Again I'm using IZZY from Di's Digi Downloads
The colours I've used here are....
COOL GREY 1
COOL GREY 3
COOL GREY 5
STEP 1 - Underneath your image use the COOL GREY 1 to colour in quite a large area, try to imiagine how the shadow would look in real life so make it wider where the image is stood gradually going up to a narrow bit at the top. Cool Grey 1 is very very light so it won't matter a jot if you make a mistake here plus you'd usually be trimming it down to add to your card so go wild!
*NB I've editted the photo a little darker so you can see it better
STEP 2 - Add some COOL GREY 3 now leaving a larger shadow
STEP 3 - Add a smaller bit of COOL GREY 5 directly under the points that are touching the floor
STEP 4 - Use your COOL GREY 1 and colour over the entire greys to blend them all together.
STEP 5 - This bit is optional but whilst your ink is still wet from blending all the greys in from step 4 use your COOL GREY 5 again and with a light hand re-add it. As the ink is still wet it wont be as harsh a line as you see on step 3.
ADDING SOME GRASS GROUNDING
You can use lots of combos for grass depending if you want it looking green and lush or more summery, its the same principal of using a light, a mid and a dark so here I chose my favourite grass combo of LIME ZEST, PEAR GREEN AND OLIVE GREEN
STEP 1 - Same as for the grey, add a shadow underneath using LIME ZEST
STEP 2 - Add in your PEAR GREEN as Step 2 above
STEP 3 - And again like step 3 above add in your OLIVE GREEN
STEP 4 - As above blend in your greens using the LIME ZEST
STEP 5 - As above, whislt the ink is still wet use a light hand to add in more OLIVE GREEN underneath the points that touch the floor. You can leave it as is or continue and add some flicks of PEAR GREEN to make some grass blades
STEP 6 - Add a few blades of OLIVE GREEN here and there then give it all a once over with the LIME ZEST and repeat step 5 and 6
You can take your time more with this and use the Letraset Fine Nibs to add more pronounced blades and greater shadows :)