Harvesting & storing spinach

Once your spinach is thriving, you can look forward to a plentiful harvest. Find out everything you need to know about the timing and steps for harvesting here.

If you grow spinach (Spinacia oleracea) in your garden, you will not have to wait long to see the results. It only takes about six to eight weeks for the spinach to be ready for harvest. Read on to find out how to harvest spinach as well as how to store it.

Harvesting spinach

One of the great advantages of spinach is that it is ready to be harvested in no time at all, and it can be harvested several times. When the leaves are about 4 cm long, they can be cut off and enjoyed as baby leaf spinach. These small, tender greens have a mild taste and are perfect for eating raw, for example in a salad. If you do not plan on eating your spinach raw, it is better to let it grow for six to eight weeks to get the largest possible leaves.

When to harvest spinach?

Spinach can be grown most of the year, which is why it is almost always in season. Only in the winter, from November to March, is spinach dormant and not harvested.

When to harvest spinach depends on when it is sown. Spinach harvesting typically begins after two to three months of growth. The timeline is also influenced by the season in which spinach is sown. The longer and warmer the days are, the faster spinach grows and the sooner it can be harvested. Keep a close eye on your plants, though − warm summer days can also lead to spinach bolting, making the leaves inedible more quickly. You can also find more information on growing spinach here.

There is a risk that nitrate will accumulate in the spinach leaves and become harmful. However, the amounts found in plants are generally only dangerous to small children.

The nitrate levels in spinach also have to do with the time of day it is harvested. In the morning, the nitrate content is higher than in the late afternoon and evening. This has to do with light exposure − photosynthesis has been proven to lower the levels of nitrate in spinach leaves.

Tip: Fertilisers and the soil’s nutrient content also have an impact on the amount of nitrate in the leafy vegetable. Some fertilisers are meant to make nitrogen quickly available to plants, which can lead to a nitrate build-up in spinach. However, since spinach needs nutrients, do not completely avoid fertilising. We recommend using our Plantura Tomato Food − its mainly organic composition slowly releases nitrogen to the soil, and, along with its nitrogen-potassium ratio of 4 to 8, the risk of nitrogen overfertilisation is decidedly reduced. To top it off, our fertilisers are 100 % animal-free. Nevertheless, it is best to stop fertilising your spinach at least three weeks before harvest.

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Bolted spinach: can it still be harvested?

Whether you can still eat the leaves of flowering spinach depends on their nitrate and oxalic acid content. These depend on factors such as fertilisation, nutrient reserves in the soil, variety, season, exposure and age of the specimen. This makes it difficult to say whether the leaves of bolted spinach are safe to eat. In any case, the leaves of flowering spinach usually taste bitter, making them undesirable in the kitchen.

How to harvest spinach?

There are a few ways to harvest spinach. Knowing how often you would like to harvest your spinach will help you decide which method is best for you:

1. Cut off all the leaves around the centre with a sharp knife. Done properly, and with care, the centre will sprout again, and the plant can be harvested up to four times.
2. Pull out the entire spinach plant, including the tasty spinach root. You can do this at the last harvest or earlier if you no longer wish to harvest more spinach.
3. Pick individual spinach leaves. This way you can harvest spinach continuously over a long period of time, but you only get a small amount each time. This option is also very time-consuming.

Does spinach grow back?

Whether spinach will grow back after it has been cut depends on how it was harvested. If you have only picked individual leaves or made sure to leave the centre of the plant intact when harvesting, your spinach should grow back. However, if you pull out the whole plant, including the roots, it will not regrow.

In short, the less you stress and weaken the spinach plant during harvest, the longer you can harvest it.

Tip: It is not only spinach that grows back when cut with care. Many other vegetable scraps that you would normally throw away can also be replanted and regrown.

Storing and preserving spinach

Fresh spinach has a very short shelf life, so it should be eaten or prepared for preserving promptly. Spinach can be kept in the fridge for up to two days. The ideal storage temperature is 0 to 1 °C. This applies to both spinach leaves and the root. Fresh spinach is best stored wrapped in a damp tea towel. To preserve spinach longer, you will need to freeze or blanch it.

How to store spinach?

The easiest way to keep spinach fresher for longer is to freeze it. However, you can cook and purée spinach and store it in canning jars or make it into a spread or pesto.

Freezing spinach

You can either freeze spinach directly after harvesting or blanch it first. Blanching spinach lowers the nitrate content and ensures that the flavour and colour are preserved. If you want to freeze fresh spinach leaves, wash them thoroughly before freezing to remove any soil.

Blanching spinach

Before blanching your spinach harvest, sort and wash it. Then, place it in a colander and blanch it in boiling water for a few minutes. Meanwhile, fill a bowl with iced water. After blanching, place the spinach in the iced water for about 10 seconds to stop the cooking process. Remove the spinach from the water, and carefully squeeze out any excess water before putting the spinach into freezer bags. This will make it less mushy when later thawed out. Also, before putting the spinach in the freezer, allow it to chill in the fridge. This also applies to cooked spinach: you can freeze it in the same manner, but let it cool down in the fridge first before putting it in the freezer.

How to freeze spinach?

• Wash the spinach and blanch it if desired
• After blanching, place the spinach in iced water for 10 seconds
• Squeeze out excess water, let it cool and put it in a freezer bag

Spinach that has already been cooked can also be frozen after it has cooled down.

Preparation and use

When preparing spinach, always clean it thoroughly to remove sand and soil from the stems. Many recipes call for spinach to be sautéed with a little water and then reduced.

Can spinach be eaten raw?

Most people can eat raw spinach leaves without a second thought. However, if you have small children, be careful because the amount of nitrite can be harmful to them. Spinach can also be problematic for persons who are prone to kidney and bladder stones, as foods containing oxalic acid increase the risk of their formation. You can cook spinach or prepare it together with calcium-rich foods such as cream or milk to lower the oxalic acid concentration. In addition, spinach usually contains less oxalic acid in autumn and winter than it does in summer.

What to do when spinach tastes bitter?

Spinach flavour varies depending on variety, location, and season, among other factors. Environmental factors such as extreme heat or drought can stress the spinach plant, causing it to store more bitter substances. When spinach bolts, this is extremely common. To avoid bitter spinach, choose a variety and location that matches the season − grow autumn spinach in autumn, not in summer, and vice versa.

Keep in mind that baby spinach tastes sweeter, while older spinach is more bitter. And the longer you cook it, the more bitter it becomes, so a quick blanch will give you a more pleasant flavour.

Finally, seasoning can counteract a slightly bitter taste of spinach. Try adding a bit of lemon juice.

Is it OK to reheat spinach?

The old rule about not reheating spinach is not entirely wrong. However, it is from a time when refrigerators were smaller and less common. If you leave cooked spinach at room temperature for a day, bacteria will convert the nitrate and make it unsafe to eat. To avoid this, always store cooked spinach in the refrigerator, where the cold temperatures delay the growth of bacteria. This way, the spinach can still be reheated a few days later without a problem.

Nutritional value of spinach

What makes spinach good for you? Spinach is high in many vitamins and minerals. It is rich in vitamins B and C, as well as provitamin A. The plant also contains minerals such as calcium, potassium and iron.

The iron content of spinach is a commonly discussed topic. In fact, with about 3.5 to 4 mg of iron per 100 g of fresh spinach, it is one of the vegetables containing the most iron. However, there are other foods with a much higher iron content such as liver, legumes and some nuts. Also, iron from plant sources is not as easily absorbed by our intestines as iron from animal sources. Combine spinach with vitamin C-rich foods like peppers to increase iron absorption. A squeeze of lemon juice also helps.

Although calcium is abundant in spinach, its absorption is hampered by oxalic acid. Oxalic acid binds to calcium, making it less bioavailable. To counteract this, heat up the spinach to reduce the oxalic acid content.

Spinach generally has a good impact on our health. Several studies have found that spinach possesses antioxidant and anti-inflammatory properties, among other benefits.

If you are interested in trying different types of spinach next season, get an overview here in our article on spinach varieties.