I have loads of green tomatoes in greenhouse with no sign of turn red, when should I expect them to start turn red and is there anting I can do to speed them up. I've also heard about banana peels, people say that if you hang the banana peel on a branch near the tomatoes, it will turn red faster, is that true?

Thank you!

Welcome to the Junction from Down Under @drewdavis .

Whereabouts are you located, an introduction thread telling us a little bit about yourself and where you are located would help people offer advice.

Are you at the start of your season or near the end? If the former, the fruit may not be anywhere near ripe, what varieties are you growing, are your fruit full size, how much light are they getting, it maybe that they will ripen naturally within a couple of days and to push them can lead to mealy, low quality fruit.

While I don't particularly recommend trying to speed it up, there are a number of things that can potentially speed up the ripening:
- Phosphorus (if your soil is deficient, or if phosphorus isn't available enough your tomatoes might not ripen as quickly)
- Damaged tomatoes seem to ripen faster (especially around the area where they were damaged)
- Tomatoes with BER ripen faster (I think for the same reason damaged tomatoes do).
- I imagine ethylene from banana peels or whatever might help. It makes sense, but I don't know if it helps at your particular stage of greenness, whatever that is.
- Potassium; it does seem to help reduce the DTM, in my observations from adding potassium earlier in the season, but I don't know if it'll help at this stage of maturity. It might not help in all gardens, either. It could depend on what's going on in your soil.
- Harvesting the green fruit and bringing it inside to ripen. I could be wrong, but that seems to speed it up sometimes, but it tastes better ripened in the sun (whether it's on or off the vine; ideally on the vine), I think. Actually, if you have shaded tomatoes that need more sun to taste better, you could probably harvest them, put them by a sunny window, and they might end up tasting better after a day or two.

Assuming your tomatoes are green-ripe and fully mature, there are a couple of things that can delay ripening.
1) Temperature too hot/ temperature too cold. Heat can delay ripening as much as cold can, so consider your data for daytime and night time temperatures. Tomato enzymes for ripening have a narrow temperature window in which they function optimally, or at all.
2) Fruit load. Especially for determinates, but can affect indeterminates as well: If the plant has a big load of fruit on, and is not done growing the fruit with the available resources (fertilizers), it can delay ripening of any of the fruit. Plants that were generously fertilized may take longer to ripen the crop, but it will be a bigger crop.
3) Air flow can delay ripening. If a strong breeze is constantly stripping away the ethylene that is being given off by the ripening or near ripe fruit, it will slow them down from ripening, especially if the air is cooling them a bit below optimal at night.

If you could give us a better description of your greenhouse situation, temperatures day and night, type of plants (determinate or indeterminate), running fans? or other ventilation, we could better advise you.

I would not advise hanging banana peels around your fruit hoping to ripen them. The ethylene they give off naturally is just one of the processes related to ripening - if they aren't giving off the ethylene, those other processes, such as lycopene (red color) production, aren't happening either and there's a reason for that. Ethylene won't solve the problem if it's just too hot (or too cold) for that process to work. If it's cool or breezy at night, I would recommend to cover the plants with row cover at night and let the ethylene build up that way around the fruit. This worked for me in a semi-sheltered cool windy autumn situation, and really speeded up ripening.
I didn't figure out a fix for ripening delayed by being too hot. Hopefully someone else may have. As a last resort if you must have some ripe tomatoes immediately, I would suggest to pick some that you know are fully mature green ripe, and put them in a closed box in conditions ideal for ripening: temperature 65-70F. They should color up in a few days. If they don't, you are misjudging how ripe they are and should leave them on the vine and wait.

Welcome to the forum!

I don't see any mention of the variety that is not ripening - is this about the time the variety or varieties are expected to turn ripe? I've had some later season types (not determinate), that would get a bunch of green tomatoes on them, and they would sit full sized, before ripening, while other earlier season types would start producing tomatoes later, but ripen earlier, as expected. Go figure - that's why I don't grow too many later season varieties.

drewdavis wrote: ↑Tue Apr 02, 2024 3:13 am I have loads of green tomatoes in greenhouse with no sign of turn red, when should I expect them to start turn red and is there anting I can do to speed them up. I've also heard about banana peels, people say that if you hang the banana peel on a branch near the tomatoes, it will turn red faster, is that true?

Thank you!

That happens to me ALLLLLLL the time on large varieties. Best thing to do is just wait them out. Eventually they will turn red; but patience is a key! Good luck and welcome to the forum!

Temperature.

Tomatoes ripen faster between 22 to 25C.

A local greenhouse grower picks his tomatoes green and gasses them with ethylene. People buy them, but I don't think they taste very good.