Spinach Plant Growth Stages

We should probably all eat more vegetables, and spinach is one of the most nutrient-dense leafy greens. Plus, spinach (Spinacia oleracea) is easy to grow in the home garden, taking as little as five weeks to go from seed to harvest!

If you’ve ever grown lettuce, you already have what it takes to grow a good spinach crop. Both greens enjoy cool temperatures and similar soil conditions. I like to grow spinach and lettuce side by side if I have the space.

In this article, I’ll break down the spinach growth stages and how to take care of this leafy green in your garden.

Conditions for Growing Spinach

Spinach is relatively low-maintenance but has a few basic needs: cool temperatures, full or partial sun, well-draining soil, and a good source of nutrition.

Spinach is a fast-growing annual that grows best in USDA Zones 2 to 11. The best time to plant spinach can vary greatly depending on where you live — PennState Extension says that optimal growing temperatures are between about 50 and 60°F. 

Spring and fall are the most common growing times in cooler climates. Gardeners in warm climates typically grow spinach in the peak of winter. As a rule, spinach is pretty much never grown in the summertime. 

Spinach grows best with morning sun and afternoon shade. This setup ensures the spinach gets plenty of light but is less likely to experience heat stress during the day. 

Your spinach needs 1 to 1.5 inches of water per week. The soil should be consistently moist but never soggy — it’s best to water slightly several times per week versus all at once. Mulching around the base of the plant can help slow evaporation and keep the root system nice and cool.

With a mature size of about 12 inches tall and wide, spinach is a space-efficient crop for any garden. You can easily grow spinach in traditional beds, raised beds, and individual containers. (I even know of people who grow spinach hydroponically indoors!)

Conditions for Growing Spinach

Any plant that grows as quickly as spinach will need a lot of nutrition to thrive, especially in the form of nitrogen. I recommend amending the soil before planting and side-dressing every two weeks or as needed. 

Spinach Growth Rate

In peak conditions, spinach can grow an impressive 3 inches per week. However, the average growth rate is slightly slower.

Stunted growth usually indicates something wrong with the plant’s growing environment. It could be too hot or cold, or the spinach may get too little water. Another potential cause of slow growth is insufficient nutrients in the soil.

Growth Stages of Spinach

It doesn’t take much patience to grow a healthy spinach harvest. Most varieties mature in just 35 to 50 days after germination!

There are two basic types of spinach plants: smooth-leaved and savoy (crinkle-leaved). Some varieties are classified as semi-savoy, meaning they fall between the two types.

Each type of spinach contains countless varieties and cultivars — for example, ‘Bloomsdale’ is an extremely popular savoy variety. All spinach, regardless of its type, goes through the same basic growth phases.

You may have also heard of Malabar spinach. Despite the name, Malabar spinach (Basella alba) isn’t related to true spinach. Its life cycle and growth habits differ from the spinach in this article.

1. Seed Germination

Starting spinach from seed is generally a simple, no-fuss process. The seeds don’t need special care — i.e., stratification – to germinate and have a very high success rate as long as the seeds are sourced fresh.

Sprouting is only the very last step of germination. Instead, the bulk of the germination process happens inside the seed, completely out of sight. 

Spinach seeds need soil temperatures above 40°F to germinate. As soon as such conditions trigger germination, the seed starts absorbing moisture through the seed coat. Some growers choose to soak their seeds before planting to speed this step along.

Spinach seeds round
Credit Image: Amada44 by cc 3.0

The cells inside the spinach seed will then start rapidly dividing. This is the start of actual growth within the seed. 

Finally, the seed starts to sprout. The first structure to emerge is the radicle (primary root), followed by the hypocotyl (primary stem) and cotyledons (embryonic leaves). While the radicle typically goes down to anchor the seed into the soil, the hypocotyl and cotyledons naturally grow up through the soil’s surface.

For most gardeners, the emergence of the seed’s hypocotyl and cotyledons from the soil is the first sign of growth. Depending on the growing conditions, this can take anywhere from 5 to 30 days. (Note that temperatures at or just below 75°F tend to produce the fastest results.)

2. Seedling

Each spinach plant sprouts with two primitive leaves called cotyledons (we covered these briefly in the previous section). Cotyledons develop inside the seed’s embryo and provide a rich energy source throughout the germination and early seedling stages.

All leaves that follow the cotyledons are considered ‘true’ leaves. These are identical to the adult spinach foliage in form and function; they tend to be smaller during the seedling phase. 

Once the spinach seedling grows a few true leaves, don’t worry if the cotyledons shrivel or turn yellow. This is normal as the plant no longer needs the cotyledons to provide energy/

Since the life cycle of a spinach plant is so short, the seedling stage may only last about seven days or so. There’s no definitive end to this stage. One day, you’ll just check on your spinach plants and notice they look a bit more ‘grown up’ than the day before!

3. Vegetative Growth

Even after the spinach grows from the seedling phase, it focuses primarily on getting bigger and producing more leaves. The new leaves themselves should get bigger as the plant becomes more established.

Most spinach varieties grow as rosettes — all leaves originate from a short central stem. Unlike leafy greens like head lettuce or cabbage, the spinach rosette is loose and open.

This stage lasts at least 28 to 42 days. Harvesting spinach at the end of this growth stage is common, essentially cutting the plant’s natural life cycle short. If you let spinach continue growing (or experience an unexpected hot spell), flowering is next on the docket.

4. Flowering

Spinach plants have very small, yellow or green flowers. Male flowers form on spikes at the top of the plant. Female flowers form along the length of the plant where the stem branches.

This stage normally lasts between 14 and 21 days.

Spinach flowers in response to changing environmental conditions rather than a set number of days after planting. Most varieties start to flower when there are 10 to 14 hours of sunlight per day, and daily temperatures are above 75°F.

Spinach seeds Flowering

Premature flowering — before harvest time — is known as bolting. In spinach and other popular garden vegetables, bolting is almost always bad. While you can’t do much to prevent bolting, some cultivars are bred to be less prone to it.

The reason bolting is so dreaded is that it affects the flavor of the spinach leaves. Bolted spinach tastes very bitter and may have a tough, rubbery texture. You can still eat leaves of bolted spinach, but you probably won’t want to!

5. Pollination

Spinach is classified as a dioecious plant. Dioecious plants have either male or female flowers, but never both. You can tell whether a particular spinach plant is male or female by looking at the location of the flowers.

Few pollinators are attracted to spinach flowers. Instead, most plants are pollinated by the wind, spreading pollen from one spinach plant to adjacent ones.

Pollination can occur between spinach varieties. For gardeners interested in collecting seeds for the following year, keeping different varieties isolated from each other is important. A distance of at least 800 feet between varieties is recommended by Seed Savers Exchange but isn’t realistic for many home gardeners! You can experiment with physical barriers to prevent cross-pollination as well.

6. Seed Development

The one real benefit of letting your spinach go to flower is that it can produce viable seeds for future plantings. Remember that not all plants will produce seed. Only plants with female flowers will bear seed.

After pollination, clusters of seed pods form along the main stem. These clusters take the place of the female flowers. 

Depending on the average daily temperature, spinach seeds can start forming as early as 60 days after planting. Wait until the seeds are tan and dry before uprooting the plant. Let the seeds dry for about ten days before storing for next year.

When to Harvest Spinach

You can harvest spinach when the leaves are a decent size or about 6 inches long. Another good rule of thumb is to harvest when there are at least 5 leaves per plant. This stage is typically reached 40 to 50 days after sowing seeds.

There are a couple of ways to harvest spinach once the time comes. First, you could harvest the entire leaf bunch at once. However, most gardeners prefer to harvest just some leaves at a time to extend the harvest by several weeks.

If you opt for the latter approach, you can cut leaves 2 to 3 inches from the base of the plant or harvest only the outermost leaves. These two techniques permit new leaves to grow if the weather conditions remain nice and cool.

Harvesting Baby Spinach

The information above pertains to harvesting mature spinach. But baby spinach is also incredibly popular. The only difference is that baby spinach is harvested when the plant is immature.

Baby spinach is usually ready to harvest 20 to 30 days after planting. Leaves should be about 2 to 3 inches long before harvesting.

If you have enjoyed reading this article, here’s a link to Lettuce Plant Growth Stages that you may also find interesting.

FAQ Spinach Plant Growth Stages

Can you still eat bolted spinach?

Bolted spinach is generally perfectly fine to eat. The issue is that bolting turns the leaves bitter and rubbery, which many people find off-putting. Spinach that has just begun to bolt may be salvageable, but the quality will quickly drop.

How long does it take to grow spinach?

Most spinach takes 4 to 6 weeks to grow from seed to harvest. You can stagger new spinach plantings to extend the growing season by several weeks. Keep in mind that spinach needs cool weather to grow without bolting.

Citations

Website | + posts

Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.