Spinach is an easy to grow crop that does well in areas where there is at least a month or so of cooler weather. It does well when grown indoors and can withstand frosts and light freezes.
If you're growing outdoors, plant your seeds as soon as the snow is gone and your soil can be worked. If you decide to sow in the fall, just mulch your soil over well and new growth should appear the following spring when temperatures begin to rise. A lot of gardeners prefer this method, and say that a "Fall crop" will usually taste better.
In rows 12 inches apart, space your seedlings 3 inches apart. After thinning, cover the plants with row covers to keep the pests away. Keep in mind that you may want to soak your seeds before planting to raise your germination rate. Spinach seeds can take quite a while to germinate.
Once your seedlings have emerged, be sure the soil is kept moist and add a high-nitrogen fertilizer such as blood meal or fish emulsion when seedlings are starting to mature and have reached a few inches high.
Read more: "How to Grow Organic Spinach from Seed"
Pro Tips for Growing Spinach & Other Greens Indoors
Try using several "two-bulb shop lights outfitted with full-spectrum grow lights. Suspend them by chains and s-hooks" -Margaret Boyles, Almanac.com
"Growing spinach indoors next to a window provides a more accessible and longer-season crop than growing it outdoors because the temperature can be controlled." -HomeGuides.SFGates.com
"Cover the trays and pots with a black plastic bag and place them in a warm (70F) spot. Often the top of the refrigerator is a good place to hasten germination since it stays consistently warm." -Garden.org
"Both leaf crops will need 6-8 hours of bright light. A bright room or an enclosed, sunny porch where temperatures will not dip down to freezing is a good place to place your pots. If needed, get a few grow lights to help supplement your plants. They are super easy and fast to set up." -WeekendGardener.net