The Mirabilis jalapa, commonly known as the Four O’Clock or Marvel of Peru, features fragrant, trumpet-shaped flowers. This tender perennial is frequently grown as an annual in cooler climates, offering a continuous display of blooms from midsummer until the first frost. The plant earns its common name because its flowers reliably open in the late afternoon, typically around 4:00 p.m., releasing a sweet scent that attracts nocturnal pollinators. Growing these plants from seed is a straightforward process, provided the gardener addresses the specific requirements of the seed before planting.
Preparing Four O’Clock Seeds for Planting
Four O’Clock seeds possess a naturally hard outer shell, which prevents moisture from reaching the embryo and thus inhibits germination. This protective layer must be compromised to break the seed’s physical dormancy and ensure successful sprouting. The recommended preparation method involves a two-step process: scarification and soaking.
Scarification
Scarification means physically weakening the seed coat. This is accomplished by lightly rubbing the seed with fine-grit sandpaper or carefully nicking the shell with a small knife or nail clipper. The goal is to create a small opening without damaging the inner seed material, allowing water to penetrate the thick shell.
Soaking
Following scarification, soak the seeds overnight in warm water to hasten the germination process. Soaking softens the remaining seed coat and begins the internal hydration process, which significantly reduces the typical 7- to 14-day germination period. After soaking for 12 to 24 hours, any seeds that have visibly swelled are ready for immediate planting.
Selecting the Right Time and Location
Timing the sowing of Four O’Clock seeds depends on the local climate, as the plants are tender and highly susceptible to frost damage. Direct sowing outdoors should only occur after the final expected frost date has passed and the soil temperature has warmed consistently. A soil temperature range of 65–75°F (18–24°C) is ideal for prompt germination.
In regions with shorter growing seasons, starting seeds indoors four to eight weeks before the last frost date is effective. When starting indoors, the young plants must undergo a “hardening off” period before being transplanted outside. This involves gradually acclimatizing the seedlings to outdoor conditions, like sun and wind, over about a week to prevent transplant shock.
The chosen location should provide full sun (at least six hours of direct sunlight daily), although Four O’Clocks can tolerate partial shade. In extremely hot climates, afternoon shade can be beneficial to prevent scorching. While the plant is adaptable to various soil types, it thrives best in well-draining soil that has been enriched with organic matter, such as compost.
Mechanics of Sowing the Seeds
Once the seeds are prepared and the outdoor conditions are suitable, the sowing process is straightforward. Sow the prepared seeds approximately 1/4 to 1/2 inch deep in the soil or starting mix. Planting them too deeply can hinder germination.
When sowing directly into the garden, place the seeds about six inches apart initially to allow for successful germination. Because the mature plants develop into bushy, multi-branched shrubs, they require significant space later. After placing the seed, gently firm the soil surface over the planting area and water thoroughly. This initial deep watering settles the soil around the seed, ensuring good seed-to-soil contact.
Essential Post-Germination Care
After the seedlings emerge, typically within one to two weeks, consistent maintenance is necessary to promote robust growth. Thinning is important for direct-sown seeds; remove the weaker seedlings to give the remaining plants adequate room to grow. The final spacing for mature plants should be between 12 to 24 inches apart, depending on the variety and desired bushiness.
Four O’Clocks require regular and deep watering, especially during dry spells and in their early growth stages. The soil should be kept consistently moist but never waterlogged, as overly saturated conditions can lead to root rot. While these plants are tolerant of poor soil, they are considered heavy feeders and benefit from an occasional application of a balanced, slow-release fertilizer or a high-potassium formula designed for flowering plants.
To encourage continuous production of their fragrant blooms throughout the summer and fall, spent flowers should be removed through deadheading. Deadheading prevents the plant from diverting energy into seed production, prompting it to instead produce new flower buds. The plants are generally resistant to most pests and diseases, simplifying their overall care routine.