Venus fly traps grow very slowly and even a small pot should provide plenty of room for two or three years of root development. Don't transplant newly purchased fly traps immediately--plants need time to adapt to new surroundings and the original pot gives them the best chance. Master the other issues involved -- watering, feeding and leaving the plant alone -- before shifting the fly trap to a larger or more decorative container.
Wait until winter. In early winter when daytime temperatures drop to 40 or 50 degrees F and day length shortens, Venus fly traps go dormant. Transplanting while the plants are dormant causes less stress and gives time to re-establish new root systems.
Choose a terrarium you like. Pick out something you won't be tempted to change again for years. Glass goldfish bowls work well and allow easy checks of water levels in the soil.
Mix equal parts peat moss and clean sand. Fill the terrarium one quarter full of the special soil mix. Do not add fertilizer or use pre-mixed potting soil. Fly traps obtain most of their nourishment from captured insects and do not grow well in nutrient-rich media.
Moisten the new soil by misting with rainwater or spring water. Mix the soil until evenly damp and press lightly into place in the bottom of the terrarium.
Slip the fly trap carefully out of the old pot. Tip the pot and tap the plant and soil loose. Handle the plant by the base and avoid touching the leaves. Gently crumble the old soil loose from the root ball. Shake gently to release most of the old potting mix from the roots.
Dig a small hole in the new potting soil and hold the Venus fly trap plant at the same planting level as in the old pot. Toss new soil carefully around the roots and press lightly to set the plant in place.
Water the fly trap well with the mist sprayer. Roots should be set above the layer of water that accumulates in the bottom of the terrarium, with only the lowest roots touching a constant water source. Set the terrarium in a cool place away from direct winter sunlight.