There is still plenty of room for them to grow.
I live in the Netherlands, the temparature ranges from 10-30 degrees Celcius the last 2 months I put it outside.
It has sunny like 2 days out of 7.

The thing is, 3 other containers that I put outside at the same time are doing pretty fine. They were bigger stems though.

Soil looks very peaty. Insert your fingers beneath the surface to about an inch or so. Does it feel moist or dry. Peaty soils become hydrophobic in outdoor sun (very resistant to water).

It stays wet for around a half day. Is this enough, too much or too dry?

I was thinking that the soil looked like garden earth, not a potting mix.

@rhizo it is potting soil from the garden shop though :p

I have lemon grass growing outside my door and there are a lot of brown dead leaves that I will eventually pluck to make room for the new leaves that will grow. This is my first lemongrass but I have noticed that it grows cyclically. At some point I think you will see some new growth in the middle of the plant.

@jerzeegirl i hope it will grow again :D Thanks for your input

Thanks. Not superb growing conditions for lemongrass, but still workable. Your days are shortening now so dieback is expected - this is the time when mature stalks would develop seeds and the leaves would brown off anyway. The dieback will happen quicker on immature plants. Give it the autumn to establish the root base; it will likely die back further and grow slowly up top but once its roots are established and the weather warms up it should come back nicely. By the end of spring you will have a pretty robust plant as long as you keep up with its fertilising and watering needs.