I'm a newbie in the gardening world and have been doing some research on indoor gardening during winter months. I currently have a tomato, bell pepper and a few hot pepper varieties growing outside in containers. My research has taught me that the peppers can be overwintered and tomatoes can often keep producing inside for several weeks with the right conditions but is it possible to bring these inside and keep them producing the entire winter (with appropriate light and heat of course), then move them back outside come spring again and have fruit continuously growing? I've googled but seem to get conflicting answers. Does anyone have actual experience with this?
I once volunteered at a greenhouse that tried to provide fresh tomatoes to local restaurants throughout the winter. We were able to keep the tomatoes growing, but they stopped producing after a few months because we couldn't afford to heat the all-glass greenhouse at a suitably warm (75 F) temperature. Because the house got to below 50 F at night, the fruits weren't all that great anyway (temps below 50 F "turn off" a key "flavor gene" in the fruits). The real problem here was lack of heat, although the greenhouse really didn't get enough hours of light during our cold northern US winters anyway. As you might expect by my comments, the experience was a failure. BTW, we grew the plants in potting soil in 7 or 10 gallon pots—I don't remember which.
Now, given this experience, I think you would have much better luck than the non-profit did if you:
- Use tomatoes that are indeterminate (this is a must!)
- Provide at least 12 hours of complete-spectrum light, possibly skewed towards the "fruiting" spectrum. I would almost certainly use LEDs if I were in your situation, although they are pricey (at least here in the States).
- Provide a room or small greenhouse that maintains temps of at least 75 F during the day, and 65 F at night. If outdoors, this would be very expensive, although you could rig up a small greenhouse in a basement. If you do this, you MUST vent it and make sure that the lights don't overheat it. Be VERY AWARE of possible fire hazards from the lights or any other equipment.
- Possibly not use the potting soil/large pot setup that we used and switch to hydroponics, but that, too, entails additional expense.
- Prune the tomatoes to induce new growth and to try to keep their sizes manageable.
Given the relatively large outlay of cash required, you may be better off frequenting any winter markets that may exist in your area. I'm fortunate enough to live in an area where we have enough small growers and farmers who raise tomatoes, peppers, and (primarily) leaf crops that are sold at a central market for most of the winter. These tend to be raised organically, but that may not always apply because of the many pests and diseases that can arise in greenhouse/indoor culture.
One last experience from my time at the greenhouse - when the winter was ending, the greenhouse manager took cuttings from the tomatoes, which he rooted in small pots. He timed this so when the temps had moderated (late April in my area), the cuttings were ready for repotting. We tossed all the old plants at that time and put the cuttings in new potting soil in the sterilized old pots. If you do try to over-winter producing tomatoes, you could try this method rather than trying to move the (by then, very large) plants back outdoors.
You have not mentioned where you are, but it is certainly possible to grow Nightshades (tomatos and peppers are in this family) in Winter and get fruit, provided there us adequate heating and sunlight. The yields will drop off considerably though.
The rule of thumb I was taught us 1% more light = 1 % more growth, so shorter winter hours and lower solar intensity can massively impact yields (and our eyes play tricks on us with respect of judging the amount of light because our pupils dilate - you should use a meter - even if its on your cellphone).
You also need to keep plants warm. In commercial hothouse operations this is a huge cost, which is why fruit is more expensive in winter.
The nightshades you mention are typically good for only 1-3 years, and you would need a systrm to manage their continued growth. (Hothouses grow them on strings they wind around the plant and lift up as the plants grow.
@Jurp answer is spot on, save for requiring heirlooms.
You might not like this, but the more traditional/practical way to get fruit in the winter from many plants is to can, dehydrate, freeze, pickle, or lacto-ferment the vegetables. If you're not traditional or practical, that's awesome.
Some vegetables will store through the winter: e.g. Red-seeded Citron watermelons (I had one store 18 months), winter watermelons, winter muskmelons, winter squash, some kinds of tomatoes (especially longkeeping tomatoes; they should just call them winter tomatoes, IMO), potatoes, some onions/shallots/garlic, etc. If you have fruit in the winter, the need to have plants living and producing during the winter is lessened.
If you want plants to live indefinitely, you'll want perennials or tender perennials. Annuals die after a season or so (cold or no cold). Tender perennials die if it's cold (but in a warm climate could live much longer). Regular perennials can take a freeze and live for years.
Some crops, if you harvest them, the whole plant is gone (e.g. radishes). You can replant parts of some plants to grow them again (e.g. celery, lettuce, etc.); I'm not sure how practical that is to do repeatedly, as I haven't tried it.
You might succeed in getting some kinds of tender perennials to live up to a few years, but it's generally easier to plant new ones (seed-saving is pretty fun). Trying to get vegetables year-round is something a lot of new gardeners want to do (and probably attempt to do). If you're serious about it, you could probably figure out a way to do it (however expensive it is, and however high the learning curve is), but it's not for the faint of heart.
There are full-on perennial vegetables: horseradish, sunroots, and bunching onions are some good ones; chicory is nice (but it doesn't live forever); don't forget rhubarb, fruit trees/bushes (fruits are vegetables by at least one definition), etc. You can harvest sunroots all winter (as long as the ground isn't too frozen); you don't really harvest them during the summer, but you can do it in the spring.
You could grow a makrut lime tree indoors (and use its leaves as a seasoning in cooking all-year long); that would be practical and inexpensive, as long as you have a window with an appreciable amount of sun. Citrus trees can live for decades indoors, at least. I have a grapefruit tree approaching 30.
You could grow Sempervivum all-year round (you can eat some kinds, and use it like Aloe vera). I mean, the plants still have leaves during the winter, even outside. In theory, you could eat them continually. They taste kind of lemony, kind of like sour apples, and kind of astringent. I would think they'd make decent houseplants in a window plant trough, but I haven't tried it.
You can grow sprouts and microgreens all year-long, but of course, the individual plants don't live indefinitely.
There are some reasons a lot of gardeners don't want to try growing stuff indoors indefinitely:
- Humidity (plants can make a house more humid, which may invite mold onto your walls)
- Learning curve
- A break from gardening in the winter is really nice.
Many plants tend to have a lifespan. So, just because they're perennials that doesn't mean they'll necessarily live forever, even if you take perfect care of them. Many perennials normally only live a few years.
I probably don't have as much experience as you're looking for with this sort of thing, but this probably wouldn't make a good comment (as opposed to an answer).