Grow Four O’Clocks From Seed

What Are Four O’Clocks

Four O’Clocks grow as a shrub like plant with medium green foliage and bright trumpet shaped flowers. You can grow them from seed or tubers. The flowers are very attractive to Hummingbirds and many other pollinators. Four O’Clock blooms open in afternoon, giving them their name. The flowers will stay open all night and close in the morning.

Four O’Clocks From Seed vs. Tubers

grow four o'clocks from seed vs. tubers

Four O’Clock plants grow from a carrot shaped tuber from which the foliage sprouts. Known as a tender perennial, these plants are hardy in zones 7-10 although I’m in zone 6b and they grow back each year. 

If you’re outside the hardiness zone the tubers can be dug up and stored until the following growing season. 

For a more economical method you can grow Four O’Clocks from seed. The seeds are very large and resemble raisins. If you already grow them in your garden, you’ve probably seen the large seeds in the center of spend blooms.

Four O’Clock seeds can be purchased or you can collect your own seeds from existing plants. If you’d like to increase the amount of Four O’Clock in your garden then propagating from seed will be the most cost-effective solution.

grow four o'clocks from seed

Collecting Seeds from Four O’Clocks

Four o’clocks produce only one seed per flower. The seeds are quite large, about a 1/4″ in diameter. Once the flower dies away it will leave the large dark brown seed sitting in the sepals, the green pedal like parts at the base of the flower. The seeds will be sitting loosely in the sepals and will fall out if you simply turn the sepal’s upside down.

The easily dropped large seeds, which resemble raisins, are likely the reason Four O’Clocks readily reseed themselves which can be beneficial if you’re outside the hardiness zone for the Four O’Clocks. 

Collecting and planting the Four O’Clock seeds is another way to ensure you’ll be able to enjoy these lovely flowers year after year.

Four O’Clock plants can either be direct sown or started indoors prior to spring. My personal experience with growing them from seed is a germination rate of about 80%. That said, whether you decide to direct sow or start the Four O’Clocks indoors I’d recommend placing at least 2 seeds in each location to increase the likelihood of at least one seedling in each desired planting area or flowerpot.

Grow Four O’Clocks From Seed – Outdoors

If you decide you’d like to direct sow the seeds in your garden it is recommended to plant them in the spring a couple weeks after the last frost date. Plant the large seeds in an area that receives full sun about 1/4″ deep and about 12″ apart. 

Soaking the seeds in water overnight before planting will help speed up germination. You should see your seedlings emerging in 7-14 days. Using the direct sowing method will result in the plant flowering much later in the season. In order for the plants to reach maturity faster you should consider starting the seeds indoors 6-8 weeks before spring.

Grow Four O’Clocks From Seed – Indoors

grow four o'clocks from seed seedlings with true leaves

When sowing Four O’Clocks, or any seed, always use a good quality sterile seed starting media, such as Espoma Organic seed starting mix. Moisten the soil before adding to the desired container, I prefer to start the seeds in a 6-cell seed pack. Soil should be moist but not wet. You should barely be able to squeeze water from the soil.

Four O’Clock seedlings can grow large quickly, as such you may choose to start the seeds in a 3″ pot. Sow seeds at a depth of about 1/4″ or so and put your container under a humidity dome to help ensure good germination. Germination should occur within 7-14 days.

My personal experience with starting the Four O’Clock seeds in loose seed starting mix is that the seedlings don’t shed the seed hull as easily. This is called “helmeting” and the seedling may require assistance removing the hull. 

If the seedling doesn’t shed the hull soon enough the stem will grow excessively tall. The leaves are searching for light thinking they haven’t breached the soil surface. Since the seeds are so large the hull is easy to remove. 

Using your thumbnails just spread the halves of the hull. Just be careful not to damage the confined cotyledons. I’ve performed this several times and never had any problems with damaging the sprout.

grow four o'clocks from seed

Caring For Four O’Clock Seedlings

Once the seeds have germinated the humidity dome can be removed. Just be sure the seedlings don’t completely dry out after the humidity dome is removed. 

The seedlings will also need light at this point. When germinating outdoors indirect light would be best for the first few weeks.

When growing seedlings indoors a fluorescent light fixture works great until the seedlings can be transplanted outdoors. Fluorescent fixtures are great because you can use standard fluorescent bulbs or LED retrofit bulbs. 

Use bulbs with a spectrum between 5000k-6500k for starting seedlings. This ensures proper growth of the foliage and roots. 

Transplant the Four O’Clock seedlings to a larger container once the seedlings are about 2-3 weeks old and the first set of true leaves have formed.

Transplanting Four O’Clocks Outdoors

As always, harden off any seedlings by giving them more and more direct sunlight before exposing them to full sun. These are tender plants outside of zone 7-10 so plan to transplant outside well after all risk of frost, about the same time you would plant tomatoes. Choose a location with full sun, although the Four O’Clocks will tolerate some shade, and loosen the soil to a depth double the starting container before planting. Space the plants about 12-18″ apart.

Four O’Clocks are a beautiful addition to any garden. They make great borders and work well in containers on your deck or patio. Four O’Clocks can also be used to add color to a partially shaded area of the garden with hostas or the other primarily green foliage.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses cookies to offer you a better browsing experience. By browsing this website, you agree to our use of cookies.