for your climate. They vary a lot!

And once you find an OP variety that does pretty well for you, that you like the taste of, start saving seeds from your best and tastiest plants. You'll automatically select for resistance to local pests, diseases and climactic limitations.

good info from everyone. Thanks !

My GH daytime temp is usually in the mid 70s. Night time is 62 to 65. That may drop a bit when we get the occasional 22 degree night.

The rope lights are incandescent. I've only been running them nights for the last 5 days or so but sounds like I will have to keep a close eye on that as the plants may get too much light. Think I will put them on a timer and maybe let them start running a few hours before dawn, when it's the coldest, and then off, as opposed to all night. That would then give them 12-14 hours or so a day when combined with daylight. @sooby I will pay more attention to the shift In Temp between night and day. Part of the problem may be our shifting weather between cloudy and sunny and I haven't made any changes to accommodate that.

@rickcorey great idea on the sequential plantings. Think I will do that and keep a log of what planted and when. Should yield some great info. I hate to give up so soon. I really want dinner from the greenhouse!

I will post again in a couple of weeks and let ya'll know how it's working out.