I drink Dr Pepper in 20 ounce bottles and started seeds this way. Clean and sterilize the bottle. Then make 4 cuts on the bottle around the ridges above and below the label (2 slits on each). Picture the bottle circumference as a clock above the label slit from the 2 minute mark to the 29 minute mark and from the 31 minute mark to the 59 minute mark. Slit the ridge below from the 16 minute mark to the 43 minute mark and from the 47 minute mark to the 14 minute mark. This gives you 2 tabs on each bottle split to hold the planter cup terrarium together as the seed grows. This leaves perf tabs holding the 3 bottle parts together and providing drainage at the bottom of the cup. To fill the cup and plant the seed just fold in at the top split and scoop and fill , poke the seed in ,then re round the cone. The seedling now has a greenhouse cone over it and can be mist watered through the bottle top. when the seedling is ready for the garden, use a pair of scissors to clip the tabs of plastic holding the tops and bottoms on the bottle and transplant to the garden and slide the bottle body up as a water cup / weed control collar. The funnel top of the bottle can be reused as a mini cold fram on individually planted seeds if you want .