Growing Spinach in Containers

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Spinach plant seedlings in a container with soil

 

Many gardeners find it difficult to grow Spinach but it's actually easy to grow in containers provided your climate strictly matches the temperature requirements of spinach, and if you can keep the soil moist at all times. Once you get this right, you can get your own unlimited supply of spinach in just 6 weeks.

 

Spinach germinates only between 45⁰ F to 68⁰ F (7°C to 20°C) with a day length of maximum 12 hours. Seedlings will bolt at 80 degrees F (26C), or if the day length is less. Fertilize every 20 days, and keep the soil always moist else (guess what) it will bolt if you let the soil dry out. 

 

If you don’t live in a climate that can fulfill the requirements of spinach, you can grow alternative heat-resistant spinach-like plants like malabar spinach, New Zealand spinach and mountain spinach.

 

Spinach General Information

Origin

Central and Western Asia

Common names

Palak (indian)

🌵Type

Leaf Vegetable

🌵Climate

Cool

🌡️Temperature

45⁰ F to 68⁰ F (7°C to 20°C)

🌼Growing season

Spring and Fall

💧Watering

Keep the soil always moist, else spinach will bolt.

☀️Light

Full Sun / Part shade

Soil

Rich, well draining and moist

40% sand, 40% coco peat, 20% compost

Fertilizer

Organic compost every 20 days

Container Size

6 inch deep

Propagation🌱

From seeds

Spacing

2 inches apart, or 9 seeds per square foot

Pick a Spinach Variety

Spinach can be broadly divided into two categories: summer cultivars and winter cultivars. Spinach is a cool weather crop, however, if you live in a warm tropical climate, there are some summer cultivars of spinach that you may successfully grow during summer. 

 

Spinach Variety

Features

Bloomsdale Longstanding

Heat tolerant spinach variety

Catalina

Heat tolerant spinach variety with a mild flavor, performs well in higher than ideal temperatures.

Indian Summer

Heat tolerant spinach variety that is slow to bolt and disease resistant.

Oceanside

Heat tolerant baby spinach variety that is slow to bolt.

Malabar spinach

It does not belong to the spinach family but looks and tastes like spinach. Thrives in tropical climates that reach 90 F (32 C) and beyond.

New Zealand spinach

This actually belongs to the fig-marigold family, that thrives in warm weather from 60° to 75° F (16-24° C).

Orach (mountain spinach)

Heat-tolerant warm weather alternative to spinach, it actually belongs to the flowering family of the amaranth family and used as leaf vegetable. Ideal growing temperature is 6 to 24°C. It has a salty, spinach-like taste. It's slower to bolt in warm conditions.

Growing from Seeds

For an under limited supply of spinach, sow the seeds every month.

Container size

Pick a wide container so you can easily space out spinach seeds. The container should be 6 inches deep. Space spinach seeds 2 inches apart, or 9 seeds per square foot. 

Sunlight☀️

Spinach bolts in warmer temperatures. Keep the plant in shade if the temperature reaches or exceeds 80°F (26°C). Use a light colored container so it does not absorb too much sunlight heat and keep the container and the soil cool.

 

In general, a winter spinach cultivar is placed in direct sun, while a summer spinach cultivar is placed under shade.

Ideal Growing Temperature🌡️

Spinach is a cool season crop so plant in the spring or fall when the temperatures are in the range of 45⁰ F to 68⁰ F (7°C to 20°C).

 

Ideal growing temperature for Spinach is between 50⁰ F to 60⁰ F (10°C to 15°C). Young seedlings can tolerate as low as 15⁰ F (-9°C). If the temperature is too hot for spinach; i.e. >=80°F (26°C), then move the container under a shaded area so it will reduce the temperature to a desirable range.

 

Water Requirements

Keep the soil moist all the time else spinach will bolt to produce seed, becoming bitter and inedible. Keep the leaves dry to avoid fungal diseases.

Soil

Spinach needs rich, well draining soil and moist soil, with a neutral or slightly acidic pH. So opt for a soil that is rich in compost or manure and does not hold water. One recommended soil mix is 40% sand, 40% coco peat, and 20% compost.

Fertilizer

Spinach is a heavy feeder. Fertilize every 20 days with a nitrogen-rich organic fertilizer like decomposed cow dung, vermicompost or leaf compost. Water thoroughly after adding the fertilizer.

Steps for Sowing spinach seeds

  1. Sow the spinach seeds in an 8 inch container with the soil, shallow tub, or raised bed ½ inch deep and 2 inches apart.
  2. Add a ¼ inch fine layer of potting mix. Do not sow the seeds too deep.
  3. Press it down lightly, firm the potting mix with the palm of your hand to create a smooth, even surface.
  4. Water the potting mix until it feels wet at a depth of 1 inch.
  5. Place the container in a partial shade for 10 days.
  6. Seeds will germinate in 8 to 10 days, depending on growing conditions.
  7. Your container will be full of tiny 3-4 inch spinach seedlings within 20 days. Now it's time to give it full sun.

How fast does Spinach grow

Here is a table that explains the rate of growth for Spinach that you can expect:

 

Event

No. of Days

Germination

8 to 10 days

3-4 inches long spinach

20 days

Spinach ready for Harvest

40 days

Second harvest

55 days

Spinach Bolting

Spinach will bolt because of all the following reasons:

  1. Soil dried out
  2. Temperature too hot for spinach; >=80°F (26°C)
  3. Day length is more than 12 hours
  4. Crowding seeds

Harvesting Spinach

You can harvest spinach at any time you like. Harvest when they reach a good size. If the spinach leaves are left on the stem for too long, they become bitter and lose. When harvesting spinach, cut the leaves at the base, leaving some stem so that more spinach can grow while you consume the first harvest. 

 

Spinach can be blanched or frozen for later use. Spinach also preserves very well in the refrigerator for a good 2 weeks.

 

Spinach contains oxalates that may increase the risk of kidney stones in some people. You can get rid of most of the oxalates by just scalding the spinach in boiling water and then running cold water over it (a process known as blanching). However, heat also destroys the beneficial vitamins in vegetables like vitamin A and C.

 

Nutritional Value

In a 100 gm reference, spinach is high in vitamin K (278% of Daily Value),  vitamin A, vitamin C, folate (B9) and Manganese with good amounts of other B Vitamins (B1, B2, B3, B6) and magnesium.

 

Spinach contains over 4 times the recommended daily intake of vitamin K. It is advised to minimize consumption of spinach (and other dark leafy greens) for those who are taking anticoagulant warfarin which acts by inhibiting vitamin k to avoid blunting the effect of warfarin.

 

Spinach contains Iron but due to oxalates which prevent absorption of iron unusable by the body. Furthermore, high levels of oxalates deplete the iron from the body. So people with iron deficiency should not rely on Spinach for their iron source.

 

Spinach contains calcium but due to oxalates, only 5% of it is absorbed by the body. So people with calcium deficiency should not rely on Spinach for their iron source

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