Liquid Seaweed: What It Does and How to Use It

August 29, 2026 · 2 min read

Liquid seaweed has been a gardener's favourite for generations, and for good reason. It's easy to use, safe on all plants year-round, and gives plants a noticeable boost through stressful times like transplanting, heat and drought.

What is liquid seaweed?

Daltons NZ Natural Liquid Seaweed is made from sustainably sourced Marlborough seaweed. It's a biostimulant: it contains natural plant growth compounds, vitamins and trace elements that encourage cell division and root formation.

It isn't a replacement for fertiliser. Think of fertiliser as the meal and seaweed as the tonic. Use both: a controlled-release fertiliser for the main nutrients, and seaweed to help plants make the most of them.

What it helps with

Stronger roots: encourages fast, healthy root development.
Less transplant shock: water in new plants and seedlings with seaweed to help them settle quickly.
Stress resilience: improves resistance to drought, heat, frost and disease.
Seeds and cuttings: soak seeds before sowing, or use as a rooting solution for cuttings.
Cut flowers: apply to flowering plants 2–3 days before cutting to extend vase life.

How to apply

Always dilute according to the directions on the label.

As a soil drench: apply with a watering can around the root zone. Best for new plantings, seedlings and containers.
As a foliar spray: apply to leaves with a low-pressure sprayer. Spray in the morning or evening, not in the heat of the day.
Through irrigation: it can be applied through irrigation systems for larger areas.

When to use it

At planting: water in every new plant, tree, hedge and seedling.
Through the growing season: regular applications through spring and summer keep vegetables, flowers and containers growing strongly.
Before and during heat or dry spells: helps plants cope with summer stress.
Before frosts: helps tender plants cope with cold snaps.
On lawns: great for new lawns and lawns recovering from summer stress or renovation.

Using seaweed with Daltons products

Water in seedlings planted into Daltons Garden Mix or Daltons Potting Mix to get them off to a fast start.
When planting trees and shrubs with Landscaper Planter Tabs, seaweed helps with establishment while the tabs supply long-term nutrition.
On newly sown lawns fed with Landscaper Pro New Grass & Renovations Fertiliser, seaweed encourages strong early root growth.

Quick answers

Can I use too much seaweed? Stick to the label rates. More isn't better, and very strong mixes are wasted.

Is it safe for natives and edibles? Yes. It's safe for use on all plants year-round.

Does it smell? It has a mild seaside smell that fades quickly after application.