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Hi jpnightingale, Spinach is fussy and inconsistent in hydroponic systems like the TG... almost to the point of being not worth the effort (many commercial TG growers avoid it). Spinach is also notoriously difficult to germinate (temperature control and age of seeds is critical). If you still consider growing spinach in the TG a worthwhile investment in time and energy then you may find this information helpful:
How to Grow Spinach In Your Tower Garden:
* Spinach is a cool weather crop that lends itself well to the hydroponic realm only when properly cared for. It does not perform as well in higher temperatures. Prolonged warm temperatures will cause most varieties of spinach to bolt to seed, which basically ruins your crop. Spinach that has bolted is bitter.
* Temperature should never exceed 75 F at anytime during the growing process. Average day cycle temperatures of 65 - 70 F and average night time temperatures of 60 - 65 F will contribute to the best results, in quality and in producing a quick timely harvest.
* Spinach germinates best at temperatures between 60 and 75 degrees.
* For seeds that have not yet been germinated - store at 40 to 70 degrees F., cold stratification for a week or two prior to planting is a nifty little trick some growers use. Keep the seeds in the refrigerator for a few weeks before sowing them - it has the effect of hardening them and leads to a healthier plant.
* Seeds become less viable as they age, germination rates decline incredibly. Be sure to use seed that is packaged for the current growing season.
* Spinach typically takes 6-10 days to germinate.
* Resist the temptation to transfer spinach seedlings into the TG until you see roots exiting the rockwool cube (two weeks is typical).
OK, so the 60-75 degrees is the germination temp. What about being in the dark under a box vs: in any light? I have searched the docs for that answer. Have I missed it? I have placed in warm sunny window in the past which failed. Used the greenhouse with lights on for 14 hrs last winter which failed. These seeds are newly purchased at Phoenix conference so that shouldn't be a problem. If darkness is the answer, how much light/day once they germinate? Putting them in a window will be too warm.
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Hi jpnightingale, The purchase date of your seeds is irrelevant. What is critically important is the date stamp on the seed package. Old spinach seed does take longer to sprout so new seed is a really good idea. Many people have had great success with starting spinach seed in damp, folded paper towel in a new ziploc plastic bag (so, to answer your dark/light question: Dark). As the seeds germinate, transfer them to pre-soaked rockwool cubes (use tweezers). If the seed doesn't germinate well, a day or two in the refrigerator might help. Although spinach is one of those "special exceptions", you should be able to use most parts of my "generalized" seedling growing procedure once the spinach is in the rockwool cubes:
Best of luck! Discouraging to hear of your challenges. I have had success germinating spinach direct in rockwool (under Aerogarden Harvest lights but in the TG tray) as well as in the Aerogarden using the Seed Starting System plugs (can do 30 at a time); the latter come up faster, generally—were ready to transplant to TG on day 10; spinach sown direct in rockwool took almost a week longer to be ready. (When transplanting the AeroGarden Seed Starters in the TG I cut a soaked rockwool cube in two and sandwich the plug in-between.) Lights in the Aerogarden have been set to run 20 hrs a day. But once transplanted in my TG they've been growing outside on a deck.
I have been able to enjoy so far this season the varieties: Mustard Spinach (by American Seed), Bloomsdale Long Standing (by Burpee), and Salad Sensation Hybrid (by Burpee). All packed for 2016. The Bloomsdale and Mustard Spinach varieties I chose because they said they did well in heat. I have just sown direct from packet (stored inside a canister in a cool cupboard) to the rock wool or Aerogarden plugs; as well I recently got a Garden Tower 2 and I sowed spinach the second week of June direct to the soil. And those came right up too—2" tall now.