Guide to growing spinach

Spinach is one of my favorite things to grow in the kitchen garden. Not only is it easy to grow, but I love tossing garden-fresh spinach leaves into my salads and green smoothies for a flavor and nutrition boost.

Spinach is a member of the Amaranth plant family, which also includes beets and swiss chard—all foods that are chockfull of antioxidants, vitamins, and tons of fiber. 

Though spinach has become increasingly popular in the 21st century, you may be concerned to learn it ranks on the Dirty Dozen, a list of the top 12 vegetables and fruits that are typically farmed with high rates of pesticides, herbicides, and synthetic materials. The best way to ensure you're not ingesting stuff you don't want in your body is to grow your own spinach.

Fortunately, that's really easy to do! Here's your complete guide to growing organic spinach.

Spinach growing requirements & conditions

Overall, spinach is a fairly easy plant to grow. Like all plants, it does have certain conditions under which it prefers to be grown, and you can keep your plants happy and producing leaf after leaf for you if you keep the following in mind.

season

Spinach is a cool season plant. If your temperatures will rise above 80 degrees in the next two months, consider growing your spinach indoors or look for more heat-resistant varieties.

soil

Spinach loves to grow in a sandy loam soil that provides good drainage. This leafy green hates to have its roots stay wet for long periods of time.

sunlight

Spinach needs at least four hours of sunlight a day to grow. If the temperature will spike above 80 degrees, spinach benefits from shade during the hotter parts of the day.

fertilizer

Before you plant spinach in your garden, add a fresh layer of compost. Organic matter like compost will provide most of the nutrition that spinach needs to produce healthy green leaves. Unlike lettuce plants, however, spinach benefits from a bit of a nutritional boost as it matures. Look for organic fertilizers high in nitrogen to promote healthy leaf growth.

water

Water is crucial to germination of spinach seeds, and after sprouting, spinach seedlings need consistent moisture. Watering lightly every day or every other day will ensure the soil stays moist but is never too wet or too dry.

Does spinach need full sun?

While spinach grows best in full sun, it will continue to grow and produce leaves with just four to six hours of sunlight a day. If you're using artificial lights (which are not the same as the sun), give your spinach plants eight to ten hours of light per day.

When to start spinach

Spinach loves cool weather. Its ideal temperatures range between 45 and 75 degrees, but spinach thrives when daytime temps climb no higher than the 60s. Spinach can even handle a bit of frost.

You can begin sowing your spinach seeds directly in the soil outside starting about six weeks before your last expected frost date.

Spinach grows so quickly that I typically prefer to start it directly in the garden and save my seed starting trays for bigger plants that take a longer time to reach maturity, but you can also start your spinach seeds indoors if you'd like. (Read more on when to start seeds indoors.)

Growing spinach in fall and spring

Up here in Chicago, I grow spinach during my two cool seasons, one in the spring and one in the fall. I look forward to all the lettuces and leafy greens I can soon grow during the spring when it's deep winter outside.

If you're starting spinach seeds in the late summer in anticipation of your upcoming fall cool season, it's recommended to place the seeds inside a damp paper towel and keep them in the fridge in a plastic bag for four to five days before sowing them (to mimic cool weather and help speed germination).

The spinach I plant in the spring usually lasts until mid-summer, when the temperatures rise above 80 degrees.

Growing spinach in winter

If you live somewhere with milder winters, the best time for you to grow spinach and other leafy greens is actually over the winter during your cool season.

For those in colder climates, protect your spinach with cold frames, frost cloth, or floating row covers to prolong the plant's time in your garden. Again, spinach can handle light frost.

How to start growing spinach

There are actually three different types of spinach, so you can really broaden your spinach horizons by growing your own from seed. Smooth spinach is the most popular variety sold at grocery stores, mostly because it's the easiest to clean. You can also grow savoy spinach, which is bumpy, and semi savoy spinach.

You can start growing spinach from seed or buy plants from a local nursery.

Growing spinach from seed

Spinach seeds are tiny, but it's worth it to take the time to spread them out a bit as you're sowing the seeds to prevent having to thin them later once too many seeds come up close together.

Spinach seeds should be sown pretty shallowly at about half an inch to three quarters of an inch deep. Make sure to keep the soil evenly moist until seeds germinate (which typically takes about seven to 14 days) and are well established.

Once seedlings have developed several sets of leaves, thin if needed so that you only have one plant every three to four inches. Thin plants by using a clean pair of scissors to cut extra seedlings at their base, just above the soil. Whatever you thin can be used like a microgreen and tossed onto a salad.

Spinach grows super fast, taking only 40 to 45 days to reach maturity. Depending on the variety you're growing, you can begin to harvest leaves after 25 to 40 days. Harvest leaves while they're smaller for "baby spinach."

Harvest older, outer leaves from each plant frequently to maintain good air flow between your plants and prevent disease and pests.

If you'll continue to enjoy a couple more months of cool weather, sow another batch of spinach seeds for continuous harvests.

Growing spinach in containers

Thanks to its small root system and size, it's easy to grow your own spinach in a container. If you're not ready to commit to a full raised bed kitchen garden, growing spinach in a container is the perfect introduction to growing a little bit of your own delicious food.

Look for a container that's at least six inches deep, though I recommend going for one that's a foot deep and at least a foot wide so that you have enough leaves to fill a salad bowl. Also look for a container made from natural materials such as cedar, steel, and terra cotta clay.

If your container doesn't already have good drainage holes in the bottom, make sure to add some with a drill (aim for at least one drainage hole for every square foot of your planter). Spinach plants really dislike sitting in extra water.

You can start from seed or buy plants from a local nursery to fill your container. You can grow just spinach or mix in lettuce plants, marigolds, or parsley—all plants that like similar growing conditions to spinach.

The great thing about growing your spinach in a container is that you can move the container around to follow the sunlight. During the colder months, you can let your spinach plants get more hours of light because the sun is further away and the temperatures are lower. 

Because soil in a container dries out much faster than soil in a raised bed, make sure to check the moisture level every day to be sure the soil isn't too dry or too wet. 

Explore our favorite containers for growing spinach and other salad greens, or find the step by step to build your own steel tub planter with wheels for easy moving.

Growing spinach in raised beds

When the weather cools, I look forward to turning some space in my raised beds completely over to salad plants like spinach, romaine, and Rocky Top Mix from Baker Creek. While I also grow salad greens in containers, I don't have to worry about them being over- and under-watered quite as much in my raised beds. The extra root space in a raised bed tends to make plants more forgiving of conditions.

The one disadvantage of raised beds compared to containers is that I can't easily move my raised beds around to get just the right soft light that salad greens love or bring them inside if the day grows too warm.

Here's how you can create a super simple salad box in a small area of your backyard if you don't want to commit too much raised bed space to your spinach plants.

Growing spinach indoors

Thanks to modern technology (or a bright window sill) we can grow herbs, microgreens, lettuce plants, and spinach indoors and enjoy garden-fresh greens year round. Bonus, you don't have to worry about garden pests!

When it's too hot or cold outdoors for your spinach plants to thrive, here's how to grow your spinach indoors.

Pick a sunny spot on a window sill or purchase a full-spectrum LED grow light.

Start your seeds indoors the same way you would other seeds. Here are the supplies you'll need, including organic seed starting mix, grow lights, and seed starting trays.

Keep your trays in a room that stays between 65 and 70 degrees. Check your soil daily and keep it consistently moist but not soggy.

Maneuver your light source to be six inches above your seed tray once the spinach seedlings have their first set of leaves, and leave the lights on for 14 to 16 hours a day. You can then reduce to eight to ten hours per day once the plants have matured. Seedlings like having their light source close by, but anything closer than six inches can burn them. Make sure to raise your light source as plants grow.

Once your seedlings are ready to be transferred, move them into pots that are at least four inches wide. Fill these pots with a mix of potting soil and compost.

Growing spinach tips

Instead of giving spinach plants a deep watering once a week as you might other plants, consider watering spinach a little every single day or every other day to keep the soil moist but not soaking. Spinach plants really hate sitting in water, plus their roots are short and can't reach deep into the soil for water.

Grow your spinach when you have a period of at least eight to 12 weeks of temperatures mostly between 45 and 75 degrees, but don't stress if a little frost comes your way.

If your temperatures are staying fairly low, you can do what we call successive planting to get a continuous supply of fresh spinach, again and again. All you have to do is sow another round of spinach seeds in a free space in your garden a couple weeks after your last round.

Give your spinach plants some afternoon shade whenever temperatures exceed 80 degrees.

Growing spinach problems

Here are some common problems gardeners face when growing spinach and potential solutions.

Spinach not producing lots of leaves

This is most likely because the spinach did not receive enough sunlight or feel it had enough space in the garden. Make sure spinach receives four to six hours of sun per day.

If spinach seedlings are growing too closely together, thin them by cutting the base of less-robust seedlings just above soil level with scissors. Aim for one plant every three to four inches. As spinach plants grow, harvest the older, outer leaves often to ensure the plants have access to resources they need like sunlight and air flow.

Pests attacking spinach

Spinach can occasionally fall prey to aphids or leaf miners. If pests are attacking your spinach leaves, first prune away any leaves with holes or discoloration. If the pest issue continues, treat the leaves with castile soap.

The best way to protect your plants from pests is by working on the offensive. Learn more about the simple mesh barrier I put between my appetizing leafy greens and any critters that want to snack on them.

Spinach growing tall

When your spinach plant suddenly develops a thicker main stalk, increases in height, and starts growing more angular leaves (pictured above), your plant is doing something called bolting. That just means it's nearing the end of its life cycle and focusing its energy on seed production.

As soon as your spinach plant begins to feel stress—whether it’s because the weather’s changed, the plant has run out of space to reach its full maturity, or it’s used up the nutrients in the soil—it will make its only concern how to ensure the survival of its kind into the next growing season. That's good news for you if you want to save your own seeds and bad news for you if you want more delicious leaves.

Prolong the plant's remaining time in your garden by harvesting the outer leaves frequently and giving it some shade in the afternoons. The leaves are perfectly fine to eat until you find them too bitter or rubbery.

Learn more about bolting spinach.

Growing spinach year round

You probably don't live in a place that has ideal outdoor growing conditions for spinach 365 days of the year. But thanks to frost protection in the winter and artificial lights for indoor growing in the summer, it's more than possible to grow your own spinach all 12 months.

If you can't grow your own and if spinach is not in season, I encourage you to wait until cool weather returns. Most of our spinach in the United States is grown in California in the summer, spring, and fall, and then Arizona in the winter. Trucking spinach across the country to ensure grocery store shelves are always stocked with plastic bags and boxes is part of our modern food system problems.

Enjoy as much spinach as possible when it can be grown near you and purchased at the farmers' market.

Even better, grow your own year round supply! Once you taste the difference between store-bought and homegrown spinach, you just might be inspired to never stop growing your own delicious gourmet spinach!