10 Tips for Growing Spinach Indoors Any Time of Year
Grow spinach indoors all year long with these simple gardening tips.
Cold-hardy spinach plants are champions in cool spring and autumn gardens, but spinach notoriously bolts in summer heat and harsh winter weather often kills the plants. But by growing spinach indoors in pots, you can harvest homegrown spinach all year round.
While spinach grows beautifully outdoors in cool weather, growing this crop inside has a lot of perks. Not only does indoor cultivation allow you to grow spinach during winter, but it also helps prevent pests and bolting. And, of course, if you grow spinach on your windowsill, it will be much easier to harvest too.
Growing spinach indoors is very similar to caring for an indoor herb garden. All you need is the right balance of light, water, and a bit of fertilizer too. This guide will help you grow your own lush crop of spinach in any season right in your kitchen.
Related: The 9 Best Indoor Gardens of 2023 for Growing Delicious Herbs and Vegetables
Scott Little
1. Choose the right containers.
Spinach plants can grow in tight quarters and don’t need particularly deep soil, but choose pots that are at least 14 inches in diameter. A pot this size can hold about 3 or 4 spinach plants. Terracotta pots and planters are obvious choices for indoor gardens, but you can also cultivate spinach in grow bags. Just make sure that whatever container you choose has plenty of drainage holes to prevent soggy soil.
2. Use quality potting mix.
If you’re used to growing spinach in an outdoor garden, it can be tempting to use garden soil in your indoor pots, but this isn’t a good idea. When added to growing containers, garden soil tends not to drain well enough. Instead, choose a rich, well-draining potting mix for your spinach plants and consider amending it with a handful or two of compost or worm castings before you start planting.
Related: The 13 Best Potting Soils for Indoor and Outdoor Plants
3. Pick a bright location.
Spinach doesn’t need as much bright light as some other vegetables, which makes it easier to grow inside. However, spinach will still need to receive at least 4 to 6 hours of light daily to grow well and produce all of those luscious leaves. To ensure spinach receives enough light, locate your plants on a sunny windowsill or keep them under a bright grow light.
Related: The 12 Best Grow Lights to Help Your Plants Thrive in 2023
4. Follow planting instructions.
Indoor spinach can be grown from nursery started plants, but it’s typically easier to start with seeds. The seeds can be started at any time of the year and can even be sowed in succession every few weeks. For proper growth, spinach seeds should be planted a half-inch deep in planting holes spaced about 2 inches apart.
5. Use a heat mat.
Although spinach grows well in cool weather, seeds won’t germinate if temperatures are too chilly. This may not be a problem if you keep spinach in your home, but if you’re growing spinach in a garage or other outbuilding, you may want to add a heat mat beneath your plant pots to speed up germination rates. Spinach seeds that are kept between 40 and 75°F should germinate in about 5 days.
6. Water regularly.
Once you’ve planted your spinach seeds, you’ll want to water them regularly so that the soil stays moist but never soggy. When seeds are still young and delicate, you may want to water your pots with a mister bottle to avoid dislodging lightweight seeds. As spinach sprouts and begins to grow, water your plants when the top inch of soil feels dry and direct the stream of water towards the soil line to keep your spinach leaves dry and disease-free.
7. Thin out seedlings.
Spinach seedlings should be thinned out when they are a few inches tall and have grown one or two sets of true leaves. The idea is to select the healthiest plants and avoid overcrowded pots, which can lead to stunted growth and plant diseases. Thin out spinach seedlings so that they are spaced about 3 to 5 inches apart. And feel free to use the seedlings you remove as edible garnishes and microgreens.
8. Avoid excessive heat.
If you grow indoor spinach in winter, you won’t need to worry much about your plants getting too hot, although you’ll still want to keep your spinach away from space heaters. However, if you grow spinach indoors in summer, you may need to protect your plants from heat by moving them away from hot windows when temperatures climb. Remember, temperatures above 80°F cause spinach plants to bolt.
9. Apply fertilizer.
Indoor spinach needs less fertilizer than plants grown in the garden, but spinach crops will still produce more leaves if they’re grown in rich soil. Starting your spinach out in a quality potting mix that has been amended with compost is a good place to start, but you may still want to fertilize potted spinach plants throughout the growing season. For optimal growth, use a balanced, liquid organic fertilizer diluted to half strength and apply it once every 2 to 3 weeks from spring to fall.
10. Harvest frequently.
Indoor spinach is ready to harvest in about 35 to 45 days after planting. You can either harvest entire spinach plants all at once or you can clip away the oldest leaves towards the exterior of the plant and allow the younger leaves to continue to grow. Spinach will have the best flavor if you harvest leaves when they’re still tender, but the flavor of spinach begins to degrade when plants start flowering. If flowering occurs, pull up your spinach plants and sow new seeds to keep your indoor crop going strong.
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