How to grow great herbs – 10 expert tips for outdoor success

It all begins with a sorry-looking basil plant from your local supermarket. No matter how much water you give the dinner-table staple, it often shrivels within days.

Even if you’ve mastered the art of windowsill herbs – making that leap from kitchen to garden can be tricky. But our tips for growing herbs outdoors will help you make like Monty Don and be harvesting for meals and tipples in no time at all.

Growing herbs outside isn’t the easiest garden task. Though many thrive in poor soil, our climate is less than clement compared to our favourite aromatics’ native lands. Rosemary and thyme, for example, thrive in the Mediterranean's scorched soil, while basil grows wild in the sultry landscapes of India and tropical Africa.

That said, there are still plenty of ways you can give herbs a helping hand.

1. Give your seedlings space to grow

Though it’s tempting to try to salvage your supermarket herbs, you can also grow herbs outdoors from seed. And there’s a handy hack for safe handling of these delicate young plants that’ll recycle household waste, too.

“Try the toilet-roll tube trick to make transferring seedlings easy,” says Kate Lindley, product manager for Baby Bio. “Simply snip toilet roll tubes in half, line them up in a tray filled with compost and sow your seeds. We recommend sprinkling two to five seeds per tube to ensure they have plenty of space to grow.

“Once the seedlings are ready to be moved to their own containers, you can transfer the entire tube to the pot without disturbing your seedling, and it will eventually decompose.”

2. Harden off your herbs

One major tip for growing herbs outdoors is to acclimatise young plants first. By popping new herbs in a sheltered spot outside, they can gradually get used to the sun, wind and rain.

“This allows the herbs to gradually get used to the change in temperatures and become hardened to weather conditions, making your chances of growing a flourishing and long-lasting plant much higher,” explains Daniel Carruthers, the ‘grow your own’ expert at Cultivar Greenhouses.

“To harden off, take them outside during the warmth of the day and place in a partially shaded area. At night, bring them back inside. Gradually, over the space of a few weeks, put your herbs into a sunnier, more open spot during the day and, eventually, you will be able to plant your newly hardened plants outside for good.”

At night, bring your herbs indoors – whether that’s a greenhouse or your home. It’s worth knowing basil might not survive at all in colder conditions, but we’ll get onto that later.

3. Use horticultural grit generously

Herbs such as rosemary and thyme can be found in their native home clinging to rock faces. But loving such poor soil conditions doesn’t mean you can assume they’ll thrive without water. Their roots have evolved to seek out moisture, so replicating these natural conditions with free drainage will help young plants mature and thrive.

“Do not fall into the trap of forgetting to water them regularly or letting them get pot-bound,” Monty Don explains on his blog.

“Any plant that has evolved to live in drought will have roots that want to range freely to seek out moisture. If you are planting herbs in a container, mix general purpose peat-free compost with at least an equal measure of grit or sharp sand.”

4. Don’t plant mint in borders

Is summer even summer if you’re not picking mint leaves and popping them in every refreshing drink possible? Don’t be fooled by its cool personality, though. One tip for growing herbs outdoors is to make sure you don’t accidentally let badly behaved mint steal all the space from its herby brethren.

“If you’re planting mint, it has a tendency to spread and overtake the rest of your plot, so to avoid this, plant in a pot to contain its roots,” explains Marcus Eyles, former horticultural director for Dobbies. Instead, he recommends:

“A great way to create a striking look is by lining the border of your herb garden with rosemary and lavender, which will create a hedge effect to contain everything, and you can trim it as needed.”

5. Sow biennial herbs in batches

Biennial herbs, such parsley and the biennial varieties of sage, are best enjoyed across the year if they’re sown in different batches. This means you’ll have herbs to hand at different stages of their life cycle across the seasons. Monty Don tries to have at least two lots of parsley on the go at once, for example.

“I make the first sowing in early spring to harvest from midsummer to the following spring, and a sowing in July will provide fresh leaves from October through to the following midsummer,” he writes.

“It will only germinate if the soil is damp and warm, so wait until May for outdoor sowings.”

6. Fertilise herbs every two weeks

All that glorious, aromatic foliage takes a lot of energy to grow. That’s why herbs can be particularly hungry, and if you want to regularly harvest their leaves, watering with fertiliser is a good habit to get into.

“Use a specialist feed... to provide the perfect balance of nutrients to help your plant produce tasty and aromatic herbs,” Baby Bio’s Lindley told us.

“Most varieties of herbs require plenty of water, so water generously once a week in the early morning or late evening and add a few drops of fertiliser every two weeks for optimum results.

“Ensure your pot has a drainage hole to prevent soil from becoming waterlogged, though, as this could ultimately kill your herb plant.”

7. Give your herbs enough room

If you have a small garden, you might prefer to grow your herbs outdoors in raised beds or another container. Don’t be fooled by the size of the supermarket pots we buy; herbs need lots of space if they’re to flourish.

“We suggest using a pot that is at least 10cm deep, or grouping them together in a trough,” says Julian Palphramand, head of plants at British Garden Centres.

“Tender annual herbs can even be sown year-round... just make sure to place them in a sunny spot facing south, receiving at least six hours of sun daily.

“To get started, fill your pots with compost, sprinkle the seeds and water them in. Cover with cling film until the seedlings emerge.”

8. Pair basil with tomatoes

One of our favourite salads is a simple caprese (tomato, mozzarella and basil). But did you know that basil and tomatoes are just as suited growing in your garden side-by-side as they are in your kitchen?

“Basil is best paired with its natural culinary partner, tomatoes,” writes Monty Don.

“If a tomato is growing happily, then basil will willingly share exactly the same conditions and regime.

“This means rich soil, water, sunshine and, above all, heat. Basil will not tolerate the slightest touch of frost and does not thrive when the temperature dips below 10°C (50°F), becoming leathery and bolting [when plants prematurely go to seed, meaning they’re of no use] during a cold spell.”

This is why unlike other herbs (such as mint and sage), you might want to leave basil in the greenhouse, if possible, unless you’re able to remain vigilant and bring it indoors if there’s a dip in temperatures.

Read our tips for growing the perfect tomatoes.

9. Chop back chives when they fade

If you have a shady garden, chives are an ideal herb to grow outdoors. Though it might really thrive when lavished with sunshine, it will still tolerate more shade and damp than many other aromatics. Monty has a quick tip to extend the longevity of chives:

“They develop lovely mauve balls of flower – which are edible – but as soon as the colour fades, the whole plant should be cut hard to the ground and taken to the compost heap,” he writes.

“This stops the stems becoming woody and encourages fresh, soft growth that will appear with almost miraculous speed. I cut mine back two or three times like this between May and September.”

10. Don’t forget to keep harvesting

Though you may plant herbs to simply create a more sensory garden, it’s important to keep picking. Regularly harvesting your herbs not only provides you with delicious ingredients, but it helps the plants to grow in a more visually appealing way.

“Simply pinch the tops off or snip with scissors and enjoy,” says Baby Bio’s Lindley. “Make sure you nip out the leaves at the top to encourage the plant to bush out and grow. The more you pick off and cut back, the more you will stimulate fresh growth and be rewarded with bushier plants.

“You can also freeze leaves for use in the winter months. We recommend chopping them and packing tightly into an ice-cube tray with water, then simply pop in the freezer. These can then be popped straight into hot or cold water for cooking or drinks, or added straight to hot pans if you’re making soups or sauces.”