Water Consistently, Especially Early On
Petunias have shallow roots, so they dry out quickly—especially in a field where wind and sun exposure are high. Water new transplants deeply every few days until they’re established, then aim for about an inch of water per week depending on rainfall and temperature.
Water at the base of the plant to prevent leaf diseases, and consider drip irrigation if you’re planting a large area. Once petunias are established, they can tolerate brief dry spells, but consistent moisture during their early growth stages ensures better root development and stronger flowering later on. Don’t let all your hard planting work be undone by a dry spell!