while most avid gardening enthusiasts will claim you can make a cutting and stick it in the ground to propagate, its a hit and miss for me.
sometimes I do that if I'm busy.
A higher chance of rooting is to give it more time to grow roots, especially if you intend to help someone start off with their portulaccas.
First, cut a small square of cotton wool and aluminium foil. Dampen the cottonwool. Placethe cuttings on the cotton wool. Remove the tiny leaves from the areas where you'd like roots to form.
Fold the damp cottonwool square into half to allow contact with stem. This is the only source of nourishment – no fertiliser needed for the next 7 days. If cottonwool dries out during warm weather, soak it into water. This is my 7 yr old niece's finger, so you can gauge size of the cottonwool square. I prefer not to put too many cuttings on a square to allow closer contact between cottonwool and the stems.
Fold the aluminium foil in half, same way as the cotton wool in earlier picture, and roll over. Set it in a cool place for 7 days and roots should form by then. Another simpler method is to just stand the stems in water (sans cotton wool and aluminium foil) but its not worked for me with portulaccas. The stems tend to absorb too much water and get mushy.
Open the package after 7 days, and stick the stems with tiny roots in the soil. Pat down and water generously.