How to feed your plants a healthy diet

By Sally Nex

Just like people, plants need food.

Also like people, a good diet is the foundation for health and happiness: and that means lush, leafy growth and a satisfyingly generous harvest for you to pick at the end of the season.

Making sure your plants have ready access to all the nutrients they need isn’t always as complicated as you might think. Some gardeners will come up with mind-bendingly detailed feeding routines to follow like a military campaign through the year, drawing from an armoury of chemicals in the garden shed. I prefer simpler, more planet-friendly ways to keep my veg happy.

In any case, feeding with artificial feeds is a stop-gap solution. It may produce quick results but it concentrates only on turbocharging plant growth, leaving you with a starved, nutrient depleted soil (which, ironically, means your plants will need more additional feeding as the years pass).

Instead, draw your plant feeds from nature’s larder: plant extracts and organic matter which, as it nourishes your plants, also enriches the soil till it teems with life, much of which is also helping your plants to grow better – so you get double the returns for half the effort.

Sounds good? It’s easy: all you have to do is remember three golden rules.

An annual mulch of garden compost or well-rotted manure is enough to feed your plants year-round

1: Feed the soil, not the plants

Plants feed mainly through the roots, absorbing nutrients from organic matter – mainly dead and decaying plants. The more organic matter your soil contains, the more nutrients your plants can access.

So mulch thickly every autumn, to a depth of 8-10cm, with home-made garden compost, municipal green waste or farmyard manure (checking first that it doesn’t come from pastures treated with herbicide).

You don’t need to add extra slow-release food too unless you’re starting a new veg patch from scratch and the soil is particularly poor, when a scattering of pelleted chicken manure or seaweed meal helps the first year’s crops.

Tomatoes are big, greedy plants which need extra feed once they start flowering

2: Only feed plants that need it

As long as your soil is in good heart there’s really no need to give additional feed to anything with its roots in the open garden: everything your plants need is already there in the ground.

So the only plants you actively need to feed are plants that aren’t in the ground, as they’re growing in pots, and plants growing in greenhouse borders with limited access to soil.

Most multipurpose composts run out of nutrients after about six weeks, so after that start adding a couple of capfuls of fast-acting liquid feed to the watering can once a fortnight to keep everything in containers and grow bags growing strongly.

Greenhouse borders hold more nutrients than a grow bag, but they’re supporting big, vigorous plants and a hefty tomato or cucumber can easily exhaust nutrient supplies. So once plants start flowering, add a potassium-rich tomato feed to the watering can once a week to make sure the soil has enough resources to support all those big long trusses of juicy fruit.

The range of feeds available can be bewildering – but all you really need is two

3: Feed the right food

We do best on three square meals a day, but plants are snackers, constantly taking in miniscule doses of minerals throughout the day. Each helps a different aspect of their growth: nitrogen for leafy growth, phosphorus to develop good sturdy roots, and potassium to encourage flowers to turn into fruit.

So it’s worth knowing what you’re feeding, and why. I use just two main types of feed:

  • Liquid seaweed for a good all-round tonic, keeping young seedlings, greenhouse plants and leafy container veg like lettuce and spinach healthy and growing strongly, with good root systems.

  • Comfrey feed: Once flowers appear on fruiting plants (tomatoes, chillies, aubergines and peppers) I I switch to potassium-rich comfrey feed to encourage maximum fruit production and bumper harvests. If you don’t have a comfrey patch, tomato feed does just as well.

Home made comfrey feed brewing in a bucket

How to make comfrey feed:

1: Harvest comfrey leaves by cutting just above soil level and pack them tightly into a bucket: the more you cram in, the richer your feed.

2: Cover with water and weight with a brick to hold everything in. Fit a lid as it gets a bit smelly! Then leave in an out-of-the-way spot for about six weeks.

3: Drain through an old sieve or piece of material to produce a brown liquid. Dilute about 1:4 with water, till it’s the colour of weak tea, then water onto your plants.

Sally Nex

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