Topic: Tomatoes not ripening

[Garden Manager]

I have a problem, not with the plants priducing fruit but with the ripening of them. My plants both in the greenhouse and outdoors are producing loads of fruit (had to 'shore up' some of the trusses because of the weight), but they remain stubbornly green and not a sign of red anywhere.

I have even resorted to placing ripe fruit (a banana) in the greenhouse in the hope this will encourage the 'tommies' to 'turn'.

Has anyone had this problem and/or can offer any advice please?

[Svea]

everyone seems very impatient with their tomatoes. should they be ripe already? i am very happy to wait another month if need be.......doing them for the first time i didnt expect to eat tomatoes until the second half of august, at the earliest

svea

[aquilegia]

Patience my dear!

I have several green ones, but don't expect them to rippen just yet. It's not that warm and sunny (again) for one thing!

[Garden Manager]

Hmm, I was half expecting to be told 'patience'. Thing is some of the fruit has been 'ready' to ripen (or so i thought) for ages, even before the last hot spell.

I always thought that the greenhouse ones came a lot earlier than the outdoor ones, but at the moment the outdoor ones are fast catching the greenhouse ones up!

Perhaps i am being impatient. its just i have been eating homegrown salad with shop bought tomatoes for what seems like ages, longing to be able to eat my own. Shop ones are just not the same.

Thanks anyway.

[Mrs Ava]

My outdoor ones are ripening good and fast, my greenhouse ones are a lot slower.  I seem to remember last year being told, maybe my John Miller, that too much heat slows the ripening process down!  If I can beat the blight, I think I will save my greenhouse next year for melons and grow all my toms on the allotment!

[dicky]

Hi

I've got the first signs of some ripenig but I think it's a bit early for the main crop, just not enough sun yet, usually goes mad once it starts

[ruud]

I got the same problem e.j,the ones outdoor are much quicker,than the one in the greenhouse.

[Roy Bham UK]

::) Snap Rudd and EJ same here but being a newbie I don't understand why? What is the point in buying grow bags for greenhouse toms if mother earth tends to them better?
The mind boggles ::)

[john_miller]

Most varieties of tomatoes have a gene that initiates ripening from the inside out ( cv. Buffalo, most notably, doesn't have it) so even though nothing appears to be happening the fruit is ripening.
At first, when they are swelling, tomatoes are a relatively dark green colour. Once they have reached full size and ripening is progressing there is a very visible change in the shade of green to a much lighter tone. Once this happens it is only a short period of time before the blossom end, which is where 'pinking' is first visible, will then change colour indicating the fruit is finishing ripening.

::) Snap Rudd and EJ same here but being a newbie I don't understand why? What is the point in buying grow bags for greenhouse toms if mother earth tends to them better?
The mind boggles ::)

The problem isn't mother earth Roy it's the average British summer! Gro-bags in themselves won't make a huge difference but if it allows indoor cultivation then they are worth it. Last summer being a case in point?

[Kepouros]

An overheated green house will not actually delay the ripening of tomatoes but can certainly affect the colour, and during the last few weeks many small greenhouses have severely overheated.
The colouring of ripening tomatoes depends on the ratio of two chemicals, lycopene and carotene.  Lycopene, which provides the red colouring, is not generally produced (in this country at least) in temperatures above 80 deg F.  Fruit exposed to the sun may well exceed this temperature for most of the day; Carotene will still be produced and will result in a yellowish tinge but the Lycopene will only be produced when the temperature drops at night, and if this cycle continues for any length of time the fruit will never attain the full red colouring but will turn to an indeterminate orange and may be patchy.  In heatwave conditions the colouring of outdoor tomatoes may well be better than that of greenhouse ones as a result.

The simplest and most effective way of cooling a greenhouse is, of course to pour water onto the path or spray into the air, either of which will also considerably help in the setting of the fruit.

[jennym]

I was taught that:
Lycopene is a carotenoid.
Tomatoes take about 50 days from fertilisation of the flower to full ripening. Optimum ripening temperatures are 18 - 21 degrees C.
Ethylene is the causative agent of the ripening process.
Ethylene is produced naturally, but can be introduced artificially, or stimulated by stressing the plant.
Hope this helps.

[john_miller]

Ethylene by itself is not the causative agent of ripening. There are many other processes involved that are genetically controlled such as the conversion of starches to sugars and the production of lycopene and carotene by phytochrome genes. Ethylene is a by-product of ripening but can be also used to induce some ripening-like chemical changes in fruit. This is widely done over here for some fruits, notably tomatoes and bananas, that have to be shipped over large distances. It is also commonly used in Europe on late tomatoes to turn the fruit red just prior to the plants being removed (it kills the plant too). This facility is also used commercially to induce flowering in Bromeliads as the plant is induced into early senescence and flowers as a result. To ensure an extended shelf life and reduce transportation damage tomatoes and bananas are commonly picked before they are ripe (and still firm) and then gassed with ethylene after transportation to induce these changes. However, the resulting product is not 'ripe' as many of these other chemical changes have not taken place.

[jennym]

John, but doesn't ethylene regulate some of the ripening processes? I was taught that auxin and other hormones involved in growth help to generate it in various plant tissues, which have receptors which then respond to ethylene in different ways, one of which is ripening. The ethylene also helps to degrade chlorophyll, hence its use for citrus fruits.
But I'm a rookie when it comes to botany - discuss!

[tim]

Clever stuff apart - most interesting - I could not plant my toms outside in the first week of April knowing that we get sharp frosts until at least mid May

[Garden Manager]

Cor! some interesting stuff there and no mistake. Thanks.

The heat thing does ring some bells. My greenhouse overheated regularly during this summers heatwaves, despite vents and damping down. Perhaps this has slowed things down.

Encouragingly some are geting paler, so some are at least on the way towards ripening.

How I wish i had paid more atention when we covered plant hormones in the RHS advanced course i did. I remember the bit about ethylene (and growth hormones - not much help here), hence why I put the banana in with the greenhouse tomato plants. I can't remember much else about flowering and fruiting unfortunately.

So 18 - 21 c if the optimum ripening range then? At that rate the greenhouse toms will 'turn' first. During this recent weather outside temps have been below 18 at times duing the day, but the greenhouse has been OK. So there is hope!

I am now concerned that the outside toms will be blighted  before they ripen. This wet weather is perfect for blight to get going. I have sprayed with Bordeaux mixture as a preventative, but I fear the rains will wash it off before it can do any good. :(

[tim]

Bordeaux - just keep spraying after the rain.

"Before it can do good"? Remember it's only a barrier?

Temperatures? Until the hot spell, ours were often as low as 10C - then 85C+in the heat.

[Garden Manager]

Bordeaux - just keep spraying after the rain.

"Before it can do good"? Remember it's only a barrier?

Temperatures? Until the hot spell, ours were often as low as 10C - then 85C+in the heat.

Surely Tim if the Bordeaux acts as a barrier then that barrier is doing some 'good'. therefore if it gets washed off then it wont 'do any good'  Yes?

Hmm when the rain stops I'll try again with a spray perhaps.

[Vony]

This year so far my green house has been a bit of a disaster

[Mrs Ava]

What Tim means is Bordeaux isn't a cure, if you have blight, treating with bordeaux isn't going to make the plant well again, it will still die.  So, once the plants are dry again, you do have to spray again. 

Why has your greenhouse been a disaster Vony??

[tim]

Yes, Richard!

Thanks, Emma - not what you might call an active do-gooder.