I model on the cheap.  I make all my own ground scatter (flocking) out of either sawdust that gets coloured in the electric coffee grinder my wife gave me for modeling, or foam rubber done same way in the coffee grinder.  That way you can control the colours and the granularity of your finished product.  I also make my own iron oxide (rust) by soaking about 4 pieces of 0000 steel wool in a quart jar with white vinegar.  After about a month sitting in the window, I pour the mixture into a large pan (I use my old 11" x 14" stainless steel photo fixer trays when I had a darkroom) or baking dish and wait for the mixture to completely dry (usually about 2 to 3 weeks).  Then I take a single edge razor blade and pulverize the contents into a fine powder and store it in little tins.  Each batch I've done comes out a little different in colour.  Then you use the rust as you would any weathering powder or chalk.  It looks real, 'cause it IS real rust!  I also colour my own chalk with acrylic  paint and food colouring.  I never buy weathering powders.  Instead, I go to the dollar store and buy women's makeup in the little plastic containers.  For $1.00 you can get quite a collection of different colours and they adhere better than weathering powders.  
For trees, I use the Nandena bush after the little red berries fall off, it leaves a perfect tree trunk (armature).  I also have a TON of lichen growing out back on the hill behind my house.  When using the Nandena bush tree armatures, you can paint them whatever colour you want--even grey for aspen trees.  Cover the armatures with lichen, seafoam or whatever you want, then add your own home-made flocking and you're done. For pine trees, I use florist wire (wrapped) doubled and bits of jute cut in 1 to 1 1/2" laid in the wire, then using a drill, twist the wire while holding the other end in a pair of pliers..  I also use barbeque bamboo skewers with pig hair (horse hair) furnace filters (they're already green); have to paint the skewers first.  And I never use spray paint since I use my airbrush for all my painting.  I can use either acrylic or oil base paints; I usually use one airbrush for acrylic and the other one for oil base paints.  Cheers from W Rusty Lane K9POW in eastern Tennessee

Great. I'm going to have a go.thanks.

I can just about comment as my fingers are covered in spray glue trying to make bushes. This is a brilliant idea, I’m off to pull some cushions apart! 👍

A top tip! When I was working in T gauge, as it's so small, i'd get a cocktail stick, paint it dark brown and glue a couple clumps of foliage on - looked very convincing for the scale!

Very nice. Great tip! Thanks for sharing

another great video, thank u

Thankyou for the video and tips

Gave your bushes ago. Good results, thanks for the tip. Regards Graham 👍

Nice work!

Brilliant ! well done mate.

Hi am into 0 Gauge I have had a go using  hair  spray having a look at yours I well try white glue instead great video too

Brilliant, made some of these but I made my own flock with sawdust and acrylic paint from another YouTube vid if your still about 👍🏻 ty sir

Cracking good idea, very useful video.Richard

great idea, I have just spent ages looking for cheap bushes and with this, I feel like I have struck gold! definitely using this idea!

Very nice.  Thanks for sharing.  -Rick

Genius

👍

Very good method. Thank you for that.

I have been wanting to do a diorama of a sherman tank in the Hedge rows in Normandy this will work thank you for the tip Bruce

Interesting concept thanks for sharing