The Four O’Clock flower (Mirabilis jalapa) originally hails from the tropical regions of Central America. Because of those roots, she’s a bit of a “frost-phobe,” but don’t let that stop you! You can keep these beauties going for years by overwintering their tubers. You can usually snag some tubers at your local garden center, or if you’re feeling adventurous, you can start them from scratch using seeds.
Harvesting Your Own Seeds
If you’ve already got some Four O’Clocks brightening up your yard and want to expand the family, harvesting your own seeds is a total breeze. Toward the end of the blooming season, just leave the spent flowers on the plant so they can develop seeds. Once the flowers dry up, you can simply pop out the pea-sized black seeds. One quick heads-up: wear gloves! While the leaves and flowers have been used medicinally in some cultures, the seeds and tubers are highly toxic if ingested.
Sowing the Seeds
You can get a head start on the season by starting your seeds indoors on a sunny windowsill as early as March. Here’s my go-to method for success:
- Use a small file or a bit of sandpaper to gently scuff up the hard outer shell of the seeds.
- Be careful not to go too deep—you don’t want to damage the inner core!
- Soak the seeds in a cup of chamomile tea for at least 24 hours to soften them up.
- While they soak, fill your starter pots with a low-nutrient seed-starting mix.
- Plant one or two seeds per pot, about half an inch deep.
- Give them a good drink of water.
- Cover the pots with a plastic bag to create a “mini-greenhouse” effect.
- Place them in a warm spot with partial shade.
Transplanting Your Seedlings
You should see little sprouts popping up in about two weeks. If you have multiple sprouts in one pot, keep only the strongest one so it has plenty of room to develop a healthy tuber. You can start “hardening off” your young plants by putting them outside in the sun for a few hours a day. However, wait until after the last frost (usually mid-May) before moving them to their permanent outdoor home. These plants love to spread out, so make sure to give them about 20 inches of space between each other.
I wouldn’t recommend direct-sowing these seeds straight into the garden. Even if the night frosts are gone by May, the soil usually hasn’t warmed up enough for the seeds to germinate reliably.
General Care
To keep your Four O’Clocks pumping out those fragrant blooms all summer long, they really don’t need much fuss. Just make sure to deadhead (remove) the wilted flowers regularly. Only leave a few on the bush at the very end of the season if you want to collect seeds. These thirsty summer stars need plenty of water—on hot, dry days, you might even need to water them morning and evening. Toss a little liquid fertilizer into your watering can every now and then, and they’ll be happy campers!
