One week in advance, make leaves.
Tape two 18-guage wires together to form stem. Repeat for a total of six stems. Set aside.
Using Leaf Green icing color, tint gum paste medium green. Roll out gum paste to 1/8 in. thickness. Using craft knife, cut out two 7 in. hearts. Using craft knife, cut out grooves in leaves.
Place leaves in cornstarch-dusted curved bowls or containers. Prepare gum glue adhesive following recipe instructions. Brush gum glue adhesive down center of back of leaf; position stem. Cut small strip of gum paste, wet back with edible adhesive, position on top of stem to adhere to leaf. Let dry 48 hours, moving leaves occasionally to avoid sticking to the pan.
Remove from pan; let air dry completely.
Repeat four more times, making two 3 in. to 5 in. leaves and two 6 in. leaves, for a total of six leaves.
Once all leaves are completely dry, dust edges with Spruce Green Color Dust.
Bake cakes.
Prepare cake batter following recipe suggestions. Using 6 in. round pan, bake and cool three cake layers. Trim one layer to 1 in. high for 5 in. high tier.
Cut two cake boards to 8 in. x 8 in. squares.
Using 8 in. square pan, bake and cool four cake layers. Fill and stack two 4 in. cake layers on cake boards.
Prepare buttercream icing following recipe instructions.
Place dowel rods in bottom 4 in. cake layer. Stack second 4 in. cake on top, for 8 in. high tier.
Spatula ice 6 in. round tier and 8 in. square tier. Prepare cake for stacked construction.
Make bamboo.
Roll 1 oz. fondant into 8 in. log. Using ball tool, flare ends. Using knife tool, score bamboo, making two marks around entire bamboo stick, measuring 1/8 in. apart. Repeat for a total of 3 to 4 markings.
Repeat, making a total of 10 bamboo sticks.
Thin Bronze Pearl Dust with Lemon Extract. Using decorating brush, paint around score marks on each bamboo stick.
Thin Gold Pearl Dust with Lemon Extract. Using decorating brush, paint rest of bamboo sticks. Let dry, about 10 minutes. Using buttercream icing, attach to edges of square cake.
Insert leaves.
Place small amount fondant inside three flower spikes. Insert flower spikes into top of 6 in. tier. Insert gum paste leaves into flower spikes.