If acquiring Petty Spurge as a seedling in a small pot, it's best to position this pot in an area of the garden where you are happy for new seedlings to appear. This is because when the plant self seeds (and it will!) the seeds will not always drop and settle immediately below the parent plant but may also be carried up to a metre away by wind, rain or ants!
Growing from seeds requires some initial attention and patience. If growing in seed trays use a good quality seed raising mix, place the seed on top of the mix and press gently. Seedlings can appear within 7 days or may take up to 30. Patience is a virtue here as germination times can vary dramatically. If you are using a small pot then an ideal mix is 2 parts organic potting mix and one part river sand - mixed thoroughly. Place the seed(s) on top of the mix and cover lightly with a thin layer of seed raising mix - then water.
NOTE: Seeds are tiny (1-1.5mm long) so a pair of tweezers can be a very handy garden tool when placing seeds into seed trays or pots!
Sun or Shade? The plant does well in full sun but here, in Western Australia, that 'full sun' can be punishing in summer. The herb will also do well in shade or partly shaded areas although sap production is reduced somewhat, the less sun the plant receives.
Soil conditions high in PH levels are ideal and the sandier the better. The plant is not a fan of clay!
Water daily if possible. These plants like water but do not like sitting in it. In winter they should require very little attention but in summer small daily amounts of water will help them deal with those oppressive hot conditions.
Growing cycle appears to be all year round but in Western Australia they are most active in winter and spring (June - October). Being an annual, plants will drop seed then die off, often as soon as nine months.
New seedlings should be appearing in the soil around the dying plant at that stage.