Growing veg in containers: keep it cropping

by Kate Bradbury

As container-grown fruit and veg start to crop, it's important keep your eye on the ball to ensure they stay productive.

Runner beans in a bowlAs container-grown fruit and veg start to crop, it's important keep your eye on the ball to ensure they stay productive. I've just harvested a small batch of French beans from my late container sowing as part of the Grow Yourself Healthy campaign, and I'm looking forward to several more over the next few weeks.

There are many ways to keep fruiting crops (beans, peas, tomatoes, chillies) productive. The obvious one is to keep feeding them. These plants need extra nutrients once they've finished flowering, to ensure they have enough energy to grow the chillies, tomatoes or beans we're growing them for. This is especially pertinent when growing them in containers, as there is only a finite amount of nutrients in the compost. Once this is used up, foliage can quickly turn yellow and the yield will decline.

A weekly liquid feed of a high-potash fertiliser like tomato feed will keep plants healthy and productive. Potash, or potassium, promotes flower and fruit production and ensures strong growth and disease resistance. Potassium is naturally found in wood ash and deep-rooted plants like comfrey. I grow comfrey in the garden and use it to make a liquid feed for my fruiting crops.

It's also important not to let leafy crops, like lettuce, or root crops like beetroot, seed. Again, the plant will focus its energy on seed production at the expense of the leaf, or root you are growing it for. Remove flowers as soon as you see them, water well. Moving the pot to a shadier spot can also help (sun can stress the plants, causing them to seed prematurely).

Container-grown crops also need watering more than those growing in the ground, as much as once or twice a day in hot weather.

Just as sweet peas and other ornamental plants need deadheading to keep them producing flowers, fruiting crops need regular harvesting to stimulate the production of flowers and fruit. If you let beans, for example, mature on the plant, flowering and fruiting will stop. Harvest young, tender beans for eating and, if you've missed a few that are big and stringy, remove these too to keep the crop coming. There will be plenty of time for saving seed later.

Keep containers weed free, as weeds can compete with crops for water and nutrients and block light to developing fruit. Remove dead or dying foliage and ensure pots aren't placed too closely together. Dead foliage can lead to the onset of disease, while closely growing plants prevent airflow between them, providing the perfect conditions for diseases and infestations of blackfly and red spider mite.

Which crops are you growing in containers? Have you got any tips to share?

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Gardeners' World Web User 05/08/2011 at 21:12

Due to extremely chalky soil I am growing all of my veg in containers. This is my first time growing veg, done cucumbers and sweet peppers in containers and salad leaves in a basket. Working well so far, cucumbers will be ready in a few weeks and peppers just flowering. Also started to use spent coffee beans from local shop.

Gardeners' World Web User 05/08/2011 at 21:54

This must be why my container-planted pink fir apple potatoes haven't done very well. I only fed them twice and now they have gone yellow and keeled over without even flowering. A woeful peformance (from me I mean, not the potatoes). They suffered massive slug and snail attack too: that does seem to be a disadvantage of containers.

Gardeners' World Web User 06/08/2011 at 08:57

I had the same trouble last year with pink fir apple potatoes out in the veg,. garden, Mandy, and blamed poor seed as all my other early potatoes were fine. Vine weevils love container grown plants to lay their eggs in and the grubs eat the roots so you have to be very vigilant. My best success is growing tomatoes in big pots - they do escape blight that way should it be a good year for potato blight.

Gardeners' World Web User 06/08/2011 at 21:50

Hi Marion, as usual you're a mine of info! Thanks.

Gardeners' World Web User 06/08/2011 at 22:48

Can someone tell me if carrot leaves are edible please? I have a pot full of leaves but there is not enough room for the carrots to grow so I need to thin them out and am loath to throw them onto the compost, if I can eat them...thanx to anyone who can reply.

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