If you live in Luxembourg, I would not recommend to visit just the lavender farm in Belgium, simply because it is too small and you might be a bit disappointed. BUT if you pair it with another thing to visit in that area or you are passing from the Netherlands as we had, the Limburg Lavendel Farm is a place where you can experience a bit of Provence (I know Provence is more than the lavender, don't even bother).
The farm has 4 hectares (on paper), it has a shop from where you can buy everything lavender related, it has a coffee shop from where I recommend you try the lavender ice-cream and it has the field which is free to visit. By the time we arrived at the farm it was the middle of the day and everyone was more focused on looking for the shade of the trees and not pictures with the flowers, but nonetheless it was a nice experience. We ate an ice-cream, took some pictures and went on our way. The farm has an ample parking space which is as well free.
The farm also has a garden where you can explore other different types of lavender and one of those is this yellow lavender. I wonder if I could buy it from somewhere in Luxembourg and also if it survives here.
They also have small lavender plants to buy, but only the type from their field, not the ones in the garden.
Oh yes, there is also this weird sculpture, art of some sort, which frightened Luna and us with her. You will see a lot of sculptures in the garden and the lavender field, but they are more eye appealing than this one :)
And YES dogs are allowed on the farm/field, but on the leash.