Even with years of marketing support from Popeye, spinach is often treated as a distasteful vegetable, forced on kids by well meaning parents just trying to get some vitamins into their offspring. I want you to give spinach another chance. Yes, it is super healthy for you, but that doesn't mean it has to taste bad! Add super easy to grow, and you can't go wrong with good old spinach.
Spinach (Spinacia oleracea) is a member of the Amaranthaceae family. It is related to many other vegetables that do well here (such as beets and swiss chard) and many grains (such as amaranth and quinoa). People have been growing spinach for around 2000 years and it is now grown all over the world. And, yes, it is absolutely chock full of nutrients:
an excellent source of vitamin K, vitamin A (in the form of carotenoids), manganese, folate, copper, vitamin B2, vitamin B6, vitamin E, calcium and vitamin C.
a very good source of zinc, dietary fiber, phosphorus, vitamin B1 and choline.
contains a unique and beneficial mixture of phytonutrients, as well as anti-oxidants, flavonoids and carotenoids.
it is also one of the best plant-based sources of iron and protein
only 7 calories per cup of raw spinach and 41 calories per cup of cooked spinach.
Why you should grow spinach
Good nutrition is motivation enough to grow spinach, but there are a few other reasons you should add it to your list must grow items. Most importantly, spinach likes it cool. And we tend to have lots of cool in our climate. It can be planted very early in the spring and can be harvested quite late into the fall, making for a long growing season. Spinach is usually the very first vegetable ready to harvest from the garden each year. It also grows crazy fast, allowing for a number of successive plantings each year. Lastly, spinach purchased from the store can be loaded with pesticides. In fact, the Environmental Working Group has spinach on its dirty dozen list as the second most contaminated produce in stores. Only strawberries have been found to have more. That is a great argument for growing your own spinach (and strawberries too)!
Growing spinach
Location
In the garden, spinach prefers well drained, rich soil full of organic matter. It will grow in full sun, as long as it is somewhat cool, or part shade. Spinach will bolt if it gets too hot (see below). Because it is such a quick grower, you can easily move successive planting locations to sunnier or shadier areas as the seasons progress. Growing in containers is an easy option for those with limited ground to grow in. Some varieties will develop a fairly long tap root if allowed to mature, so you either need to pick it when small (think baby spinach) and replant, or have a fairly large container. And don't forget about spinach in the winter months. Spinach is easy to grow indoors as it doesn't require a lot of light and it is fantastic grown as microgreens (see the article Sprouts, Shoots and Microgreens for more info).
Seeding
Spinach is best direct seeded in the garden. (It is a fast germinator and a poor transplanter, making starting indoors less successful.) See the article on direct seeding for a how-to. Seeds can be planted in spring as soon as the ground is workable. This means no longer frozen (at least as deep as needed to put the seeds in) and no longer soppy wet. Here in Calgary, that is usually mid to late April. Each year is different, so keep an eye on your chosen planting area to see when it is ready to go. Seeds will germinate once soil temperatures reach around 4 C. They will be okay hanging out in the soil, even through frost or snow, until it gets to that temperature. The seeds take about 7-14 days to emerge at ideal temperatures (24 C) and will be slower at cooler temperatures (about 3 weeks at 10 C). Anything above that 24 C and seeds often fail to germinate.
Seeds should be planted 1/2" deep and approximately 2-3 inches apart within a row, or 16 plants per square foot if using square foot gardening. You can always plant closer together or 2 seeds in each hole, and thin later to accommodate lower germination rates due to extreme temperatures or older seed. Most spinach seeds have a germination rate of around 65%, so over-seeding is not a bad idea. Check the germination rate on your seed packages to be sure. Water well throughout the growing season as spinach needs a fair amount of moisture to flourish.
Fall planting: I have also found success planting spinach in late fall, once temperatures are below germination temperature (consistently below +4 C). Seeds will overwinter in the ground and sprout in early spring, before they would if planted once the ground was workable. Leaves can be slightly tougher than normal, but I find it worth it for an earlier crop. Note that there are some years where this doesn't work, due to an especially tough winter. Give it a try!
Succession planting
Spinach has an average of 39 days to maturity (although there are varieties that take anywhere from 20 to 50 days). That is quick! We can take advantage of spinach's speed by growing more than one crop each year. This is called succession planting. One way to do this is to plant half of your intended spinach space, and then plant the remaining half about 2 weeks later. This way you don't have a huge amount of spinach all ready to be picked and eaten at the same time. The harvest period is spread out. There can be such a thing as too much spinach at one time! Another way to succession plant is to seed your spinach, let it grow, harvest all of it when mature, and then replant new seeds immediately in the same spot. We can do this a number of times in one year. I like to do a combination of the two, where I plant half the space, two weeks later plant the other half, then I immediately reseed once each half is harvested. Then I repeat. This way I have a constant supply of mature spinach throughout the year in a very small space.
If we use an estimate of 15 spinach plants eaten by each person in a year we can determine how much space we need. Using 16 plants per square foot, we only need around 4 square feet of space for a 4 person family. If we first plant April 22 (halfway between mid and late April) and count the number of days until our average first frost of September 15th (spinach will not survive frost) we get 146 growing days. If we have a variety that matures in 39 days, we can get almost 4 successive crops in one year by planting immediately after harvest. That means with succession planting, we only need 1-2 square feet of space for that family of 4. Sorry, I know that was fair amount of math but here is the key take away: succession planting allows you to have a consistent harvest throughout the year in a much smaller space. Check out the article on Crop Planning: Part 2 if you want to see how easy this is to figure out in a crop planning spreadsheet.
Companion planting
Spinach gets along with pretty much anything in the garden. It is perfect for squeezing in beside plants that will get either much taller or wider later in the year. For example, spinach grown on the shady side of tall, indeterminate tomatoes benefit from that cooling shade in the heat of summer when they are prone to bolting (see below). This goes for any tall vegetable garden plant too. Spinach planted next to space hogging squashes and melons can often be seeded, grown and harvested before the larger plant is in need of that space. Similarly, because spinach has most of its growth above ground, it can be more closely planted with crops that have most of their growth below ground, such as root crops. There is conflicting information out there for potatoes however. Many have noted that spinach can attract pests that harm potatoes, while others say they are great companions because of the space saving properties of a leaf crop and a root crop planted closely together. Personally, I have not grown them together as potatoes require hilling that makes growing anything directly beside them tough to do.
Another great companion for spinach is anything in the onion family (garlic, leeks, onions, etc). They may help by deterring pests repelled by the sulfur compounds found in them. Flea beetles, aphids and even rabbits tend to stay away from onions and may provide protection for susceptible crops, like spinach, planted beside them.
Strawberries and spinach are a classic pairing, both in the garden and on the table, although the benefits go mostly to the strawberries. They are easily interplanted with spinach and thought to benefit by having their fruit hidden from browsers.
Bolting
Bolting is what we call it when plants produce a flower stem, go into bloom, and then produce seeds. Heat in the soil triggers this process, and once it starts it is irreversible. Breaking the flower stem off will simply cause more stems to emerge. For spinach, bolting begins to occur at around 29 C and the hormonal change in the plant causes the leaves to become significantly more bitter. Once you see your plants grow a tall stem and begin to form flowers, it is time to harvest the entire plant. Pull it up and use it immediately. You can delay bolting by planting your spinach in part shade, instead of full sun areas, especially during the heat of mid summer. Shading your plants using shade cloth or adjacent tall plants can also help stave off bolting, at least for a bit longer. Another strategy is to grow spinach only in the cooler seasons: spring and fall. During mid summer, heat loving plants can be transplanted or seeded into that area instead. Some summers (and, sadly, this year is looking like one of them), we never really get enough heat to make bolting of spinach an issue.
Harvesting
Spinach can be picked and eaten at any size, from tiny sprouts (microgreens) to fully mature and just beginning to bolt. In terms of flavour, young small leaves taste the best. Think baby spinach. You can either harvest the entire plant by pulling it up by the roots and then removing the leaves, or you can harvest leaves bit by bit. Just like you do with kale, continually remove the larger leaves from the bottom of the plant as needed, leaving the rest of the plant to continue growing and producing new leaves. You can continue to do this until the plant begins to bolt, when it should be pulled up entirely.
Hard frost is usually the end of spinach growing season here in Calgary. Spinach will stop growing at 4 C, but will continue to be harvestable. Frost, however, will turn spinach leaves to mush. You can delay this by covering your plants with frost cloth or old bed sheets when there are frost warnings, but if we get a hard frost (four consecutive hours below -2 C without a cover) it is time to turn in the towel and pull them all. Keep an eye on the forecast. It's better to salvage what you have then have it all be unusable mush.
Seed saving
Most spinach varieties available to the home gardener are hybrids, as they have been bred specifically to bolt later and mature earlier. Seeds from hybrid plants will produce unpredictable plants. It may be a fun experiment to see what you get, but if you want a plant that is true to seed (is the same as your parent plant), you will need to collect seeds from open pollinated spinach plants. There are a few available, but you will have to purposefully search them out. Monstrueux de Viroflay is one open pollinated variety available from West Coast Seeds. If you would like to save seeds, keep a few healthy plants that are bolting in the ground and allow them to form seeds. Seeds are mature once they turn a tan brown colour with a solid, true white interior. Cut the plant at its base and hang upside down for 4-10 days to fully dry. Thresh seeds to remove and store in a cool, dry place. Spinach seeds will last for 2-4 years if kept in ideal conditions.
Pests
Spinach is a pretty easy to grow vegetable here in Calgary. Because we eat single leaves of the plant, any leaves that have been affected by pests can either be disposed of or the nasty parts of each leaf torn off. Very rarely are pests ever bad enough to affect an entire plant and make the whole thing inedible.
Slugs
Slugs cause the most damage to spinach in my garden, especially during really wet years like this one. Take a look after dark with a flashlight to confirm they are an issue for you. Silvery, slimy trails are another big indication of slugs. There are a number of ways to reduce slug and snail numbers in your garden:
Set up a bait trap. Beer in a small container set level to the ground is a good one. (Please don't waste your good beer on this. Cheap crappy beer only!) Empty orange halves work equally well. Slugs love yeast and all citrus. You will need to clean them out each morning. Even a board left on the top of the soil will act as a daytime hiding place for slugs and a good place for you to collect them in the morning. Collected slugs can be put in soapy water or squished.
Diatomaceous earth or ground up egg shells spread on the soil around your plants act as a barrier that slugs will not travel over (it cuts them up).
Copper also acts as a barrier to slugs (it gives them a bit of a shock). You can use copper mesh around each individual plant or pennies or copper tape around your entire raised bed (note that this will only keep new slugs out, not remove ones that are already in your beds). Any barriers must be continuous to be effective. Slugs will find a way around if it isn't.
Leaf miners
Leaf miners are the larvae of a type of sawfly. The flies lay their eggs into the leaves by making a small cut in the leaf. When hatched, the larvae eat the interior of the leaves. Often times you will see black spots in the browned sections that is the fracas (poop) of the larvae. Leaf miners rarely do large amounts of damage to spinach, but if you are worried, there are some actions you can take to reduce that damage. First is to use row covers to prevent the flies from laying the eggs in the first place. They should go on the moment you see the sprouts poking through the soil. Using row covers that still allow sunlight and moisture to penetrate are best. They can be found wherever gardening tools are sold. You can also let nature take care of the problem for you. Natural populations of predaceous non-stinging wasps occur naturally here. They will naturally reduce leafminer infestations and damage will be limited. This does require a bit of patience as well as tolerance for a small amount of damage (there needs to be some prey in order for predators to exist and stick around). It also means not using chemical pesticides, as these will kill the wasps we want to encourage.
Hail damage
This isn't really a pest, but it can completely shred your spinach crop in just minutes. The only way to prevent damage is to cover it up. Old bed sheets, cardboard boxes or whatever you can grab quickly to cover your garden will reduce damage. If your spinach does happen to succumb to hail, take a deep breath and know that spinach is very resilient and will come back! Clean up any completely ruined leaves and give it some time. You will be surprised how quickly it can recover.
Varieties
Spinach is generally grouped as either a savoy variety or a smooth variety. The spinach you buy at the grocery store is usually the smooth type. Commercial growers choose smooth varieties because they typically grow faster, grow more productively and are easier to clean. Conversely, savoy types have more crinkly leaves, do better in cool climates like ours, will keep longer, contain less oxalate and are more resistant to slugs. Savoy types are often preferred in both taste and texture to smooth types. There are also semi-savoy varieties now available that have the taste and texture of savoy and the easy cleaning of smooth. No matter which type you choose, it is always a good idea to go for a variety that has a higher ratio of leaf to stem. It is the leaf that is the yummy part, after all. Look for smaller varieties such as Tyee for containers.
Some good varieties that I have grown and am happy with include: Escalade (my favourite), Regiment (also really good), Renegade, Seaside (baby type good for containers) and Space (smooth type).
Spinach alternatives
There are many other greens that can be grown in our climate that are similar to spinach. People grow them because they may be far more heat tolerant (and therefore have better resistance to bolting) or have a slightly different flavour from spinach. Here are a few options:
Strawberry spinach has both edible leaves and edible red berries. It is also a beautiful addition to the garden. We are trying this one out next year. I will keep you updated.(https://www.rareseeds.com/store/vegetables/garden-berries/strawberry-spinach)
Swiss chard is a super easy to grow green with a flavor that is a cross between spinach and kale. It can taste quite minerally due to high iron content. I grow this one every year, in addition to spinach.
New Zealand spinach (Tetragonia) has succulent type leaves that are best eaten when young. It is another heat tolerant green.
Malabar spinach is a very heat tolerant green that grows as a vine. It can be slightly slimy in texture, like okra is.
Orach is also known as French spinach or mountain spinach. It is a salty tasting green that comes in red or green varieties and is heat tolerant. It will self seed readily if not dead headed.
Amaranth is a close relative of spinach that is usually grown as a grain. However, you can also harvest the young leaves to eat as a green (called Callaloo in the Caribbean).
Sorrel is a perennial green with yummy leaves that have a distinct lemony flavour.
Lamb's quarters (also known as goosefoot or pigweed) is a common weed here in Calgary that is also quite tasty. It is a close relative of spinach and is constantly popping up in my vegetable garden. Just pull them up as you see them and toss them in your next salad.
In the Kitchen
Spinach is best served fresh, straight from the garden if possible. Just pick, wash and dry. A salad spinner works best for me to dry the greens (look for one that spins both ways to get them as dry as possible). There are many good ones on the market. You can also put your wet greens in a tea towel, collect the ends together and whip the towel around in a circle. This is a fun thing to get your kids to do, but do it outside if you don't want a big wet mess in your kitchen! Washed spinach can be stored in a plastic bag in the fridge for 2-3 days. Add a paper towel to the inside of the bag to absorb any excess moisture and prevent rotting.
If you have an overabundance of greens that you need to preserve all at once, blanching and freezing is your best bet. Either stir-fry until wilted or dunk in boiling water for 1-2 minutes and drain. Pack the cooked spinach into resealable bags and remove as much air as possible. Freeze until needed and use within 1 year.
Recipes
Spinach is not only a standard in salads, it is also used as a healthy filler in everything from stews to pastries. I like to feel extra healthy during spinach season with a breakfast of sautéed spinach with garlic and butter, topped with a fried egg. Yummy! Here are some of the spinach recipes I use over and over again. (By the way, I will never list or print a recipe on this site that isn't one I absolutely love and use all the time.)
Spinach Salad (recipe coming soon)
Asian Ground Pork and Spinach (recipe coming soon)
Yummy gardening everyone!
References and Further Reading
Live Science (https://www.livescience.com/51324-spinach-nutrition.html) for all the details on the nutritional content of spinach.
Environmental Working Group 2020 dirty dozen list (https://www.ewg.org/foodnews/dirty-dozen.php)
West Coast Seeds (www.westcoastseeds.com) for seed sales and lots of spinach information, including companion planting.
Veseys Seeds (https://www.veseys.com/ca/) for seed sales.
Baker Creek Heirloom Seeds (https://www.rareseeds.com/) for specialty and hard to find heirloom seeds. Note this is an American company so check hardiness zones and days to maturity before selecting seeds.
Stacey Murphy (https://www.youtube.com/channel/UCK8WWphD0zYS4c5jsLOOOmg) for lots of videos on everything to do with growing food.
Chadwick Janet “The Busy Person’s Guide to Preserving Food” 1995, Storey Communications, Inc., Pownal, Vermont, USA