The second area that comes to mind strongly, is the permanent way outside the station limits.Generally, the area of land over which the railway passes, is under the control of the railway, but the only part of it to be actively managed by the railway is that portion under and in the immediate vicinity of the tracks.

By and large, the remainder is simply left to its own devices. While much of it is likely to be low grasses, there will also be clumps of taller grass (where various of the tufts such as NO07004, NO07022, NO07027, NO07032 can be used effectively, while other tufts which simulate flowering plants, can be used more sparingly. NO07014, for example, has four different, muted colours, with 52 clumps of 6 mm. high and 46 clumps of 12 mm. high. 

Apart from that, consider also, use of Foliage. 'Foliage' in model railway terms, is a Razor-thin and highly flexible substrate.The foliage is flocked with up to five different materials, in conjunction with electrostatic flocking. This guarantees the natural appearance of NOCH Foliage. Simply put, take a piece of Noch foliage (NO07270; NO07271; NO07272; NO07280; NO07281; NO07282; NO07290; NO07291; NO07292 NO07300 & NO07301); tear it into the rough shape you require and secure it into place on your layout. It will resemble a clump of low-level bushes - of the types that quite frequently inhabit the spaces alongside the permanent way. 

Finally, consider the buildings and fences the mark the edge of the permanent way. There will usually be a range of plants, flowering or otherwise, that inhabit the boundaries of the permanent way, usually hard up against a fence or commercial building. Here, frequently, quite tall plants can found  and here is where it is suggested that you let your imagination run riot, with tufts that have coloured tips to them.

My final exhortation to you is to go to your local railway line; take a trip (if possible) on a local railway service and observe, observe, observe, the vegetation that you see.