It has been a long standing tradition here at Estabrook's to have the pansy crop fully hardened off and out on display by the end of March or first week in April. Customers and passersby on East Main Street have always marveled at the ability of these plants to hold their colors defiantly despite the occasional white blanket of spring snow and remain unscathed by the experience.
Pansies and violas can be planted as soon as the ground can be worked and do best in mass planting using a 6 to 8 inch center. As the weather gets warmer, this spacing gives the plants mutual support against wind and rain, while providing a burst of noticeable color when perennials are just breaking dormancy.
Pansies are an environmental dream since they prefer fertilizer with a low amount of phosphorus (the middle number on formulations). Look for a feed such as 10-5-10 or 15-0-15. Keeping the phosphorus low will go a long way in reducing stretch and also win you kudos in your neighborhood for minimizing runoff.
Conscientious dead heading is essential to keeping pansies going into the warmer months. Spent flowers should be pinched back to encourage new blooms.