Most seed production is completed by late July or August. However, flowering and seed formation can continue until the first freeze kills the inflorescence. Flowering stalks of leafy spurge produce from 10 to 50 three-lobed capsules. The capsules, which usually contain three seeds, explode when dry, projecting seeds as far away as 15 feet from the plant. An average of 140 seeds is produced per stem.
Seeds can remain viable for as long as eight years in the soil.
The peak period of germination is late May and early June, but seeds can germinate throughout the growing season. The large seed reserve in the soil and seed dormancy enables an established stand of leafy spurge to survive repeated control attempts. Water, birds, animals and man efficiently disperse the seed to start new infestations. The extensive root system makes leafy spurge difficult to control. Leafy spurge roots are most abundant in the upper foot of soil, but can grow as deep as 15 feet.