Why Vegetables Aren’t Growing (and How to Fix It)

It's disheartening when your vegetables come up, then just sit there. The plants aren't dead, but weeks go by and they barely get any bigger. Happily, a stalled crop is rarely a mystery. There are only a few things a plant needs, and finding the one that's missing is usually quick.

This guide helps you narrow it down, then points you to more detailed help for each crop.

Quick answer

Vegetables that aren't growing are usually short of one of the basics: warmth, light, water, food or space. The most common causes are cold weather or sowing too early, too much shade, soil that's too dry or too wet, poor or compacted soil, overcrowding, and pests such as slugs. Check each of these in turn. Most plants pick up within a couple of weeks once the problem is put right.

Start here: what are you seeing?

It's too cold

Temperature controls how fast plants grow. In cold soil and chilly air, even healthy plants barely grow, and tender crops such as tomatoes, courgettes, beans and squash can stop growing completely.

What to do: be patient in a cold spring, as growth usually speeds up once the weather warms. Don't rush tender crops outside before the last frost. Cover young plants with fleece or cloches on cold nights, and cover the soil for a week or two before sowing early crops to warm it up. See when to plant vegetables in the UK for timings.

Not enough light

Vegetables need sunlight to grow. In shade, they grow slowly, look pale and stretched, and fruiting crops produce few flowers. As a rule of thumb, aim for six hours or more of direct sun for most crops.

What to do: move pots into the brightest spot you have. In beds, cut back overhanging branches if you can. Next time, save shady areas for leafy crops that cope better with less sun, such as lettuce, spinach and chard, and give tomatoes, beans and squash the sunniest positions.

Too little water

Plants stop growing quickly in dry ground, and pots, raised beds and sandy soil dry out fastest. Without water, roots can't take up nutrients, so growth grinds to a halt.

What to do: push a finger into the soil. If it's dry a few centimetres down, give a thorough soak rather than a light sprinkle. Mulch around plants to keep the moisture in. See signs of underwatering and how often to water a vegetable garden.

Too much water

Waterlogged soil is just as bad. Roots need air as well as water, and in soggy ground they can't breathe, so plants look yellow, limp and stunted even though they're wet.

What to do: let the soil dry out a little before watering again, and make sure pots have drainage holes. On heavy clay that stays wet, raised beds and plenty of organic matter help. See signs of overwatering and how to fix waterlogged soil.

Poor or hungry soil

Vegetables need nutrients to grow, and thin, tired soil can't supply enough. Pale green or yellowing leaves and small plants are common signs. Plants in pots run out of food even faster, as the compost only holds nutrients for a few weeks.

What to do: before you next sow or plant, fork a thick layer of homemade compost or rotted manure into the top of the bed. For plants already growing, a liquid feed gives a quick boost. See best soil for vegetable gardening in the UK and how often to feed vegetable plants.

Compacted soil

Soil that's been walked on or has set hard is difficult for roots to push through. Water also runs off the surface instead of soaking in. Root crops such as carrots and parsnips suffer most.

What to do: avoid standing on growing areas, especially when the soil is wet. Loosen the surface gently with a fork around established plants, and add organic matter each year. See why soil becomes compacted.

Plants are too crowded

Plants packed too closely compete for light, water and food, and they all end up small. This often happens when seedlings aren't thinned.

What to do: thin seedlings to the spacing on the seed packet, even though it feels wasteful. The plants that remain will grow much faster. Next time, sow more thinly.

Pests

Slugs and snails can eat young plants as fast as they grow. Pests at the roots, such as cabbage root fly or carrot fly, can stunt plants without any obvious damage above ground.

What to do: check plants for slugs after dark on damp evenings, and protect young plants until they're established. If a plant suddenly stops growing for no obvious reason, gently check the roots. See slugs eating vegetable plants and why vegetables get holes in leaves.

Transplant shock

Plants moved from pots into the ground often stop growing for a week or so while their roots settle. Plants that weren't hardened off, or were left too long in small pots, can take much longer to recover.

What to do: harden plants off over a week or two before planting them out. Water them well before and after planting, and plant on a dull day or in the evening if you can. Our hardening off guide walks you through it.

Wrong time of year

Some crops simply won't grow well outside their season. Lettuce and spinach struggle and bolt in hot, dry summers, while tomatoes and squash stop growing in cool weather. Garlic needs a winter chill before it will split into cloves, and onions only start swelling once summer days are long enough.

What to do: check the sowing window for each crop and sow at the right time. See why plants bolt if your crops are running to seed.

Common questions

Why are my vegetable plants not growing?
Usually because they're short of warmth, light, water, food or space. Cold weather, shade, dry or waterlogged soil, poor soil, overcrowding and slugs are the most common causes.

Why are my vegetables growing so slowly?
Cool weather is the most likely reason in spring and autumn. In summer, dry soil and hungry soil are more common. Plants in pots may also have run out of nutrients and need feeding.

How can I make my vegetables grow faster?
Give them a sunny spot, rich soil with plenty of compost, steady watering and enough space. Sowing at the right time for each crop makes a big difference too.

Why are my vegetable plants small and yellow?
Pale, stunted plants are often short of nutrients, or sitting in waterlogged soil. Check the drainage first, then give a liquid feed if the soil drains well.

 
laura tennant