Watercress Herb Seeds

Watercress is a hardy perennial leafy herb grown for its tender stems and peppery green leaves. It prefers cool conditions and a consistently moist to saturated root zone.

Quick Start

• Sowing season: Favour cool to mild conditions
• Sowing depth: Surface sow to approximately 1–2mm
• Germination: approximately 7–14 days
• Germination temperature: approximately 10–18°C
• Plant spacing: approximately 15–20cm
• Position: Full sun to partial shade
• Moisture: Consistently moist to saturated
• Mature height: approximately 15–30cm
• First useful harvest: approximately 50–60 days
• Life cycle: Hardy perennial

When to Sow

General Australian guidance:

• Cool climates: spring through early autumn
• Temperate climates: autumn and spring; winter growing may also be possible in mild areas
• Subtropical climates: autumn through early spring
• Tropical climates: favour the coolest months
• Hot and arid climates: autumn through spring

Avoid establishing young plants during periods of extreme heat where possible.

Sowing

Watercress can be raised in trays or sown directly into a container or bed that can be kept consistently moist.

1. Fill trays or pots with fine seed-raising mix.
2. Thoroughly moisten the growing medium.
3. Scatter the fine seeds thinly over the surface.
4. Press gently into contact with the moist mix.
5. Leave uncovered or cover only very lightly, to approximately 1–2mm.
6. Mist gently or bottom water so the seed is not displaced.
7. Keep the growing medium continuously moist.
8. Provide good light.
9. Transplant once seedlings are established and strong enough to handle.

Germination

Expect germination in approximately:

7–14 days

Aim for approximately:

10–18°C

Do not allow the seed surface to dry during germination.

Position & Spacing

Grow in:

Full sun to partial shade

Allow approximately:

15–20cm between plants

In cool conditions, Watercress can tolerate more direct sun. In hot weather, morning sun with afternoon shade can help reduce heat stress.

Watering & Moisture

Reliable moisture is the most important requirement.

Keep the root zone:

Consistently moist to saturated

Unlike Thyme, Sage or Rosemary, Watercress should not be allowed to dry between waterings.

For garden-grown plants:

• water before the soil begins drying;
• maintain consistent moisture through warm or windy conditions;
• mulch where useful to reduce evaporation.

For containers:

• use a self-watering pot or place the pot in a shallow reservoir;
• maintain a few centimetres of clean water where suitable;
• keep the foliage above the water;
• top up as water is absorbed or evaporates; and
• refresh standing water regularly.

Do not allow reservoir water to become stagnant, foul smelling or contaminated with organic debris.

Growing Watercress in Pots

Use a container approximately:

20–30cm wide or larger

with:

• quality potting mix;
• drainage holes;
• full sun to partial shade; and
• a shallow saucer, tray or outer reservoir.

Container growing is one of the easiest ways to maintain the consistently wet root conditions Watercress prefers.

Growing in a Moist Garden Bed

Choose an area that:

• naturally retains moisture;
• can be watered reliably;
• receives sun or partial shade; and
• does not dry rapidly.

Do not treat Watercress like a conventional dry herb bed.

Feeding

Watercress grows quickly where moisture and nutrients are readily available.

In fertile garden soil, heavy feeding is usually unnecessary.

Container-grown plants may benefit from occasional liquid feeding during active growth according to the fertiliser manufacturer's directions.

Harvesting

A useful harvest generally begins from approximately:

50–60 days after sowing

Light harvesting may begin earlier where plants establish quickly.

Cut healthy young leaves and tender stems above lower growing points, leaving enough foliage for regrowth.

Regular harvesting helps maintain tender, leafy growth.

Managing Hot Weather

During hot weather:

• provide afternoon shade;
• check moisture frequently;
• keep the root zone continuously wet;
• avoid containers becoming excessively hot; and
• remove stressed or damaged foliage.

In tropical and subtropical areas, Watercress is generally easiest to grow during the cooler part of the year.

Food Safety

Because Watercress is often eaten raw, clean growing conditions are important.

For home-grown edible Watercress:

• use clean containers and gardening equipment;
• use clean, drinking-quality water where practical;
• avoid natural waterways of uncertain water quality;
• avoid water exposed to livestock, animal waste, sewage or contaminated runoff;
• refresh standing container water regularly;
• refrigerate harvested leaves promptly;
• wash thoroughly under clean running water before use; and
• discard leaves that are slimy