Understanding when to plant 4 oclock seeds is the first step to enjoying their vibrant, fragrant blooms. Four o’clock seeds should be sown only after the soil has warmed sufficiently in the spring. Planting them at the right time ensures strong germination and a long, prolific flowering season that lasts until fall.
These charming flowers, botanically named *Mirabilis jalapa*, are beloved for their trumpet-shaped blossoms that open in the late afternoon. They are remarkably easy to grow from seed. This guide provides clear, step-by-step instructions on timing, planting, and care so you can succeed in your garden.
When To Plant 4 Oclock Seeds
The ideal planting time hinges on one critical factor: soil temperature. Four o’clocks are tender perennials often grown as annuals. They originate from warm climates and will not tolerate cold, damp conditions.
Seeds planted in cold soil will likely rot before they ever sprout. Waiting for the right warmth is non-negotiable for good results.
Key Factors For Determining Planting Time
You should not rely on the calendar date alone. Instead, assess these three environmental cues to choose the perfect sowing day.
Your Local Average Last Frost Date
This is your foundational reference point. The average last frost date marks the end of typical freezing temperatures in your area. You can find this date through local extension services or gardening websites.
- For direct sowing outdoors: Plant your four o’clock seeds 1 to 2 weeks after this date.
- For starting seeds indoors: Begin the process 4 to 6 weeks before the last frost date.
This staggered approach ensures young plants are ready to go outside just as the weather becomes favorable.
Soil Temperature Is The Most Important Cue
This is the most reliable indicator. Four o’clock seeds germinate best in warm soil.
- Optimal Soil Temperature: A consistent 65°F to 75°F (18°C to 24°C).
- Minimum Soil Temperature: Do not plant if soil is below 60°F (15°C).
You can measure soil temperature with a simple soil thermometer. Insert it about 1 inch deep in the planting area at midday for several consecutive days to get an average.
Regional Planting Windows
Your geographic location dictates a general planting window. Here is a basic regional guide:
- Southern Climates (Zones 8-10): Can plant as early as March or April. Seeds can often be sown directly outdoors.
- Middle Latitudes (Zones 6-7): Aim for late April to mid-May for indoor starts, with transplanting or direct sowing in late May.
- Northern Climates (Zones 4-5): Wait until late May or early June for direct sowing. Starting seeds indoors in mid-April is highly recommended.
Always temper these guidelines with your actual soil temperature readings and current weather forcasts.
Starting Four O’Clock Seeds Indoors
Starting seeds indoors gives you a head start, especially in regions with short summers. It allows you to have robust seedlings ready to plant as soon as the outdoor conditions are perfect.
Begin this process 4 to 6 weeks before your expected last frost date.
- Choose containers with drainage holes. Cell packs or small pots work well.
- Fill them with a sterile, lightweight seed-starting mix. Do not use heavy garden soil.
- Moisten the mix thoroughly before planting so it’s damp but not soggy.
- Plant the seeds about 1/4 inch deep. Place one or two seeds per cell.
- Cover the seeds lightly with the mix and gently firm the surface.
- Place the containers in a warm location. A heat mat set to 70°F is ideal for germination.
- Keep the soil consistently moist but not waterlogged. A spray bottle is useful for this.
- Seeds typically germinate in 7 to 14 days. Once sprouts appear, move them to a bright, sunny window or under grow lights.
Hardening Off Seedlings
This is a crucial step that cannot be skipped. Indoor-grown seedlings are tender and need to acclimate to outdoor conditions like sun, wind, and temperature fluctuations.
- Begin about 7-10 days before your planned transplant date.
- Place seedlings in a sheltered, shady spot outdoors for just 1-2 hours on the first day.
- Gradually increase their time outside and their exposure to direct sunlight over the week.
- By the end of the week, they should be staying outdoors overnight if temperatures are mild.
- Now they are ready for planting in their permanent garden spot.
Direct Sowing Four O’Clock Seeds Outdoors
Direct sowing is the simplest method if you have a long growing season. It avoids transplant shock and is less work. Wait until all danger of frost has passed and the soil is genuinely warm.
- Select a site with full sun to partial shade. Four o’clocks bloom best with at least 6 hours of sun.
- Prepare the soil by loosening it to a depth of about 8-12 inches. Remove weeds and rocks.
- Incorporate some compost or aged manure to improve drainage and fertility. These plants are not picky but thrive in moderately fertile soil.
- Plant the seeds about 1/4 to 1/2 inch deep. Space them 12 to 18 inches apart, as plants can grow quite bushy.
- Water the area gently but thoroughly after planting.
- Keep the soil moist until germination occurs. Seedlings should emerge in 1 to 2 weeks.
- Once seedlings are a few inches tall, thin them to the strongest plant every 12-18 inches.
Optimal Growing Conditions For Healthy Plants
Once planted in the right time, providing the right conditions ensures a spectacular show.
Sunlight And Location
Four o’clocks are flexible but perform optimally with ample sunlight.
- Full Sun: Promotes the most abundant flowering.
- Partial Shade: Plants will still bloom well, especially in hot afternoon shade in very warm climates.
- Consider their height: They can grow 2-3 feet tall and wide, so place them where they won’t shade out smaller plants.
Soil Preferences And Preparation
These plants are adaptable but have preferences for best growth.
- Soil Type: Well-draining soil is essential. They will not thrive in heavy, waterlogged clay.
- Soil pH: They tolerate a wide range, from slightly acidic to slightly alkaline (pH 6.0 to 7.5).
- Fertility: Moderately fertile soil is sufficient. Too much nitrogen can lead to lush leaves at the expense of flowers.
Watering And Fertilizing Guidelines
Proper water and nutrient management keeps plants healthy from seedling to frost.
- Watering: Water deeply once a week, more often during extreme heat or drought. Allow the soil to dry slightly between waterings. Established plants have some drought tolerance.
- Fertilizing: A light application of a balanced, slow-release fertilizer at planting time is often enough. Alternatively, you can use a liquid fertilizer every 4-6 weeks during the growing season. Avoid over-fertilizing.
Seasonal Care And Maintenance
A little ongoing care will maximize your flower production and keep plants looking their best.
Mulching And Weed Control
A layer of mulch around your four o’clocks provides multiple benefits.
- Apply 2-3 inches of organic mulch like shredded bark or straw.
- Mulch conserves soil moisture, suppresses weeds, and keeps soil temperatures more even.
- Keep mulch a few inches away from the plant stems to prevent rot.
Deadheading And Pruning
Four o’clocks are relatively low-maintenance but benefit from occasional attention.
- Deadheading (removing spent flowers) is not strictly necessary, as the plant will continue to produce blooms. However, it can improve the plant’s appearance.
- If plants become leggy in midsummer, you can cut them back by about one-third to encourage bushier growth and a fresh flush of flowers.
- They have few serious pest problems, though aphids or spider mites may occassionally appear. A strong spray of water usually controls them.
Overwintering Tubers In Cold Climates
In zones 7 and colder, four o’clocks will not survive winter outdoors. However, they form tuberous roots that you can save, similar to dahlias.
- After the first frost blackens the foliage, cut the stems back to about 4-6 inches above the ground.
- Carefully dig up the clump of tubers, trying not to damage them.
- Gently brush off excess soil and let the tubers dry in a cool, airy place for a day or two.
- Store them in a box filled with slightly moist peat moss, vermiculite, or wood shavings.
- Place the box in a cool, dark location where temperatures stay between 40°F and 50°F (4°C-10°C), like a basement or garage.
- Check periodically in winter to ensure they are not shriveling or rotting.
- Replant the tubers in the garden the following spring, after the soil has warmed.
Common Mistakes To Avoid
Being aware of these pitfalls will increase your chances of success.
- Planting Too Early: The number one mistake. Cold soil equals poor or no germination.
- Overwatering Seeds/Seedlings: This causes rot. Maintain moist, not wet, conditions.
- Skipping Hardening Off: Transplanting delicate indoor seedlings directly into the garden shocks them, stunting growth or causing death.
- Poor Spacing: Crowded plants compete for light and nutrients, leading to disease and fewer flowers.
- Over-fertilizing: Excess nitrogen creates all leaves and no blooms. Use fertilizer sparingly.
Frequently Asked Questions
Can I Plant Four O’Clock Seeds In The Fall?
In very warm climates (USDA zones 9-10) where frost is rare, you can plant seeds in early fall for late-season blooms. In most areas, fall planting is not recommended as seedlings will not survive winter.
How Long Do Four O’Clocks Take To Bloom From Seed?
When planted at the correct warm time, four o’clocks typically begin blooming about 60 to 90 days after germination. Plants started indoors will bloom sooner in the summer than those direct-sown.
Will Four O’Clocks Reseed Themselves?
Yes, they often readily self-sow. The seeds from dropped flowers can germinate the following spring if conditions are right. These volunteer seedlings can be thinned or transplanted. Be aware they may not come true to the parent plant’s color if you have multiple varieties.
What Is The Latest Date To Plant Four O’Clock Seeds?
For a reliable harvest of flowers, aim to get seeds in the ground no later than 10-12 weeks before your area’s first average fall frost date. This gives the plant enough time to mature and provide a good display. Later plantings may result in smaller plants with fewer blooms.
Can I Soak The Seeds Before Planting?
Yes, soaking four o’clock seeds for 12-24 hours in lukewarm water can help soften the hard seed coat and may speed up germination. It’s a helpful step but not strictly required if your soil is adequately warm and moist.