I've never had any luck with spinach, but I DO have great luck with swiss chard! The green or gold is very tender and very much like spinach when young and tender.The rainbow seems to be tougher and have bigger ribs.
There is also a "fake" spinach, can't remember the name, that is very hardy. I'd like to find this out myself! LOL
Is it New Zealand spinach?

There are lots of "spinach" substitutes. Malabar spinach (Basella rubra), Vegetable amaranth/Chinese spinach (Amaranthus tricolor), Ceylon spinach (Basella alba), Okinawan spinach (Gynura crepioides), New Zealand spinach (Tetragonia tetragonoides) etc. As noted noted Swiis Chard and beet greens (Beta vulgaris) can be sustituted. Mustard spinach (Brassica rapa var. komatsuna) is also used as a substitute in some situations.
While no spinach (Spinacia oleracea) gets to be a big tall plant, some do better than others. Skookum, Hellcat, Teton, do pretty well for me.
{{gwi:117759}}

IME 'Tyee' And 'Harmony' are easy to grow, fairly large, and have a wide temperature tolerance.

Dan