How to Grow Four 'O' Clocks Seeds

Grow Guide #2352
Family: Nyctaginaceae
Binomial name: Mirabilis sp.
Life Cycle: Perennial (grown as an annual in cool climates)

This 'How to Grow' guide details everything a home gardener needs to know to plant, grow and care for Four 'O' Clocks (Mirabilis sp.).

When to Sow Four 'o' clocks Seeds

Use the table below to identify the best time of year to sow four 'o' clocks seeds in your climate.

  JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Cool
Temperate
Sub-Tropical
Tropical
Arid

Preparation

Four 'o' clocks plants are best grown in full sun. Choose a location that will receive at least 6 hours of full sun each day.

Four 'o' clocks plants are perennial, meaning they live for several years. Choose a permanent position where plants can grow undisturbed by regular digging.

Four 'o' clocks plants need a well drained soil enriched with plenty of organic matter. Prepare soil by weeding it thoroughly, digging it over to loosen it and adding aged animal manure or compost. Keep the area free of weeds until planting. Learn more about preparing soil for planting here.

Four 'o' clocks plants can be grown in containers. If possible choose a variety that’s recommended for container growing. Use a good quality potting mix and make sure your container is large enough for mature plants; a minimum of 10 litres is recommended for Four 'O' Clocks. During the growing season, keep in mind that container grown plants may need additional fertiliser to encourage healthy growth.

How to Sow Four 'o' clocks Seeds

Four 'o' clocks seeds do not require any treatment (eg soaking, stratification) before sowing.

Four 'o' clocks seeds can be sown directly into the garden OR seedlings can be raised in trays or other containers and transplanted to the garden once established.

Sow Direct

  1. Sow seeds directly in the garden 20mm deep and 50cm apart.
  2. Keep soil moist but never wet or dry.
  3. Seeds should germinate in around 7-14 days at a soil temperature of 20-22°C.
  4. Young seedlings will need protection from pests, pets and weather until they are established.

Raise Seedlings

  1. Fill trays, punnets or jiffy pots with a good quality seed-raising mix, or use soil starter pellets.
  2. Sow seeds 20mm deep.
  3. Keep soil moist but never wet or dry.
  4. Seeds should germinate in around 7-14 days at a soil temperature of 20-22°C.
  5. Transplant seedlings to the garden once they have their first true leaves and are large enough to handle (usually 5-10cm tall).
  6. Plant out, spacing plants 50cm apart.

Four 'o' clocks is a tender crop that’s sensitive to frost. Do not transplant seedlings or sow seeds outside until all danger of frost has passed.

Optional: In cool climates four 'o' clocks seeds can be sown indoors 6 weeks before the last expected frost. Grow them in a warm position with plenty of natural light.

How to Grow Four 'o' clocks

Four 'o' clocks plants may need watering during the growing season. Water when the soil is dry about 5cm below the surface (test this by scratching away a little soil with your finger). Water deeply in the early morning or late afternoon. Avoid watering the leaves of plants to avoid fungal diseases. Learn more about watering here.

If soil was well prepared no extra fertiliser should be necessary. In poor soil or to give your plants an extra boost, application of a high-potassium fertiliser or one formulated for flowering plants can be beneficial:

  • Apply slow release fertiliser at the recommended rate when transplanting or when seedlings are 5-10cm tall.
  • Apply liquid fertiliser at the recommended rate and frequency while plants are fruiting or flowering.

Four 'o' clocks plants may need to be supported as they grow. Depending on the expected size and height of the plant, use a stake, bamboo cane, trellis or string lines to support plants. Make sure you have the support in place when you sow seed or transplant seedlings to avoid disturbing the plant's roots later.

Four 'o' clocks plants should flower in approximately 75-85 days.

Deadhead four 'o' clocks flowers regularly during the growing season. Using sharp secateurs or snips cut fading or dead flowers off just above a set of leaves. Removing old flowers regularly will encourage plants to produce more flowers. Learn more about deadheading flowering plants here.

When plants have finished flowering prune them back to neaten them and encourage strong new growth. Using sharp secateurs or snips, cut individual stems just above a set of lower leaves.

Common Problems when Growing Four 'O' Clocks

Like all plants, four 'o' clocks is susceptible to some pests, diseases and other problems. Below is a list of the most common problems gardeners encounter when growing four 'o' clocks plants:

  • Aphids
    Aphids are small (2-4mm long) sap-sucking insects that congregate on the new shoots or the undersides of leaves. They can cause leaves to wilt or become discoloured, and also excrete honeydew which can attract ants and other insect pests. To manage aphids, remove them by spraying with a garden hose, apply a soap or alcohol spray, or encourage predatory insects to your garden. Read more about aphids here.
  • Slugs and Snails
    Slugs and snails are molluscs that feed on tender leaves and shoots, mostly at night, leaving slimy trails behind them. Control them by removing their hiding places, keeping free range poultry, collecting them by torchlight or by placing traps. Read more about slugs and snails here.
  • Rust fungus
    Rust (Puccinia sp.) is a fungal disease that causes brown to orange raised spots or patches to appear on foliage. Fungal spores are spread by wind or water to neighbouring plants, especially in temperatures of 10-20C and when humidity is high. To manage rust, space plants to avoid overcrowding, grow them in the recommended amount of light (eg full sun), do not over fertilise crops, remove dead plants and practice crop rotation. Read more about rust fungus here.

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