Can You Grow Vegetables Indoors in the Winter?

Like some plants in winter, the Laidback Gardener team will go “dormant” during the month of January, to replenish its strength for the coming season. But don’t worry! Articles will continue to be published every day to keep you entertained, informed and dreaming of spring.

This year marks the 10th anniversary of the Laidback Gardener blog, and for the occasion we’ve compiled a list of the 30 most popular articles of all time. Some must-reads are a natural on the list, while others may surprise you. These choices reveal what has piqued our curiosity and fuelled our passions over the years.

Among these memorable articles, this one by Larry Hodgson on growing vegetables indoors in winter ranks 29th on our list. This fascinating topic answers a question many gardeners have: can you really grow vegetables indoors, even during the cold season? Originally published on November 5, 2015, this text explores the challenges, techniques and tips needed to make this practice a success.

Can we grow vegetables indoors in winter? Not just seedlings that we’ll later transplant into the ground, but vegetables that will ripen in our homes during the cold season? Tomatoes, peppers, lettuces, etc., just like in an outdoor vegetable garden?

My answer is: yes… but not easily.

Lack of Light

The limiting factor in our homes is light. Providing the right temperature is easy (vegetables like about the same temperature as humans). Watering is easy to organize, ambient humidity can be raised to 50-60% without too much difficulty using a humidifier, and there’s a vast choice of potting soils, fertilizers, pots and so on. But where to get the bright light that vegetables love? In summer, in front of a large, south-facing window, you can, but in autumn and winter, with short, grey days and very weak sunlight… not so much.

But let’s not lose hope: there are still possibilities.

Here they are, in order of simplicity.

1. Sprouts

It’s very easy to germinate the seeds of many vegetables and grains indoors. In fact, all you need is a Mason jar and a piece of mosquito netting. And you’ll have “vegetables” to eat very quickly, in about a week, without any light if you prefer, or with only normal indoor lighting.

Why are sprouts so easy? Because you’re going to harvest the plants very young, when they’re still germinating, before the lack of light harms them.

2. Shoots and Microgreens

It’s almost the same as sprouts, but you sow the seeds in potting soil this time… and harvest them a few days later than the sprouts, in about 2 weeks’ time, when the cotyledons (the first leaves) are fully developed. And here, more intense lighting is needed: a sunny windowsill or a spot under a fluorescent or LED lamp, for example.

Microgreens are distinguishable from shoots by their more advanced stage of development. They are harvested when the cotyledons are fully developed, sometimes accompanied by the first true leaves. Micro-shoots require a potting soil or other substrate for their growth, as well as direct or artificial light to encourage their development. Only the aerial parts (stems and leaves) are consumed

Eating raw roots from potting soil can present risks of contamination. In commercial sprout production, inert substrates (such as coconut fibre or growing mats) are often used to minimize these risks. I recommend eating only the aerial part.

Here are a few vegetables that are easy to grow as sprouts or shoots:

1. alfalfa
2. amaranth
3. arugula
4. basil
5. beet
6. broccoli
7. cabbage
8. carrot
9. chervil
10. chickpea
11. clover
12. corn
13. corn
14. fennel
15. lentil
16. lettuce
17. mung bean
18. mustard
19. oats
20. onion
21. parsley
22. pea
23. radish
24. rice
25. rye
26. sesame
27. soy bean
28. spinach
29. sunflower

There’s a more in-depth article on growing sprouts here.

3. Leafy Greens Under Artificial Lighting

Leafy vegetables require less light than fruiting vegetables, and ripen faster too. It’s therefore possible to grow them without too much trouble… but not in front of a window in autumn or winter: there’s not enough light. On the other hand, with an LED or 2-tube fluorescent lamp suspended over a table or shelf, you can grow your lettuces anywhere: in the basement, attic, under a staircase, in a closet, etc.

Your lamps will probably only be used for 6 months a year, and can then last 6, 7 or even 8 years. Change tubes when they start to blacken at the end. LED lamps last even longer.

Add an inexpensive timer to this system. A 14-hour day will suffice.

How to Grow Leafy Vegetables Indoors

The technique is very easy. Fill pots or trays with moist potting soil (I like potting soils that already contain mycorrhizae) and sow the seeds about 1-2 cm (1/2″) apart, barely covering them with potting soil. Adjust the height of the lamp so that it is about 15 cm (6″) from the pots. As the plants grow (and they will grow very fast!), raise the lamp so that it is always about 15 cm (6″) from the top of the plants.

Water as needed when the soil is dry to the touch, adding a little seaweed fertilizer to the water.

How you look after your plants afterwards is up to you.

Some gardeners like well-formed vegetables, with a nice individual rosette. If so, transplant the plants into individual 10-15 cm pots when they start to settle. Most lettuces will form a nice rosette ready to harvest in 40 to 60 days.

I prefer to harvest my lettuces young, without transplanting them, when they are 15 cm tall, i.e. in about 20 to 30 days. I cut them about close the ground… and let them grow back. Normally, I get a second harvest and sometimes even a third.

Sow them successively from autumn onwards, and you’ll have fresh lettuces to harvest right through to spring.

Which vegetables to use? I suggest mesclun (a mixture of leafy vegetables): it will give you a bouquet of flavors in a small space. Or sow “greens” individually: lettuce (leaf lettuce is the quickest), spinach, arugula, beet (for its leaves), lamb’s lettuce and so on. You can also grow certain herbs this way: basil, coriander, parsley, etc.

As for root vegetables, the easiest is the small round radish, which is easy to grow using the method explained. For the others, I suggest more or less the same technique, but use deeper pots, space the plants further apart… and limit yourself to small-format root vegetables: baby carrots, baby beets and so on. It’s hard to get big, long roots in a pot.

4. Fruiting Vegetables Under Artificial Lighting

I remain unconvinced of the advantages of growing fruiting vegetables indoors in winter. I’m not talking about sowing them indoors in spring with a view to transplanting them in the summer garden (that’s easy), but about trying to grow tomatoes, cucumbers, eggplants, etc., indoors in autumn with a view to a winter harvest.

Costs start to rise quite a bit when you try to grow such large, sun-hungry plants in the house. And they take months to mature, rather than weeks like leafy greens. The further away the harvest, the more time there is for mistakes. But if you insist…

One low-cost option is to try to combine natural sunlight with artificial lighting. For example, you could hang LED or fluorescent lamps (preferably with 4 tubes for greater intensity) over seedling pots placed in front of a window, raising the lamp as the plants grow (keep them 15 cm, 6″, from the top of the plants).

I suggest using small vegetables (tomatoes and cucumbers designed for pot cultivation, dwarf beans, etc.), as it’s difficult to light tall plants adequately under a fluorescent or LED lamp: you have to constantly raise the lamp, and so the lower leaves, too far from the light source, no longer get their share of illumination. It is, however, possible to position the lamps laterally or to use several LED lamps around the plant.

5. Fruiting Vegetables in a Grow Room

Or convert a room in your home into a grow room.

To grow vegetables indoors optimally, it’s possible to adopt controlled cultivation techniques similar to those used in grow rooms. This involves the use of powerful LED grow lights that offer a spectrum of light suited to plant growth.

In some cases, you may add additional equipment, such as a dedicated electrical outlet, a temperature and humidity control system or, for the most demanding crops, a CO2 generator. These installations can involve high initial costs depending on the equipment chosen. In addition, monthly electricity bills can rise, especially if lighting and ventilation are running continuously.

You can grow vegetables in pots with potting soil or opt for hydroponic systems, depending on your preferences and level of expertise. However, it’s important to note that, although this method offers a year-round harvest, the cost of production can exceed that of supermarket-bought vegetables. To make the most of your investment, it’s advisable to focus on vegetables with high added value or those that are hard to find in stores, such as fresh herbs or certain exotic vegetables.

Yes or No?

Vegetables in the house, even in winter? Yes, it’s possible, but let’s face it: it’s not as “natural” as growing them in the ground in summer!