These instructions can be used in several small scales, as you're working from an in-scale sketch rather than fixed measurements. Please visit my garden center for an overview of all my free flower DIYs and other files about making flowers.
When making lupines, make sure the sand you use has a suitable grains size for your scale. The green foam listed should work in H0 too, but for 1:48 you can use coarser foam or punched leaves. The flower supplies page has more information on supplies you can use.
Apply glue to the flowerhead area.
Dip the wire, head first, in the sand. This will give it a pointed shape.
Let the glue dry.
Paint the flowerhead.
Let the paint dry.
Add a little white to the paint, and drybrush the flowerhead. I.e., take a little paint on a paintbrush, brush it against a sheet of paper to remove nearly all of the paint, then brush lightly over the flower.
Let the paint dry.
Drybrush the tip with light green if you like.
Put a pinch of green foam on a sheet of paper and separate the bits from each other.
Apply glue where the leaves will go...
... and apply bits of foam one by one. If they're too large, tear them into smaller bits.
For a fuller effect using the same foam (e.g. in H0), apply foam by rolling the stem in it.
Let your flowers dry thoroughly before planting them.
For a grouping of the same kind of plants, you can glue greenery to the ground instead, as tall as the leaves on the plants should go. Trim the flower stems at ground level, dip in glue and stick them in the greenery.