Sugar-snap peas and marigolds already dance in the heads of readers who also subscribe to seed catalogs. But give a thought to artists, who supply us with color and nourishment of another sort but might have been too busy painting ceilings or wrapping bridges to think about making the deadline for the Burpee's discount. And for our spring competition, write an imaginary order for seeds, gardening supplies, etc., to plant just the right garden for any artist you choose. Would Monet have liked waterlilies in variegated colors? And would Jackson Pollock have appreciated a drip irrigation system? Here's your opportunity to help out. Send one artist's garden order per entrant, please, at no more than 100 words, to The Home Forum Competition, The Christian Science Monitor, One Norway St., Boston, MA 02115. Only orders received by March 13 can be considered for announcement of award certificates March 31. Sorry, none can be returned.