It is actually preferable that you put the spinach you are growing in the shade, simply because it tends to grow much better in cooler temperatures. When you make a point to closely monitor the conditions under which your spinach is growing, you will be able to increase the likelihood of it thriving once harvesting time comes around. Make sure that you put the spinach you are growing in moist soil as it does best in this kind. Too much heat and sunlight is very bad for spinach and can easily cost its growth to be inhibited.
By putting the spinach you are growing in rows in the shade you will be able to increase your chances of having more of it once it is time to harvest it. It is also recommended that you avoid planting your spinach in the summer months as it is far too hot and could damage your plants significantly. Spinach grows much better in a cool temperate climate so make sure you carefully decide when and how to plant it as well as in which type of soil.