Fig 19-26. Map showing regions of sufficient winter and spring flower bud formation for a commercial crop in southern states and in California. In the cross-lined area spring flower bud formation usually or always occurs with some varieties. The series of lines along the border of this area in the South represents areas where winter and spring fruit bud formation occurs in years of mild winters. In the cross-lined area of California, fruit bud formation continues throughout the summer in some varieties. Though occasionally flower buds form in early spring as far north as Washington, D.C., most flowers are sterile and no commercial crop occurs.