Annual plants provide immediate, continuous bursts of color, completing their entire life cycle within a single growing season. This characteristic offers reliable vibrancy and the flexibility to change garden designs every year. Deciding what annuals can be planted right now depends entirely on your local climate and the specific temperature preferences of the plant varieties. Understanding these environmental factors is the first step toward maximizing your garden’s display.
Understanding Your Planting Window
The question of what to plant “now” hinges on your average last expected frost date. This date serves as the primary dividing line for when it is safe to introduce different categories of annuals. Annuals are broadly separated into two groups based on their ability to withstand cold temperatures.
Cool-season annuals are tolerant of light frost, meaning they can typically be planted several weeks before the last frost date, flourishing in the milder temperatures of early spring and fall. Warm-season annuals are sensitive to cold and require the threat of frost to be completely gone before planting. Introducing these tender varieties too early can lead to stunted growth or plant death.
The temperature of the soil is often a more significant factor than the temperature of the air for successful establishment. Cool-season annuals can establish roots in soil temperatures as low as 40 to 50 degrees Fahrenheit. Warm-season annuals, however, require a soil temperature consistently above 60 degrees Fahrenheit for robust growth. Using a simple soil thermometer clarifies if conditions are ready for planting.
Cool-Season Annuals Ready for Planting
In early spring, the immediate options are the cool-season annuals that flourish when temperatures are mild and the soil is still cool. These plants withstand the dips in temperature that occur before summer arrives. Planting these varieties now ensures an early splash of color that lasts until the heat of summer causes them to fade.
Pansies (Viola x wittrockiana) are celebrated for their wide array of colors and the ability to tolerate temperatures several degrees below freezing. They perform best when daytime temperatures are between 55 and 75 degrees Fahrenheit. Regular removal of spent flowers, known as deadheading, encourages continuous blooming throughout the cool spring season.
Violas, the smaller cousins of pansies, exhibit even greater cold tolerance and often continue to bloom profusely through light snowfalls. Snapdragons (Antirrhinum majus) withstand light frosts and provide a unique vertical element. Snapdragons often experience a lull in flowering during the summer heat but will resume blooming when cooler temperatures return in the fall.
Ornamental cabbage and kale are prized for their striking foliage, which intensifies in color as temperatures drop below 50 degrees Fahrenheit. These varieties can survive temperatures as low as 5 degrees Fahrenheit, making them durable for early or late-season displays.
Calendula (Calendula officinalis) prefers the chilly side of the temperature spectrum. Its bright yellow or golden flowers bloom vigorously until hot summer conditions cause them to cease production. These hardy annuals offer an easy-care, vibrant option for gardeners seeking immediate color.
Warm-Season Annuals to Prepare For
While cool-season varieties are ready for immediate planting, many popular summer annuals must wait until the threat of frost is entirely absent and the soil is sufficiently warm. Planting these heat-loving varieties too soon can shock the root system. The optimal time for planting these tender annuals is typically two to three weeks after the average last frost date.
Petunias are a ubiquitous choice known for their long-lasting, abundant blooms, but they are susceptible to damage from temperatures at or below freezing. They are best planted when the soil has warmed. Petunias prefer full sun and are highly adaptable to both garden beds and hanging baskets.
Impatiens (Impatiens walleriana) are favored for their ability to thrive in shaded locations where many other flowering annuals struggle. They require moist, well-drained soil and need consistent warmth for healthy growth. Zinnias are heat-tolerant plants that require full sun and soil temperatures of at least 60 degrees Fahrenheit for optimal germination and growth.
Marigolds (Tagetes species) provide reliable color in shades of yellow and orange, thriving in full sun. They are easy to grow and can be direct-seeded into the garden once the soil temperature reaches approximately 65 degrees Fahrenheit. Starting seeds indoors now allows for a seamless transition once the weather warms.
Ensuring Successful Establishment
Once the appropriate annuals for the current weather window have been selected, certain steps ensure a smooth transition from the nursery pot to the garden environment.
Hardening Off
For all annuals purchased from a greenhouse, hardening off is necessary before planting them directly outside. This involves gradually exposing the plants to outdoor conditions—sunlight, wind, and temperature fluctuations—over a period of about seven to ten days.
Soil Preparation
Proper soil preparation at the planting site is important for immediate root establishment. Amending the planting hole with organic matter, such as compost, improves soil structure. This ensures the soil retains moisture while still allowing for adequate drainage.
Initial Watering
After placing the plant in the ground, ensure the top of the root ball is level with the surrounding soil. A thorough initial watering is needed to settle the soil around the roots. This deep watering eliminates air pockets and establishes good contact between the roots and the surrounding soil medium. Focusing on this initial establishment phase sets the stage for vigorous growth.