Growing veg: spinach
Spinach is not a commonly grown crop. Most people grow leaf beet, commonly called spinach. It is also readily available in bags as a salad leaf, sold as baby spinach and almost always imported. I think you would have to be bordering in insanity to buy fresh spinach to cook because it famously cooks away to nothing. You can fill a saucepan to the top with spinach (and the same applied to leaf beet) and after a few minutes cooking it is a pathetic green lump at one side of the base! But I am not trying to put you off growing spinach.
Spinach is a cool-growing crop. It likes moist, cool growing conditions. If the weather is hot and dry the plants will quickly run to seed (see above with the variety ‘Bordeaux’ which is unusual for its red stems). This is not a huge issue because you can eat the shoots as they bolt, but it does mean that the useful life of the plants is over. I know I prattle on about sowing for succession but it really is worth sowing little and often. I would suggest sowing from March to May and then again in August and September but you can stretch the sowing time if growing in a polytunnel. Lots of modern kinds are resistant to mildew though I have never had that problem.
Because spinach is a short-lived crop I would pick the first leaves as salad leaves and as the plants start to bolt pick for cooking and if you miss the sweet spot and they get stringy you can juice them. Spinach reaches picking for salad stage very quickly and is a good patio crop especially as it will grow in shade. It is well worth a try.
The Biking Gardener 
Ha! I actually prefer it cooked. I know it is a waste of an otherwise good vegetable, but nonetheless, that is how I prefer it. I am none too keen on it fresh. There is a sort of lambsquarters here that I can cook like spinach. Because there is quite a bit of it, I do not mind that it cooks to a small volume of mush. (I am not supposed to eat too much spinach or lambsquarters though.) Unfortunately, it is not as good as real spinach, and is even worse fresh. I will eat it fresh if I must.
The oxalic acid issue can limit their use. And yes, lambsquarters or, as we tend to call the group fat hen and orache, are all good substitutes.
I have shady areas in our community garden and in my new-about-to-exist personal kitchen garden. I’m wondering if I can grow salad greens in the summer here in the shade? I’m in USA zone 7b, with highs up to 100F in the summer.
Or: what other herbs, edibles, or even annuals can I grow in the shade?
I haven’t been reading every veg entry like I did the annuals entries. But I do need to check some of them out! I’m new to growing veg so this is a great resource. Thank you for it!
Hello and thanks for looking at the blog. I hesitate to make suggestions since your climate is so different to here but I would definitely consider a shady spot for salads if you get that warm in summer. Water as well as shade will be critical. And as lots of salad plants will try to run to seed it will be important to sow regularly. Oakleaf and ‘lollo rosso’ type lettuce may do better than others and purslane may be a good choice since it copes with heat – though it can become a weed. Among herbs, coriander (cilantro) parsley, chives and mint will cope with light shade. Good luck with everything.