Before discussing regional timing, you must understand my fundamental requirements as a plant. I am a tender perennial, often grown as an annual in colder climates. My roots and foliage are highly susceptible to damage from frost and cold, wet soil. I thrive in conditions that offer full sun and very well-draining soil. The single most critical factor for my successful outdoor transition is consistently warm soil temperature. Planting me outdoors should only occur after any danger of frost has completely passed and the soil has had a chance to warm up significantly. A chilly, damp start will stunt my growth, leave me vulnerable to rot, and delay my flowering.
In these regions, including areas like Southern California, Florida, and the Gulf Coast, I can be treated as a true perennial. Here, you can plant me outdoors very early, typically from late February through March. The soil warms up quickly, and the risk of a hard frost is minimal. This extended growing season allows me to establish a strong root system before the intense summer heat arrives. In the warmest parts of Zone 10-11, I may even bloom for you throughout the entire winter. The primary consideration in these areas is providing adequate water during the hottest, driest periods and ensuring exceptional drainage to prevent root issues during humid spells.
This is a large and varied band across the US, encompassing the Mid-Atlantic, parts of the Pacific Northwest, and lower Midwest. Here, the timing for my outdoor planting is more cautious. The target window is mid to late April, but you must be vigilant. A late spring frost can still occur. It is wiser to wait until the soil is no longer cold and soggy from winter rains. Warm days are tempting, but cold nights can shock me. Let the weather stabilize. If an unexpected cold snap is forecast after planting, be prepared to cover me with a frost cloth or bucket overnight for protection.
In these regions, including the Upper Midwest, Northeast, and high-elevation areas, patience is absolutely essential. You must wait until late May or even early June to plant me outdoors. The ground takes much longer to warm up, and the last frost date arrives significantly later. Rushing to plant me on a warm day in early May could be disastrous if temperatures plummet the following week. In these zones, I will perform strictly as an annual. The goal is to get me into the ground as soon as it is safely warm enough to give me the longest possible period to grow and flower before the first fall frost ends my season.
This region requires careful attention to microclimates. In lower, desert areas (Zone 7-9), you can follow the guidelines for the Temperate South, planting in early to mid-spring. However, in higher elevation areas like the Rockies or Sierra Nevada (Zones 4-6), you must adhere to the rules for colder northern climates, waiting until late May or June. The intense sun at high altitudes is ideal for me, but the nights remain cold for a long time. The key is to monitor local frost advisories diligently and ensure the soil is workable and warm, not frozen or waterlogged from snowmelt.
