Mid-July is good time for gathering verge-side plants for dyeing with, such as cow parsley, dock and buddleia.

(left to right: Cow parsley : Buddleia 2025 : Buddleia 2025 in iron : Dock : Dock in iron modifier)
I didn't have to venture far. The hedgerows along our road are abundant with plant life.

I didn't take huge quantities - just enough for these skeins.

And with the buddleia, I prefer to leave the flowers for the pollinators and take them later in the season when they've started to brown. As they've only just started flowering here, I actually used up some I'd stored from last year.

Both the white and purple flowers give a rich buttery yellow. The colour was definitely not as strong or vibrant as with the fresh flowers. I'll be doing a proper harvest from the garden later in the year.
The cow parsley result was paler than in previous years due to gathering a smaller quantity of plant material. In previous years, it yielded an almost neon-y lemon yellow. I do prefer the more muted result.

(Note: always be careful not to confuse cow parsley with hemlock which is toxic. Cow parsley has a hollow, ridged stem with tiny hairs and is sweet smelling. Hemlock is generally a darker green and has purple blotches on the hairless stem.)
For the dock, I used mostly the seeds. Again, just a little to early in the season and I'll try again later when the plants have gone rusty for a more intense colour.

The green shades were achieved by adding to an iron bath for just a couple of minutes post-dyeing.

I like to mordant all my yarn in alum before doing any dyeing as I never know what colours it will become. Some natural dyes require mordanting and some don't depending on tannin content. This way it allows me to be more flexible knowing that it's all been mordanted.

Let me know if you're interested in trying hedgerow dyeing in the comments and I'll try and help with any questions you may have.