I'm trying to extend my growing season since the weather's getting cooler here. I have a sunny window but it doesn't get direct sun for more than a few hours. Should I use grow lights, or can I manage with just the window light? Also curious what varieties actually do well indoors during winter months.
Don't rely on a few hours of window light alone - lettuce and greens need consistent brightness to stay tender and not bolt, and fall/winter light is already pretty weak. Grow lights will make a huge difference; I set up a simple LED panel over my winter greens last year and watched them actually thrive instead of getting all leggy and bitter. Stick with fast-growing, cold-tolerant varieties like arugula, spinach, mâche, and buttercrunch lettuce - they handle indoor conditions better than the big romaine types. You'll want to keep temps around 60-65°F if you can, and give them 12-14 hours of light daily; even modest LED strips work fine and don't cost much.
You'll probably want to add grow lights if you're serious about winter greens, since a few hours of window light isn't really enough for most lettuce to thrive. Leafy greens like spinach, arugula, and the looser leaf lettuce varieties (like buttercrunch) do way better indoors than heading types, and they grow faster too. If you're set up with decent light and keep temps around 60-65°F, you can get a decent harvest in maybe 4-6 weeks. The main thing is making sure you're not overwatering in low light conditions - that's how most people's indoor winter greens get leggy or moldy.
How much are you willing to spend upfront - is this a casual experiment or are you going all-in? Because here's the thing: those earlier answers aren't wrong about needing lights, but they're being a bit pessimistic about window-only growing. I've kept lettuce alive on a north-facing windowsill through winter before, and it works fine if you pick the right stuff - mesclun mixes, spinach, and Asian greens like mizuna actually tolerate lower light better than butter lettuce or romaine. They just grow slower and stay smaller, which honestly is perfect for continuous harvesting anyway.
That said, if you want decent-sized heads and faster turnover, even cheap LED shop lights mounted above a small shelf will transform your results. The combo that works best for most people: use your sunny window as your base, supplement with a light on a timer for maybe 12-14 hours a day, and you're golden. Varieties-wise, stick with the leafy, cut-as-you-go types rather than heading varieties - they're way more forgiving indoors and keep producing through winter without needing perfect conditions.
Window light alone is actually workable if you're strategic about it - the real trick is choosing cold-season varieties that don't mind lower light, like mâche, winter purslane, or the tougher Asian greens like mizuna and tatsoi, which genuinely prefer cooler temps and won't get leggy as fast as butter lettuce would. If you want to avoid buying grow lights, try positioning a reflective surface (even just white poster board) behind your plants to bounce whatever light you do get, and rotate your containers daily so no side stays shaded. That said, if you can grab cheap LED shop lights from a hardware store and hang them a few inches above, you'll get way more consistent results and a faster turnover - it's less about spending big money and more about having plants that actually produce rather than just survive.
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