Four O'Clock got its name because it typically blooms late in the afternoon. It is among the most colorful, fragrant, and robust of all flowers that can be grown from seed. Seeds can be sown directly into the soil or into pots or other containers such as barrels. Plant seeds in the spring for late summer/early autumn blooms.
Blooms are toxic to children and pets if ingested.
Four O'Clock seeds require scarification prior to planting. This is a simple process that involves nicking the seeds with a knife or rubbing them with sandpaper or a file.
To assist germination, soak the seeds overnight in warm water before sowing. Stratification and light will improve chances of germination. Four O'Clock seeds require light to germinate, so be careful not to cover them when planting (use about one quarter inch of soil to cover seeds). Plant one quarter inch deep. These seeds are larger than most that require sunlight, so they shouldn't be surface sown. If starting indoors, start 8–10 weeks before the last frost.
Wait until blooms are spent and dry; flower heads will drop off of the plant. A day or two after the flower has dropped off, a small green seed will be visible. Don’t pick these until the full dark color is observed (usually a day or two after the green seed becomes obvious). Snip off the seed head and gently remove any green plant tissue from the dark seed. Lay the seeds flat and allow them to dry for three to four days before storing them in a cool, dry area for up to two years.