All plants need nutrients to grow. For vegetable plants, it’s even more important, because they need nutrients to produce a good yield.
So if you want a good yield, it’s vital that you provide your plants with the right nutrients at the right time.
But what do you feed your veggie plants? And how do you feed them, and with what?
To help you with that, we have pulled together the most frequently asked questions about feeding vegetable plants in the UK and answered them.
What Nutrients Do Vegetable Plants Need?
This will depend on the growth stage your plants are in, because they will need different nutrients at different times. But these are the main nutrients plants need to grow strong and healthy:
- Nitrogen
- Potassium
- Calcium
- Magnesium
- Phosphorus
- Iron
Nitrogen is an important nutrient for the growth of foliage. That’s because nitrogen regulates photosynthesis, which is how plants turn sunlight into food. (Guan et al., 2025) So seedlings and young plants will need quite a lot of it.
Once your plants have started to crop, you want them to focus on the fruit rather than the foliage. This means you want to feed them a fertiliser that is high in potassium.
Potash, as it’s also called in gardening circles, helps with enzyme activation and protein synthesis, both of which are vital for a good yield. But potassium can also reduce the effects of droughts. (Zain et Ismail, 2015)
The other nutrients are just as important for the growth of plants. So you want a fertiliser that contains as many nutrients as possible. But paying attention to nitrogen and potassium in particular.
How Can I Feed My Vegetable Plants?
Plants take up nutrients through their roots. So they have to be in the soil to be available to your vegetable plants. There are three ways to enrich your soil with important food for your plants:
- Dig organic matter into your soil
- Add a layer of organic matter or mulch to your soil
- Feed your plants with liquid fertiliser
If you use the first two methods, then it becomes less necessary to feed your plants with a liquid feed. That’s because the soil will already be rich in nutrients before you put your plants in.
The best time to dig in organic matter is autumn, when the cropping season has finished. Then in early spring, you can add a layer of mulch, which will release more nutrients into the soil as it breaks down.
But it will also suppress weeds, which is great news for any busy gardener.
Is Homemade Fertiliser Better Than Shop-Bought Fertiliser?
The short answer is yes. Most liquid feeds you can buy are made with synthetic nutrients, as they are cheaper and easier to get.
One problem with synthetic fertilisers is that they aren’t as easily absorbed by plants as natural ones. This can lead to a surplus of nutrients like nitrogen, which can lead to biodiversity loss in the soil ecosystem. (Galloway et al., 2003)
The use of synthetic fertilisers can disturb the microbiome of the soil, which is the group of microorganisms that live in the soil. They include bacteria, fungi, and viruses, among others.
These microbes are vital for the health of plants, as they perform many vital functions. One of them is making nutrients in the soil available for plants to absorb. (Compant et al., 2019)
So to keep the soil microbiome happy, refrain from using synthetic liquid fertilisers.
How Often Should I Use A Liquid Fertiliser?
As we have said, this will depend on how good your soil is. If you have mixed in organic matter or well-rotted manure in the autumn or winter, then you will need to feed your plants less.
Generally, it is said that plants like tomatoes, potatoes, cucumbers, and courgettes, which are all hungry plants, will need feeding 1-2 times a week once they start producing fruit.
Best with a high-potash fertiliser, as this will encourage the production of fruits.
Potato plants will also need a lot of nitrogen while they are growing, as they produce potatoes from their stems, rather than roots.
So, if you feed them with a nitrogen-high fertiliser, such as nettle liquid fertiliser while they are growing, you will get bigger, stronger plants and a higher yield.
Again, 1-2 times a week will ensure that your potato plants grow well.
The same is true for leafy crops such as lettuce, cabbages, spinach, or kale. They need nitrogen to grow, so feed them the right fertiliser 1-2 times a week.
Because we add a thick layer of mulch to our vegetable beds (we have a no-dig garden, so we don’t dig in anything), I only use liquid feed every other week, once my plants have started to produce fruit.
Can I Make My Own Liquid Fertilisers?
Given that feeding vegetable plants in the UK is important, but synthetic fertilisers aren’t so good for the soil, this is a good question.
The good news is, the answer is yes. And it’s very easy and cheap to make them, too. You probably have all you need already in your garden. All you need is:
- A bucket with a lid
- Water – ideally collected rainwater
- A bottle to store the liquid feed
- Organic material
In terms of organic material, you have a wide range of choices:
- Weeds
- Leaves – although personally I would use them to make leaf mulch
- Seaweed
- Compost
- Crass clippings
- Well-rotted manure
- Coffee grounds
- Vegetable kitchen scraps
For most of these materials, the method of making natural liquid feed is the same:
- Fill a bucket half full with your chosen organic material
- Top up with rainwater until the bucket is full
- Put a lid on and leave anywhere from a few days to 6 weeks, depending on what you use
- Strain into a bottle
- Dilute with rainwater and water plants from underneath as required
If you are now keen on making your own liquid feed, read our article that will give you 10 recipes for homemade liquid fertilisers.
What Is The Best Homemade Fertiliser For Vegetables?
Any homemade fertilisers will be great for your vegetables.
But if you want a liquid plant food that is especially high in potassium, which will help plants grow flowers and fruits, then a banana liquid fertiliser is the best.
Because banana peels contain a high proportion of potassium, or potash, which means your tomatoes will grow plentiful and juicy.
If you need a homemade fertiliser that is high in nitrogen, then use a nettle liquid fertiliser. It will help your plants grow healthy foliage.
When Should I Be Feeding Vegetable Plants In The UK?
When we talk about feeding plants, we mean putting the right nutrients into the soil so that the plants can absorb them. So the feeding doesn’t necessarily only happen once the plants are in the ground.
To ensure that the soil in our veggie beds is rich in nutrients in late spring/early summer for our plants to thrive, we follow this routine:
1. Winter: Add Homemade Compost
Once all our vegetable plants have finished cropping, we cut their stems just above soil level. As we have a no-dig garden, we don’t pull them out. This would disturb the microbial ecosystem in the soil, which is vital for healthy soil and plants.
Then we weed the beds and add a thin layer of homemade compost. A thin layer is enough, because we will add mulch later in the year.
Besides, our compost is very nutrient-rich, as it’s mostly made from vegetable kitchen scraps, of which we have loads.
Over winter, the nutrients will seep into the soil, together with food for the microorganisms that live in the soil.
2. Early Spring: Add Leaf Mulch
Once the days get a bit warmer, in early April, we add a thick layer of homemade leaf mulch to the beds. By now, the compost will have released many nutrients into the soil.
The mulch will fulfill two functions: first, it will release more nutrients into the soil as it continues to decompose. Secondly, it will suppress weeds, so we have less weeding to do in spring.
We tend to weed the beds again if necessary, but if you can afford to put a very thick layer of mulch (at least 2inch/5cm) on, small annual weeds will die off as the mulch will starve them of light.
3. Feed Seedlings After Germination
I like to give my plants the best start, so when I repot them into bigger pots after they have germinated, I feed them. I usually use the liquid fertiliser that we get from our wormery, as it’s full of vital nutrients.
If you don’t have a wormery, you can use any homemade liquid fertiliser. Nettles are full of nitrogen, which is just what seedlings need, so make one from this very useful plant, which will be plentiful in spring.
4. Feed Plants Once They Start Fruiting
Because we enrich our soil and feed the seedlings in the pots, I don’t feed them often once they are fully grown. However, when they start to produce fruit, I will to ensure they give a good yield.
My go-to liquid fertiliser is the liquid feed we get from our wormery, as it’s the best.
Many gardeners say to feed your plants at least once a week once they start to grow fruit, but I find that it’s not necessary, because I have prepared the soil so well.
As a result, I only feed them once every two to three weeks.
So here you go, all your questions about feeding vegetable plants in the UK answered. Happy Growing!
