How to Grow Vegetables Indoors in Winter: Lights, Crops & Care

You can grow a steady supply of fresh greens, herbs, and microgreens indoors through the darkest months, and the single thing that makes or breaks the effort is light. Outdoors in December most of the US gets under 10 hours of weak, low-angle sun; a windowsill delivers a fraction of what a tomato or pepper needs, but it is plenty for leafy crops if you add a modest grow light. Get the light right, keep the room between 60 and 70°F, choose fast leafy crops instead of fruiting ones, and you will be cutting salad in January from a shelf in your kitchen. This guide walks through grow lights, the best winter crops, temperature, containers, and exactly how many hours to run your lights.

Why winter windowsills are not enough

Plants run on light, and the problem with winter is not just the cold — it is the lack of usable sunlight. From November through February, the sun sits low in the sky, days are short, and clouds are common across most of the country. Even a bright south-facing window delivers far less light than an outdoor garden in summer, and that light only reaches a narrow band right at the glass. A few feet back into the room, intensity drops off a cliff. Light falls off with the square of distance, so a plant two feet from the window receives roughly a quarter of the light it would get pressed against the glass.

This is why people who try to overwinter a tomato or grow basil on a January windowsill end up with pale, stretched, leggy plants that lean hard toward the glass. The plant is reaching for light that is not there. Leafy greens and herbs are far more forgiving than fruiting crops because they only need to make leaves, not flowers and fruit — but even they will sulk on a bare windowsill in deep winter. The fix is simple and cheap: a supplemental grow light. With one, your kitchen counter becomes more reliable than the sunniest window in the house.

Choosing and positioning a grow light

For a home setup, modern full-spectrum LED grow lights are the easy answer. They run cool, sip electricity, last for years, and put out the warm-plus-blue spectrum leafy crops want. You do not need an expensive horticultural fixture to grow salad. A simple LED bar or panel rated for plant growth, or even a pair of daylight (5000–6500K) LED shop lights, will keep greens and herbs thriving. Avoid old-style incandescent “grow bulbs,” which waste most of their energy as heat and barely help.

How far above the plants?

Distance is the lever most beginners get wrong. For LED grow lights over leafy greens and herbs, start with the fixture 6 to 12 inches above the top of the plants and adjust from there. Too far away and plants stretch toward the light, growing tall and floppy with wide gaps between leaves. Too close and tender seedlings can scorch or bleach. Watch the plants: compact, deep-green, sturdy growth means the height is right. Leggy, pale, leaning growth means the light is too weak or too high — lower it or add a second fixture.

Coverage and reflectivity

One light bar covers a limited footprint, usually a single shelf or seed tray. If you are filling a wider shelf, use multiple bars side by side so coverage is even — plants at the dim edges will lean and underperform. Surrounding the growing area with white walls, white poster board, or reflective material bounces stray light back onto the plants and noticeably improves growth in a corner setup. A cheap timer is non-negotiable: it keeps the photoperiod consistent so you are not relying on memory to switch lights on and off every day.

How many hours of light per day

Indoor crops need a daily rhythm of light and dark, just like outdoors. Plants use darkness for important metabolic processes, so do not run lights 24 hours a day — you will not get faster growth, and some crops resent it. Set a timer and use these targets as a starting point:

• Leafy greens (lettuce, spinach, kale, chard, arugula): 12–14 hours per day.
• Herbs (basil, parsley, cilantro, mint): 12–16 hours; basil in particular loves the higher end.
• Microgreens: 12–16 hours once they are up and green, but they need little to no light during the first few days of germination.
• Fruiting crops (dwarf tomatoes, peppers, if you attempt them): 14–16 hours of strong light, and even then results are modest indoors.

If your plants are stretching despite a full photoperiod, the issue is usually intensity (light too weak or too high), not duration — adding more hours rarely fixes a leggy plant. Lower the fixture or add another light before you extend the timer past 16 hours.

The best crops to grow indoors in winter

The golden rule of winter indoor growing: grow the parts of the plant you can harvest quickly. Leaves and shoots mature fast and tolerate lower light; fruits demand far more energy and patience. Here is where to focus.

Salad and cooking greens

Loose-leaf lettuce is the champion of the indoor winter garden. It germinates in days, tolerates cooler rooms, and lets you cut outer leaves repeatedly for weeks as a cut-and-come-again crop. Spinach, baby kale, Swiss chard, arugula, and Asian greens like pak choi and mizuna all behave the same way: sow thickly, thin as needed, and harvest young. These crops actually prefer the cooler 60–65°F end of room temperature, which suits a winter house perfectly. Sow a fresh tray every two to three weeks for a continuous supply rather than one big planting that all matures at once.

Herbs

Fresh herbs are one of the most rewarding indoor winter crops because store-bought herbs are expensive and fade fast. Basil, parsley, cilantro, chives, mint, and oregano all grow well under lights. Basil is the most light-hungry and wants warmth (65–70°F) plus 14–16 hours of light; parsley, cilantro, and chives are more forgiving and handle cooler corners. Pinch herbs regularly to keep them bushy and prevent them from bolting (flowering), which turns the leaves bitter. If you are tight on space or light, a windowsill herb pot is a great companion to a larger leafy-greens shelf — see our guide on small-space and container growing for ways to fit more into a kitchen corner.

Microgreens: the fastest indoor crop

If you want a harvest in seven to fourteen days with almost no equipment, grow microgreens. These are simply the seedlings of vegetables and herbs — radish, broccoli, pea shoots, sunflower, mustard, kale — harvested at the first-true-leaf stage. Because you eat them so young, they need surprisingly little light and no fertilizer; the seed itself fuels most of the growth. Sow seed densely across the surface of a shallow tray of moist mix, keep them covered and dark until they germinate, then move them under light for a few days to green up before cutting with scissors. They are nutrient-dense, fast, and almost foolproof, which makes them the perfect entry point for a first-time indoor grower. Microgreens are also the crop most worth scaling up if you enjoy the process.

What to skip (mostly)

Tomatoes, peppers, eggplants, squash, and other fruiting crops are poor candidates for casual indoor winter growing. They need intense light for months, hand-pollination indoors, and a lot of space, and the payoff is usually a handful of small fruits. If you are determined, dwarf or “patio” tomato varieties under a strong dedicated light can work, but treat it as a project rather than a food source. For winter calories and steady harvests, leafy greens, herbs, and microgreens win every time.

Temperature, humidity, and air

The good news is that a comfortable home is comfortable for most indoor crops. Aim to keep your growing area between 60 and 70°F. Leafy greens lean cooler and happily take the low 60s; herbs like basil prefer the upper end. The temperature mistakes that hurt indoor plants are the extremes: a cold draft from a single-pane window on a freezing night, or the hot, drying blast of a forced-air heating vent. Keep trays a few inches off icy glass, and never set plants directly above or in front of a heat register, which will scorch leaves and dry the mix out in hours.

Winter heating makes indoor air very dry, and that is the second hidden challenge. Low humidity stresses seedlings and herbs and invites problems. Grouping plants together raises local humidity, a tray of water nearby helps, and a small humidifier solves it entirely if your home runs especially dry. At the same time, a little air movement matters: stagnant, humid air around densely sown trays encourages damping-off and mold. A small fan on low, running gently nearby, strengthens stems and keeps fungal trouble away. You want air that moves, not a gale.

Containers, soil, and watering

Almost any container works as long as it has drainage holes and a saucer to catch runoff. Shallow seed trays and 1020 flats are ideal for greens and microgreens; 4- to 6-inch pots suit individual herbs. The depth you need depends on the crop: microgreens and baby greens are happy in just an inch or two of mix, while herbs and full-size lettuce want 4 to 6 inches for their roots.

Do not bring garden soil indoors. It compacts, drains poorly in pots, and can carry pests and fungus gnats into your home. Use a light, sterile potting or seed-starting mix — typically peat or coco coir based with perlite for drainage. If you are weighing the two base materials, our comparison of peat versus coco coir as a growing medium explains how each behaves in containers. Water when the top of the mix feels dry to the touch: enough that a little drains from the bottom, then empty the saucer so roots never sit in standing water. Overwatering, not underwatering, kills most indoor plants and breeds fungus gnats. Because potting mixes hold little nutrition, feed leafy greens and herbs every couple of weeks with a diluted liquid fertilizer once they have a few true leaves — microgreens need none.

A simple plan to start this week

Set up one shelf or a clear stretch of counter near an outlet. Hang an LED grow bar on a timer 6–12 inches above where the plants will sit and set it for 14 hours a day. Fill a couple of trays with moist seed-starting mix: one of loose-leaf lettuce and baby greens, one of radish or pea microgreens, and a small pot of basil or parsley. Keep the room around 65°F, run a small fan on low nearby, water when the surface dries, and start a fresh tray every two weeks. Within a week or two you will be cutting microgreens, and within a month you will have salad greens and herbs — all from inside, while it snows outside.