How to make tomato leaf spray?

Making tomato leaf fertiliser is an eco-friendly and effective way to enrich your garden. Used as a natural fertiliser or pest repellent, tomato leaf fertiliser is part of a sustainable gardening approach, promoting plant health without resorting to chemicals. This tutorial will guide you through simple steps to prepare your own tomato leaf fertiliser, sharing tips and tricks to maximise its effectiveness. Whether you're a novice or experienced gardener, discover how to turn tomato plant waste into a valuable garden booster.

What is tomato leaf fertiliser?

While nettle fertiliser is well-known among gardeners, tomato leaf fertiliser is less discussed—yet equally useful in the garden.

Tomato leaf fertiliser is a decoction made from the green parts of healthy tomato plants. When pruning your tomato plants, collect as many suckers as possible (stems growing in the leaf axils), which will be used to prepare the fertiliser.

© anabela2 - Inaturalist

Suckers are the secondary stems of tomato plants that don’t bear fruit but can be fermented in water (preferably rainwater) to create a fertilising, repellent, and insecticidal decoction. Indeed, suckers are packed with active compounds perfect for making fertiliser.

Tomato leaf fertiliser recipe

Ideally, you’ll mainly use suckers to make tomato leaf fertiliser. However, you can also use leaves from your plants. In this case, only use healthy leaves with a vibrant green colour, preferably young ones.

Healthy tomato leaves - © Alexis Orion - Inaturalist

Key point: whether using suckers or leaves, ensure your base ingredients are completely disease-free. Otherwise, your fertiliser may spread diseases to other plants when applied.

Ingredients for tomato leaf fertiliser

• 1 kg of tomato leaves or suckers,
• 10 litres of rainwater.

Equipment

• 1 sharp knife,
• 1 large wooden or plastic* bucket with a lid,
• 1 watering can.

*Avoid metal containers due to potential oxidation—this applies to all types of plant fertilisers.

Preparing tomato leaf fertiliser

1. Start by chopping the leaves and suckers with a knife.
2. Place the plant material in the bucket.
3. Pour rainwater over the leaves and suckers.
4. Cover the bucket as tightly as possible.
5. Let it steep for about 4 days (duration may vary depending on temperature).
6. Stir once daily and monitor the fermentation bubbles. When they disappear, your fertiliser is ready.
7. Strain the mixture and pour the liquid into opaque containers.
8. Store the fertiliser in a cool place like a cellar or garage.

When and how to use tomato leaf fertiliser?

There are three ways to use homemade tomato leaf fertiliser: as a fertiliser, repellent, or insecticide.

As a fertiliser

Mix 1 litre of fertiliser with 3 litres of rainwater in a watering can. Every two weeks, use this mixture to water the base of your plants. This fertiliser works best for certain fruits and vegetables, particularly tomatoes, cabbages, and squashes. While effective, you may not use it long-term due to the large quantity of suckers needed to make just one litre.

As a repellent and insecticide

Naturally repellent, tomato leaf fertiliser is ideal for deterring pests like carrot flies and cabbage white butterflies. It can also treat existing infestations, such as aphids.

Use undiluted fertiliser in a spray bottle, applying it directly to the foliage at the first sign of pests. Reapply every 2–3 days as long as the threat persists.