How to Grow Four O’Clocks

I first saw four o’clocks on a list of flowers that bloom through Arizona summers. I didn’t know how to grow four o’clocks but thought – hey, if they can bloom through the summer here in the low desert, I need to give them a try. 

The list was right! I planted four o’clock seeds and was rewarded with beautiful blooms from mid-summer until temperatures cooled off in the fall. I now plant these flowers each summer in my garden and enjoy the bright colors and pollinators they bring to the garden. 

I’m sure you’re wondering (as I did) why are they called four o’clocks? They got that name because the trumpet-shaped flowers bloom in the late afternoon (even later if it’s very hot) and stay open until the following morning. Interested in learning how to grow four o’clocks? Keep reading for my best growing tips. 

5 Tips for How to Grow Four O’Clocks

1. Plant four o’clocks from seed directly in the garden

This native of tropical areas in North and South America is a perennial in very warm climates but is often grown as an annual in most parts of the United States. Four o’clocks grow easily from large black seeds. One of the most common varieties is “Marvel of Peru”—it has multi-colored blooms of pink, red, yellow, and white all on the same plant. I’ve had success with these seeds from Botanical Interests. 

2. Choose the best location for growing four o’clocks

Four o’clocks grow best in well-draining, compost-rich soil. Plants often sprawl and can be 2-3 feet tall and 1-2 feet wide. Larger plants do best with some support as the branches are very brittle. 

Four o’clocks thrive in areas with plenty of sunlight, but also grow in partial shade. In hot climate areas like the low desert of Arizona, a little afternoon shade is preferred. 

My favorite spot for growing four o’clocks is at the corners of my raised beds. I tuck a seed or two in the corner, and the plant spreads over the side and adds color to my garden. Planting them in the corners means they don’t take up much room in the beds. You can also plant four o’clocks as a border or in containers.

3. Plant four o’clocks at the right time

Four o’clocks prefer warm soil, and a good rule of thumb is to plant seeds around the same time you plant tomatoes. Here in the low desert of Arizona, plant four o’clocks from March through June. You can expect blooms from July through November. 

For square foot gardening, allow 2 square feet per plant. 

The Perpetual Annual Flower Planting Calendar, available in my shop, helps you learn when to plant flowers in the low desert of Arizona and whether to plant seeds or transplants.

4. Care for four o’clocks as they grow

Growing four o’clocks couldn’t be easier. They really are a plant-it-and-forget-it type of plant. Give them regular water and keep the soil evenly moist. Feeding throughout the growing season will encourage more blooms, but isn’t necessary.

5. Save seeds or “bulbs” to plant the following season

After blooming, the tubular four o’clock flowers develop into large black seeds. It’s easy to collect and save the seeds to plant the following season. Seeds may drop and re-seed easily as well. 

During the course of the season, four o’clocks also form a bulbous root (similar to a potato). If you live in a mild-winter climate, the bulb can be left in place to continue growing the following season. In cooler areas you can lift the bulb and replant in the spring.

Be aware that all parts of the plant (including the seeds and bulb) are toxic.

Get planting dates for your favorite crops with these visual planting guides for vegetables, herbs, fruits, flowers & vines.

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