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A Guide To Growing Spinach From Seed

Read time: 9 minutes

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Spinach (Spinacia oleracea) is a nutrient-dense leafy green beloved for its versatility in the kitchen and ease of growth in the garden. Its vibrant, dark-green leaves are a testament to its rich nutritional content, offering a bountiful supply of vitamins and minerals.

Spinach’s flavor is best when the leaves are fresh and young. As the plant matures, the leaves can get slightly bitter and develop a leathery texture. I like to dehydrate the older leaves and grind them into powders or add them to soups.

Contents

Benefits and Disadvantages of Growing Spinach

Spinach is packed with vitamins A, C, and K, as well as minerals like iron and calcium. Growing your own spinach allows you to have fresh, organic produce at your fingertips, giving you a chance to savor the unrivaled taste of homegrown greens.

Growing spinach is a great for beginner gardeners because it’s relatively easy to cultivate. Spinach plants are hardy, and they can be grown in both spring and fall, making them a versatile choice for your garden.

However, like all plants, growing spinach isn’t without challenges. Spinach is a cool-weather crop and can bolt prematurely in warm temperatures, affecting its taste and productivity. It is also susceptible to certain pests and diseases.

Spinach leaf

Understanding Spinach's Growing Habits

Spinach is a cool-season crop that prefers temperatures between 35-75°F (2-24°C). It can be grown in both spring and fall, and in mild climates, it can even be grown throughout the winter. Spinach grows best when days are short and temperatures are cool.

A unique aspect of spinach is that it’s a cut and come again plant. This means you can keep picking the leaves as you need them, and the plant will continue to produce new ones.

How big does spinach get?

Spinach plants typically grow to a height of about 1 to 1.5 feet (30 to 45 cm) and can spread 1 foot (30 cm) wide. The size can vary depending on the specific variety of spinach and the growing conditions. However, the plant’s size isn’t as important as the size of the leaves when it comes to harvesting. Spinach leaves can be harvested when they’re just a couple of inches long for baby spinach, or allowed to grow to their full size, typically 3 to 5 inches long.

In a square foot gardening layout, you can grow about 9 spinach plants per square foot. Each plant should be spaced 3 to 4 inches apart.

Will spinach come back every year?

Spinach is an annual plant. This means it completes its entire lifecycle – from germination, through flowering and seed production, to death – in one year. Unlike perennials, annual plants do not come back year after year.

Spinach flowering
Spinach bolting in late spring

Choosing the Right Location

The location for your spinach plants should have good soil drainage and receive at least 6 hours of sunlight each day. Though spinach can tolerate partial shade, too much shade can reduce yield and encourage diseases. If you’re growing spinach in a pot or container, ensure it’s at least 6-8 inches deep to accommodate the root system.

Loamy or sandy soil is ideal because it allows water to drain effectively, preventing spinach’s roots from becoming waterlogged and prone to diseases like root rot. If your soil is heavy clay and drains poorly, consider improving it with organic matter or growing your spinach in raised beds or containers with a good quality potting mix.

Planting Spinach: Step by Step

Sowing the Seeds

Sow spinach seeds directly into your garden about 4 to 6 weeks before the last spring frost. Plant the seeds 1/2 inch deep and 2 – 3 inches apart. In a square foot garden layout, you can fit about 9 spinach plants per square.

Spinach seeds on a table

Caring for the Seedlings

After sowing, water the seeds lightly. Spinach seeds need moisture to germinate, so keep the soil consistently moist but not waterlogged.

Once the seedlings have sprouted and have at least two true leaves, thin them to stand 4 to 6 inches apart.

Spinach seeds typically germinate between 5 to 14 days after planting, depending on the soil temperature and the variety of spinach. These plants prefers cooler temperatures for germination. The optimal soil temperature for their germination is between 50°F (10°C) and 75°F (24°C). However, spinach seeds can germinate in temperatures as low as 35°F (1.7°C).

Spinach sprouts

Transplanting the Seedlings

Spinach can be started indoors to get a jump start on the growing season, especially in areas with short springs. Spinach seedlings are ready to be moved outdoors when they have at least 2-3 true leaves, which usually happens a few weeks after germination. However, before transplanting the seedlings outdoors, they need to be hardened off.

Hardening off is a process of acclimating indoor-grown plants to outdoor conditions over a period of about a week or two. Start by putting the seedlings outside in a sheltered location for a few hours a day, gradually increasing the time they spend outdoors and the amount of sunlight they receive.

Dig a hole in the prepared soil, making it deep enough to accommodate the root system of the seedling. Gently remove the seedling from its container, being careful not to damage the roots. Place the seedling in the hole, ensuring that the top of the root ball is level with the soil surface. Backfill the hole with soil and firm it gently around the base of the plant.

Use a watering can or hose with a gentle spray to thoroughly water the area around the base of the plants. Be careful not to wash away the soil or damage the tender seedlings with a strong stream of water.

The process of transplanting can be somewhat stressful for plants, as it often involves some root disturbance. Watering helps to settle the soil around the roots, eliminating air pockets and ensuring that the roots are in good contact with the soil. This helps the plants to recover more quickly and begin growing in their new location.

Spinach leaves in a basket on the ground

Aftercare

In the days following transplanting, keep an eye on the seedlings and water regularly, especially if the weather is dry. The goal is to keep the soil evenly moist but not soggy. Over time, as the plants establish and grow larger, you can gradually reduce watering frequency and allow the top inch of soil to dry out between waterings.

Add mulch around the base of the seedlings to help conserve moisture, suppress weeds, and regulate soil temperature.

Caring for Your Spinach

Maintaining your spinach plants involves regular watering, weeding, and fertilizing. Spinach needs an evenly moist soil, but the frequency of watering will depend on your soil type and climate. A good rule of thumb is to water once the top inch of soil feels dry to the touch.

Remember to weed your garden regularly to reduce competition for nutrients and light.

Apply a balanced vegetable fertilizer (such as a 10-10-10) or a nitrogen-rich organic fertilizer, like fish emulsion, every 2-3 weeks. Follow the application instructions on the fertilizer package.

If you’re growing spinach for a continuous harvest, consider giving the plants a little boost with some more nitrogen-rich fertilizer after each major harvest to encourage new leaf growth.

Harvesting Spinach

Your spinach is ready to pick when leaves are large enough to eat – usually when they are about 3 to 5 inches long. To harvest, simply cut the outer leaves off at the base of the plant, leaving the center of the plant intact for continued growth. This way, your spinach will keep growing even after you pick it, providing a continuous harvest.

Washed spinach leaves in a bowl

The best time to harvest spinach, and most other vegetables, is in the early morning. After a night of rest, plants are full of moisture and at their crispest. Also, the cooler morning temperatures help keep the leaves from wilting.

When you harvest in the morning, the spinach hasn’t yet been stressed by the heat of the day, so it will be fresh and tender. It’s also a good idea to harvest before the sun is shining directly on the leaves, as heat can cause the leaves to wilt quickly after they’ve been cut.

If you can’t harvest in the morning, the next best time is in the cool of the evening. However, keep in mind that the leaves will have lost some of their moisture to the heat of the day, so they may not be quite as crisp as they would be in the morning.

After harvesting, if you’re not using the spinach immediately, store it in the refrigerator to keep it fresh. You can rinse it and spin it dry, then store it in a plastic bag or container in the crisper drawer. A little bit of moisture left on the leaves will help keep them fresh, but too much can promote rot, so it’s a balance. Use the spinach within a week for the best quality.

spinach leaves on a dehydrator tray

Propagation and Multiplication

Spinach can be easily grown from seed. The plants can also self-seed under favorable conditions. After the growing season, allow some of your mature spinach plants to bolt and set seed. These seeds can be collected and saved for planting in the next season, or they may self-sow, giving you new plants the following year.

Common Problems and Solutions

While spinach is relatively easy to grow, it can be affected by certain pests and diseases. Leaf miners, aphids, and slugs are common pests that can damage your spinach crop. These can usually be controlled by handpicking or using row covers.

My spinach plants are most affected by leaf miners. I check the undersides of the leaves every morning or evening and just wipe off the little white eggs.

Diseases that affect spinach include downy mildew and white rust. To prevent these, ensure good air circulation around your plants, avoid overwatering, and practice crop rotation.

Bolting, or premature seeding, is another common issue when growing spinach. This usually happens when the weather gets too hot or the plants experience stress. To prevent bolting, ensure your plants are well-watered and get some afternoon shade during hot days.

I like to companion plant my spinach with climbing peas. As the weather warms and the peas begin to grow taller and fill out, they provide some afternoon shade for the spinach plants, potentially extending their productive period by protecting them from the heat of the sun. This method can be particularly beneficial in warmer climates or during unusually hot weather.

Spinach in the garden bed

Downy Mildew: Downy mildew is a fungal disease that can affect spinach and other plants, causing yellowing, stunted growth, and a white, fluffy growth on the undersides of leaves. It spreads through airborne spores that are released from infected plants. These spores require moist conditions to germinate and infect new plant tissues.

To prevent downy mildew, provide adequate spacing between plants to promote good air circulation, water plants at soil level early in the day. Remove and destroy any diseased leaves.

spinach plants in soil

White Rust: White rust is another fungal disease that can affect spinach plants, among other cruciferous crops. It is caused by the pathogen Albugo candida, and it primarily affects the leaves, stems, and flower parts of the plant. The most effective spinach white rust treatment is prevention.

White rust initially appears as small, raised, white or pale yellow pustules or blisters on the undersides of spinach leaves. Over time, these pustules can grow and become more prominent. As the disease progresses, the affected areas can develop a powdery or mealy appearance due to the release of spores. Severe infections can lead to leaf distortion, stunting, and reduced plant vigor.

If your plants become infected with white rust, practice crop rotation by avoiding planting spinach or other cruciferous crops in the same location for at least three years. This helps break the disease cycle and reduces the chances of reinfection.

Remove and destroy infected plant debris to minimize the spread of the disease. Avoid overhead watering, as it can create an environment conducive to disease development.

Remember, the key to dealing with any plant issue is early detection. Regularly check your spinach plants for signs of pests, stress or disease, and you’ll be well equipped to keep them healthy and thriving.

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References

1. Fishburn. Spring Greens | Illinois Extension | UIUC. Published June 3, 2020. https://extension.illinois.edu/blogs/prairies-perennials/2020-06-03-spring-greens
2. Kandel SL, Mou B, Shishkoff N, Shi A, Subbarao KV, Klosterman SJ. Spinach Downy Mildew: Advances in Our Understanding of the Disease Cycle and Prospects for Disease Management. Plant Disease. 2019;103(5):791-803. doi:10.1094/PDIS-10-18-1720-FE
3. Koike S, Becker J, Smith R, Fennimore S, LeStrange M. UC IPM Pest Management Guidelines: Spinach. UC ANR Publication 3467. https://ipm.ucanr.edu/agriculture/spinach/
4. The Editors. Spinach: Planting, Growing, and Harvesting Spinach Plants | The Old Farmer’s Almanac. Published May 3, 2022. https://www.almanac.com/plant/spinach

Hello and welcome! My name is Kate and I am an herbalist and backyard farmer. If you are a beginner herbalist or just looking for information on plants, I write about gardening, natural remedies, and herbalism.

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