This Is Your Sign to Fertilize Hungry Vegetables – When to Start a Regular Regime for the Best Harvests

And how to pick the best products to use, too

A close-up of a single light-purple eggplant flower on a plant in a glasshouse
(Image credit: Getty Images/JohnGollop)

Hungry vegetables, unsurprisingly, need regular feeding throughout the season. Topping the list of gluttons are tomatoes, peppers, cucumbers, zucchini, eggplant, squash, and pumpkins. Thankfully, it is quick and easy to get a good feeding regime going at the right time, and you’ll be rewarded with a bounty of harvests.

Once the plants start flowering, it's a signal to start feeding them weekly with a high-potassium fertilizer. This helps the plants to flower and fruit prolifically, rather than focus on developing excess leaves and stems. Well-fed plants will have all the nutrients to set and ripen lots of fruit.

If you are growing any of those crops outlined above, a high-potassium fertilizer, such as a tomato feed, becomes the best fertilizer for a vegetable garden throughout the summer. Personally, I always use a liquid feed and apply it weekly when watering plants. It is a simple regime to implement into your weekly gardening plans, and it is guaranteed to make a big difference to your harvests.

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When to Fertilize Vegetables After Planting

A gardener watering tomatoes in a greenhouse

(Image credit: Getty Images/Anna Mardo)

Understanding when to fertilize vegetables yields the best results – but the best feeding regimen varies by crop. Fertilizing a vegetable garden is not a one-size-fits-all approach. It is about understanding what each fertilizer does for plants, and when best to apply it.

It helps to add some fertilizer when you plant vegetables, either some compost or a slow-release, balanced product, to get the crop off to a good start when transplanting seedlings.

If you don’t feed at planting time, try to do it 3-4 weeks after. This window works when sowing seeds outdoors, as the crops benefit from nutrients once the seed germinates.

Light-feeding crops, such as roots, salad leaves, and leafy greens, often don’t need much more fertilizing unless they show signs of a lack of essential nutrients (such as slow growth or yellowing foliage).

On the other hand, heavy feeders want regular fertilizing throughout the season, often prompted by flowering.

Some hungry plants need additional fertilizer but don’t flower, such as brassicas and corn. These crops benefit from a single mid-season application of balanced or high-nitrogen feed.

However, hungry vegetables that flower and fruit don’t want lots of nitrogen at this stage of the season. They want a tailored, regular feeding regime, and that is what we focus on below.

Hungry Vegetables to Feed Once They Start Flowering

Zucchini and flower

(Image credit: Future)

There is a good list of hugely popular vegetables that benefit from extra feeding once they start flowering. If you adore growing veg, the chances are you will have a good number of these in your kitchen garden.

The bonus of having many of them in a space is that you can put aside a spare bit of time each week to mix a liquid feed and give those vegetables a much-needed boost.

The likes of tomatoes, peppers (both chili and bell peppers), cucumbers, zucchini, eggplant, squash (summer and winter squashes), pumpkins, and melons all sit on the list.

Once the plants start flowering, which can be 4-6 weeks after transplanting seedlings (the exact time will depend on location, weather, and variety), that is the sign to start implementing a regular feeding schedule.

Fertilize the plants every week or two as they continue to flower and fruit, until the last of the fruits are ripening.

If your hungry crops are growing in a vegetable container garden, I would definitely recommend feeding them weekly – that is a regimen I follow when growing hungry crops in pots, and it has worked fantastically growing tomatoes in pots.

The Best Feeds to Use

cucumber with flower

(Image credit: rbkomar / Moment / Getty Images)

As well as understanding when to fertilize vegetables, using the right feeds is fundamental. Get it right, and the plants will be vigorous and give you a wealth of harvests. Get it wrong, though, and you’ll be left disappointed with the yield.

Once the vegetables outlined above start flowering, the key is to use high potassium and phosphorus fertilizers. Using heavy-nitrogen fertilizers would be a mistake, as it encourages lots of lush leaves and stems rather than flowers and fruit.

The best fertilizers to use are tomato feeds. These products are high in potassium, which promotes flowers and helps to ripen fruits. The products also include all the other essential plant nutrients that help plants stay healthy and productive.

I would advise using a soluble product that you mix and apply when you water plants. These are quick and easy to use, providing a fast dose of nutrients to your vegetables.

I have always tried to pick one day a week to feed these hungry vegetables, so I kept a routine, and it became a part of my summer gardening norms.

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When you grow leafy greens, including lettuce, salad, arugula, and more, and brassicas, these vegetables need lots of nitrogen – the nutrient responsible for foliage and green growth. This guide to the best nitrogen fertilizer for vegetables reveals some of the top products to use to get the best harvests from these crops.

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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.