If Your Tomato Plants Are Still Small and Not Flowering, This 1 Natural Feed Will Help Them Put on Growth Fast

Act fast, as the window to use it may be closing quickly

Red tomatoes growing on plants in a greenhouse
(Image credit: Getty Images/iStockphoto/fotokostic)

Do you see friends and growers on social media with tomato plants well ahead of yours? Are you concerned yours are being left behind? If so, there is one product you can use to spark new life into your plants. Discover how using fish emulsion on tomato plants gives them a real boost during their early growth.

Fish emulsion, or fish fertilizer, is a product made from the by-products of the fishing industry. It is not glamorous, made from the likes of ground-up carcasses, bones, and scales, but it is high in nitrogen and encourages vital, strong growth when used at the right time.

If you are growing tomatoes and your plants are still small, fish emulsion can give them a much-needed dose of nutrients. However, you only want to use it on young plants and not once they start flowering. The window to use it is closing and may be shut for some gardeners, but if your tomato plants need a much-needed boost, it could be the solution you’re looking for.

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This Alaska Fish Fertilizer from Amazon is certified for organic gardening and comes in concentrated form to mix with water and feed your tomato plants.

Why Use Fish Emulsion on Tomato Plants

Young tomato plants growing in containers in a greenhouse

(Image credit: Getty Images/Guido Mieth)

Understanding how to fertilize tomatoes ensures you use any products at the right time, for the desired results – healthy plants and bumper crops. When it comes to using fish emulsion on tomato plants, there is a right and wrong time to use it. It boils down to what the fertilizer does for the plants.

Fish emulsion (like this liquid salmon feed, available on Amazon) is primarily rich in nitrogen (it also includes phosphorus, potassium, and many other trace elements), and it releases it quickly, encouraging the development of stems and foliage.

If your plants are a bit stunted or behind where you’d ideally like them this month, an application of fish emulsion can be a vital pick-me-up to get them back on track. It makes a perfect organic feed for the early stages of growth; you want strong stems and leaves at this time.

However, don’t use fish emulsion once the plants have started flowering. At this stage, you use a tomato feed with more phosphorus and potassium. Giving tomato plants too much nitrogen will encourage more leaves and stems, rather than flowers and fruit.

How to Use Fish Emulsion on Tomato Plants

Young tomato plants growing in tomato cages

(Image credit: Getty/jahall4)

Fish emulsion is a simple product to use, but there are a few recommendations to follow and fertilizing mistakes to avoid when using it:

  • Fish emulsion must be applied to damp soil to avoid shocking the roots. Before using the product, water the tomato plants lightly to ensure the soil is moist and the plants aren’t badly affected by the feed.
  • Always use the product at the recommended rate. It is a concentrated liquid fertilizer, and each product will state the dilution rates. Don’t be tempted to add a bit more, as too much will over-fertilize the plants and potentially burn their roots.
  • The best results will come from a set routine. Mix the product with water and feed plants every 2-3 weeks from transplanting tomato seedlings until they start flowering.
  • Apply the feed to the soil, rather than the tomato plant’s leaves. Watering the soil ensures no product is wasted and it efficiently reaches the roots.
  • The product does have a strong odor, and watering the soil limits the spread and also the likelihood of attracting pests. If you worry about the smell, rest assured it disappears within a day or two of using the product.
  • As mentioned above, stop using fish emulsion on tomato plants once the first flowers appear. Switch to a tomato feed, which includes organic solutions such as seaweed extract, comfrey feed, or a certified organic tomato fertilizer.

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It is not just tomatoes that can benefit from fish emulsion. Its high nitrogen levels make it a perfect solution for any seedlings and young plants – both flowers and vegetables – that need a punch of essential nutrients in the early stages. It offers a strong, natural way to add nitrogen to your soil, along with adding homemade compost, manure, or blood meal, like this organic blood meal, available at Burpee.

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Drew Swainston
Content Editor

Drew has worked as a writer since 2008 and was also a professional gardener for many years. As a trained horticulturist, he worked in prestigious historic gardens, including Hanbury Hall and the world-famous Hidcote Manor Garden. He also spent time as a specialist kitchen gardener at Soho Farmhouse and Netherby Hall, where he grew vegetables, fruit, herbs, and cut flowers for restaurants. Drew has written for numerous print and online publications and is an allotment holder and garden blogger. He is shortlisted for the Digital Gardening Writer of the Year at the 2025 Garden Media Guild Awards.