Cut the plastic container in half and set aside the bottom half; discard the top half.
Mix your potting soil to propagate the desert plant and fill the plastic container half full. Compose the potting mixture of 1 part perlite with 1 part vermiculite and a pinch of osmacote fertilizer.
Sow desert plant seed and water thoroughly, soaking the soil.
Cover the bottle with plastic wrap and place in a cool but well-lit area.
Remove plastic cover when seeds begin to germinate and keep well watered.
Divide plant as desired and transfer the young desert plants to small flower pots once growth is consistent.
Create the same planting mixture used for propagating seeds: 1 part perlite with 1 part vermiculite and a pinch of Osmacote fertilizer.
Place the soil mixture in the plastic bottle and add the cutting, placing it stem-first into the soil. Place it deep enough so that it will not fall over; the roots need to anchor the plant in the soil.
Water the soil thoroughly and cover with plastic to maintain humidity. Keep the cutting in a well-lit area to spur growth.
Transfer the cutting to a small plastic pot once new growth is observed and continue to keep the new cutting well watered for the first month.