Windowsill bean problems.

[leke]

I have been growing some [url=https://en.wikipedia.org/wiki/Phaseolus_coccineus]scarlet runner beans[/url] on my windowsill since April 1st. Their leaves have changed colour recently and I'm wondering if it's a problem.
Here's a pic of two of the leaves: https://I.imgur.com/o2bYN.jpg
This is fairly new growth. I guess the leaves shouldn't be like that though. Any idea how I could remedy this?

Thanks.

[applestar]

Scarlet runner beans would need a big container and full sun (at leat 6 hours direct sunlight). How big are the vines? How big is the container? Are they starting to climb up their support?

If in container that is too small, then the roots may have filled the container and are circling around, strangling itself. It may also have exhausted the nutrients in the soil.

Also, it can sometimes get very cold by the glass. Has there been significantly colder weather?

[leke]

Scarlet runner beans would need a big container and full sun (at leat 6 hours direct sunlight). How big are the vines? How big is the container? Are they starting to climb up their support?

If in container that is too small, then the roots may have filled the container and are circling around, strangling itself. It may also have exhausted the nutrients in the soil.

Also, it can sometimes get very cold by the glass. Has there been significantly colder weather?

Thanks for the suggestions.

The window, this time of year, gets plenty of sun and the window is well glazed so there is no draft -- although a side window is sometimes opened which could send some cold air to the plants. It's been between 0C -- 5C / 32F -- 41F outside.

The plants grew to the height of the windows (about 1.5 meters) and I recently clipped their growth.

I haven't transplanted the plants yet to larger containers. They are still in fairly small pots 250ml and 500ml. I guess that's the first thing I should do.

The plants are just over a month old. Would you recommend I start introducing nutrients to the water yet?