Companion Planting – easier than you think!

Companion planting is the growing of different plant species close together, for expected benefits in productivity – and it’s easier than you think.

It is hardly surprising that companion planting can seem to be a rather mysterious art. Many books and articles throw around statements such as “carrots love onions!” with little explanation or evidence, and in fact the expected benefits of companion planting come in many different ways.

Our guest blog this month on Companion Planting is from Naomi Distill, a very knowledgeable gardener and the inspiration behind Incredible Edible St Albans, a project of FoodSmiles St Albans and a past winner of Environmental Champion in the St Albans Mayor’s Pride Awards.

Every garden is an eco-system – with more organisms than we know – affecting it…

Benefits of Companion Planting

  • Pest control 
    • using plants which repel pests by smell
    • using plants which attract predatory insects to eat pests
    • by trap-cropping (using alternative plants as decoys to attract pests away from the main crop)
    • by disrupting the odds of a pest successfully landing on its desired host plant 
  • Increased pollination (using plants that attract extra pollinators)
  • Maximising use of space or time (e.g. catch-cropping by planting fast-growing extra crop between a slower-growing main crop, or growing plants with different root depths together to make the most of root space)
  • Maximising efficiency by grouping plants with similar needs
  • Exploitation of another plant’s physical properties (e.g. one that shades, supports or protects another, or one that provides groundcover to reduce weeds and evaporation)
  • Effects from chemical secretions released into the soil by roots
  • Adding nutrition to the garden (i.e. nitrogen-fixing plants or those with very deep roots can accumulate nutrition and make it available to other plants).

Companion planting is an inexact science

Though beginners often get started with companion planting using a long list of ‘rules’ that simply pair plants together – or forbid pairing them – these rules fail to take into account the complex relationships found in a garden, and can make veg-plot planning feel like doing an impossible jigsaw! But companion planting is an extremely inexact science.

Every garden is an ecosystem, with more organisms than we know affecting it: feeding from it, fighting for survival in it, and putting inputs into it. Soil life below the surface is even more complex, and the unique mineral make-up of your soil has its effects too, and then there’s the microclimate of your garden to consider. No two plots are the same – and no two years are the same.

Learning the Hard Way: Mistakes and Myths

The first year this trial of companion planting worked a dream; not an aphid in sight and the lettuces seemed better than ever. The second year however, there were soon aphids all over the lettuce – and the coriander too! Its repellent power could obviously not be relied upon.

As I looked round the allotment at all the other plants nearby, I quickly realised there were, of course, other factors in play when you tried companion planting. Perhaps something else nearby attracted the aphids? Or a shortage of other food plants elsewhere brought them? Maybe those lettuces were particularly attractive? Could there have been higher numbers of the pest this year? The possibilities were endless.

“Little did I know that horseradish plants are thugs, with deep roots, and very hard to remove!’

Horseradish and Potatoes – yes or no?

Another memorable lesson of trying out companion planting was realising how foolish it had been to plant horseradish throughout my potato patch. I had read that horseradish repels potato-munching eelworms and wireworms. Little did I know then that horseradish plants are thugs, with deep roots, and very hard to remove! How anyone can make that pairing work is a mystery to me!

Onions with carrots? Sage with brassica?

Two pairings often quoted in companion planting books are onions with carrots (to repel carrot fly), and sage with brassicas (to repel white butterflies). However, in truth it seems that you need far more of the repellent plant than the intended crop in order for the rules to work well. Companion planting here means several rows of onions per row of carrots, and many sage plants per brassica plant. It might just work out if you don’t eat very many carrots, but who can use that much sage?

Green Beans and nitrogen

Another common companion planting suggestion is that beans should be grown close to crops that would benefit from the extra nitrogen fixed by their roots, however this is not supported by science (see this article, or this). Though the bean roots may gather nitrogen early on in life, most of it is used by the plant for the formation of flowers, pods and seeds, and only a negligible amount remains or goes into the soil.

Cabbages with calendula

An Easier Method: Companion Planting- the four rules

So I’d like to propose a different approach to companion planting, focusing on biodiversity and natural design. This method means including as many useful plants in the garden as possible, in any layout. Our Incredible Edible gardens use this approach and I have used it in my allotment and garden for years, and there are only four rules:

1. Right plant, right place

Plant the sun-loving crops in the sunny spot, the shade-tolerant ones in the shade, the damp-loving ones in the wet corner. Keep the tall ones out of the worst of the wind, if possible. Under the trees in the Incredible Edible gardens we have adopted a forest gardening approach. We choose low-maintenance edibles that happily grow under trees in the wild.

2. Mix things up

Minimise traditional rows, and interplant with abandon! Add flowers and herbs to your veg patch and veggies to your flowerbeds. When a pest settles on a new plant, don’t let it find a whole tasty row all laid out and waiting! Make it harder for them. This intermingling approach makes crop rotation much less important, which is a help in any small plot where rotation can be tricky.

3. Common sense first!

Let common sense and your own observations rule. Use trial and error to find what works best in your own garden and your own microclimate. Think logically about the relationships between your plants, and the physical shade and shelter they provide. If you’re not sure how big a plant will get or how long it will live, look it up! But don’t overthink it. With gardening you always get another chance next year.

4. Maximise plant diversity

Employ plenty of great all-round companion plants to increase diversity: those listed below will enrich your garden, whatever plant you grow them next to. The more biodiverse your garden is, the more easily it will find a healthy natural balance. It will give you better crops, with fewer problems. Animal diversity helps too, so keep your garden free of pesticides, and welcome wildlife by providing plenty of habitat.

Eight best companion plants to use in your garden

Eight Best Companion Plants To Use In Your Garden

Edible Alliums

Garlic, chives and onions repel a variety of pests – including the four legged kind. They also attract pollinators with their flowers. Their roots accumulate antifungal sulphur in the topsoil which can benefit nearby plants. They are a great companion for virtually anything!

Calendula (pot marigold)

This is a brilliant plant for a veg plot, as it attracts a wide variety of insects including aphid-munching hoverflies. It is edible and medicinal, flowers from early till late and often overwinters (cut back the dead bits and it’ll often reshoot from near the ground). It is always happy among veggies and easily self-seeds to save you a job next year.

French marigold

Another powerhouse in the garden; repelling pests, attracting beneficial insects, and releasing secretions in the soil which keep nasty nematodes away.


As well as attracting pollinators, these are an excellent ‘trap’ crop, attracting blackfly and cabbage butterflies to lay their eggs away from your main crops. Once they’re infested though, don’t let the pests breed in your garden! It’s better to dispose of the infested parts right away.

Flowering herbs: mint, oregano, marjoram, thyme, dill, fennel, lovage, lavender, hyssop, camomile

Herbs are a worthy addition to your garden for their culinary benefits alone. But they also attract a huge variety of insects, many repel pestilence, and some (especially camomile and parsley) are said to improve the health and flavour of nearby plants in more subtle ways through the soil too. Note that lovage and fennel are larger plants than most here. Give each a good space to itself and note that they can get very tall. In fact, their height will attract insects from even further afield!

Comfrey or stinging nettles

Though you’ll want to give these a corner of the garden to themselves (there is no digging comfrey out once it’s in!) they can provide a really useful service in the garden by bringing extra nutrition up from the depths of the soil with their deep roots. Harvest this nutrition by cutting the leaves a few times a year and adding them to your compost heap, or scattering them on veg beds and leaving them to decompose. You can also leave them rotting in water to make a (smelly!) concentrated liquid plant feed. Comfrey attracts bees too, and stinging nettles are an important food plant for certain butterflies.


Experiments showed that growing clover under brassicas consistently reduced the success of cabbage moths looking for a host plant, thus bringing a protective effect. What’s more, the clover offers bee-attracting flowers, and anytime it gets too much you can dig areas of it into the soil (preferably in spring before flowering) for a nitrogen-boosting effect.

Nectar-rich annual flowers (e.g. sunflowers, borage, cosmos, cornflowers, zinnias, scabious, echium)

A few favourite annual flowers such as these will fill gaps in the garden and spread insect-attracting colour anywhere; your local pollinators and predators will thank you! Many will self-seed too (stop deadheading by late October to allow this) and give you a new round of flowers for free next year.

So put the rulebooks away, focus on increasing the diversity in your garden, and always let common sense rule!

Local Food Gardening Events: find out more

Come and grow with us! Volunteer at the Incredible Edible gardens on the second and fourth Sundays of each month. Email Incredible Edible here to join the mailing list or find out more about Incredible Edible St Albans

See more about FoodSmiles here

Find out about Sustainable St Albans Open Food Garden summer programme

If you live in Sopwell ward, you can try some food gardening at the Grow Community Sopwell Community Garden

SustFest22 Gardening Events

During SustFest22 (15-31 May) there are loads of gardening events to look out for.  

The programme comes out on 14th April, on social media and the Sustainable St Albans website. Here are just a few events, to whet your appetite! 

  • Grow Community Sopwell Community Garden Open Day including Seed & Seedling Swap, 15th May, 10:30am-12:30pm
  • ‘Adopt a plant for your pollinators’ at Greenwood URC, May 17th and 19th,    2:30-3:30pm
  • Visit the CDAH Community Garden on Hixberry Lane, 19th May, drop in 10:30-2pm
  • ‘How to grow Asians herbs and spices’ with HAWA, also 19th May, 12-2pm, at the CDA community garden on Hixberry Lane
  • ‘Gods Green House’ plant sale and eco garden tour, at St Paul’s Church Blandford Road, 21 May, 10:30-12:30pm
  • ‘Come and Grow’ at Incredible Edibles, Russell Avenue, 22nd May 1-4pm
  • ‘How we built an eco garden for next to nothing’, at Marshalswick Baptist Free Church, 24th May, 2-3pm
  • FoodSmiles open day, Hammonds End Farm, 25th May, 1:30-4pm
  • Grand Opening of the George Street Canteen Wildlife Garden, 29 May, 11-3pm

Look after local trees, and they will look after you!

St Albans has numerous special places – in the parks or little walkways, overhung with native trees, or sentinels in our own roads. They provide familiarity and comfort.  Read on to find ways to look after local trees.

This blog, from founder members of Trees of St Albans and local tree wardens Anthony Helm and Amanda Yorwerth, celebrates the beauty, and vulnerability, of the trees which surround us, and how you can help. 

Celebrate trees!

Looking after trees is as much about care for ourselves - this blog celebrates trees and explores simple ways that you can help your local landscape.

We have grown up with them.

They act as touchstones: we want to explore more.

Woods; in fiction and in real life, are highy evocative places.

The loss of tree canopy matters

Sadly, many trees are under threat, and some might not be enjoyed by those who will succeed us.  The reasons are varied.  

Some, like cherry trees, were planted long ago and have come to the end of their natural life; others are succumbing to disease, like ash dieback, or pests.

  • Vehicles are in many places destroying the soil through which trees breath, move and feed
  • More are being lost because of building developments or the possibility of legal actions
  • Others are felled under the accusation of being ‘overgrown’ or ‘casting shade’

Trees offer ‘silent benefits’

All this matters not just because trees are beautiful.  More importantly they provide a myriad of unseen services: shelter from winds; cooling from increasingly harsh heat waves; filtration of harmful airborne particles; baffling sound from noisy roads; rejuvenation of soil; amelioration from devastating flooding; habitats for many species.  

If all this were not sufficient, trees absorb carbon dioxide (the principal greenhouse gas) – and provide oxygen – without which humans would suffocate.

Old trees need protection
To look after local trees, as a matter of the greatest priority, we must maintain and rebuild our local tree canopy. 

“The loss of a significant mature lime or 150-year-old plane tree in a city road will have an immediate aesthetic impact but also a serious, unfelt ecological impact.”

One mature tree is worth thousands of new plantings.

A major focus for everyone in St Albans District wanting to look after trees must be to work a lot harder to retain these silent friends; we should stand up and speak for our trees, with neighbours and our political representatives, at all levels.

New trees should be planted 

We have to renew as well, and pre-pandemic proposals gave the prospect that thousands of trees would be planted in the District.  Now organisations, families and many individuals look after local trees by actively planting, or are planning to plant, trees over the next year or so.  

The Queen’s Green Canopy initiative, and other projects aim at tackling climate change and improving the environment.  

St Albans District Council, Herts County Council, the Parishes, and many others, e.g. schools, are involved, with local people, especially children, keen to assist, in the significant plantings of very young trees.  Councillors, from their own budgets, are also planting single trees on highway verges and in green spaces.  And we are seeing that sustainability is inspiring the planting of community orchards in small pockets of land for local food.

If you are part of a group which manages pockets of land – a school, a church, a parish council – then why not plant a tree (or more!) as part of the Queen’s Green Canopy?

Despite all the above, there is a net loss of tree canopy in urban areas and each of us can do our own bit.  

We can all do our bit to look after trees! – planting in the garden

Those with gardens can:

  • Find a space for a fruit tree
  • Replace a fence with a hedge of native plants (especially at front of properties)
  • Gardening is about possibilities and change; nowadays the options for species selection are vast. See the RHS guides to trees, hedges, and flowering hedges.

We can also spend more time looking around our immediate locality; seeing which trees are damaged or diseased or need releasing from a choking tree-tie.  In the dryer months new trees will need watering.  Pop out and water the young trees near your house, or on your regular dog walk. 

We can all do our bit! – caring for street trees

We, as individuals, can do the detailed monitoring and undertake the small actions that councils can’t. 

Report major issues here –

Care for trees, and you care for yourself

It can create a spring in your step. But you already knew this….

Looking after our own patch (our borrowed landscape) is a pleasure.  It is not difficult or time consuming and can be built into normal activities.  It allows us to form our own connection with nature; release tensions; make us physically stronger and build creativity.  

Get more involved

To follow up and support local trees, why not become an SADC Tree Warden, join a Wilderhood Watch Group ( and sign up to Trees of St Albans on Facebook?

SustFest22 – If you are in a local group and planning an action to support trees – why not do it as part of the 2022 St Albans Sustainability Festival? See more here.

Fruit, Veg & Wildlife in a Smaller Garden

Our garden is not very big, and we have three different priorities for it: fruit and veg growing; wildlife; somewhere to sit and entertain. So, we’ve had to be creative with space.

To highlight 2021 Open Food Gardens summer programme this blog is about growing food at home by local gardeners, Nigel Harvey and Clare Hobba. They paint a picture of what food is possible to grow in a small garden when approached with a love of nature and a desire to #GrowYourOwn.  

Re-imagining the front garden #growyourown

For most people, a front garden is an area that we keep neat for the sake of others, but don’t get much benefit from. 

We use our front garden for growing fruit and veg

However, we use our front garden for growing fruit and veg at home.  Paths and low walls add structure, so it doesn’t look untidy. Bright flowers and shrubs grow round the edge and attract insects.    

Artichokes, gooseberries, redcurrants, blackcurrants and whitecurrants grow on one side; kale (curly, and black), beetroot, garlic and courgettes on the other. Not to mention dwarf versions of pear, apple and plum trees.  We kept a small cotoneaster tree which was in the garden before we arrived and it provides nectar for bees in summer and berries for redwing in winter.  All of that, just in the front!

“to save space we like anything that climbs upwards”

Gardening at the back

At the back, another patch yields kohl rabi, French beans, lettuce and chard.  In the little greenhouse, Nigel grows chilli and bell peppers, aubergines, cucumbers and three varieties of tomatoes, On the patio we also have physalis and cucamelons.  Patio pots also hold a great variety of culinary herbs.  

Vertical Growing

To save space, we like anything that climbs upwards and are experimenting with ivy gourd, tayberry and even a kiwi fruit vine. 

Watering, compost and fertilising

The plants are watered mostly from four large water butts which collect rain from the roof.  We make compost in a bin tucked behind the greenhouse and supplement it with llama poo from a local farm.

Gardening for nature

“the small pond attracts newts and frogs”

Insects are attracted by profusely flowering plants such as the hot-lips salvia. Bug and bee hotels offer them the chance to stay and to hibernate. Similarly, the small pond attracts newts and frogs. Nearby a pile of old wood and tiles gives them somewhere to over-winter.  All manner of birds arrive for the birdbath and squirrel-proofed feeders.  And we still have enough space for some seating from which to watch them!

Clare Hobba

Bug Hotel at the Herts and Middlesex Wildlife Trust Wild Garden in St Albans

Want to know more?

How to Build a Bug Hotel

Pollinator Plants for insects

Recycled Wood for Garden Projects in St Albans

Vertical Veg Growing

Open Food Gardens Summer Programme 2021

Want to visit more food gardens?  Sustainable St Albans runs a summer programme of Open Food Gardens. It is like Open Gardens but with food growing too! These aren’t perfect show gardens, they are real gardens, owned and shared by real people, all of whom share a love of growing their own fruit and veg.  You can drop in for ten minutes or stay for two hours.  Find the dates of this year’s open gardens plus a range of videos on our website.

See the 2020 video tour of this garden below – but why not visit it on Sunday 20 June to see how it’s doing for this year – and talk to the gardeners yourself.

Open Food Gardens programme 2021

Causing A Splash to Save the River Ver

Now that IS excessive water use! This incredible 10,000 litre bathtub will be in the town centre on Thursday 27th and Friday 28th May 2021 during #SustFest21. It is all part of Affinity Water’s new movement SOS: Save Our Streams, calling on people in St Alban’s to waste less water to save our streams.

Affinity Water writes about their latest campaign to encourage local residents to #savewater and #SaveOurStreams #RiverVer

In October last year, Affinity Water ran pilot scheme ‘Save 10 a Day’ in St Albans and District to address the issue, which saw residents saving more than 700,000 litres of water a day. New movement SOS: Save Our Streams builds on this success and is asking us all once again to do all we can to save our beautiful local chalk streams.

Large bathtub with Save Our Streams written on the side.
The bathtub is 125 times larger than your average tub.

Coined ‘Britain’s Great Barrier Reef’, chalk streams like the River Ver boast clear water from underground springs, and are more endangered than both the Bengal tiger and black rhino. In St Alban’s we’re using 6% more water than the national average, putting these iconic natural gems at risk.

While you’re marvelling at a bathtub 125 times bigger than your average tub, make sure to speak to Affinity Water’s team. They’ll be able to support you to make simple changes at home to waste less water through the new website  

After answering a few questions about how you use water, provides you with your exact household water usage stats, a free water-saving kit and tailored advice. You can also view footage of Sandi Toksvig performing stand-up comedy live from the River Chess in an exclusive performance for the campaign.

If you take a selfie with the bath, don’t forget to tag @AffinityWater in in your pictures!

Towards a Wilder St Albans

Would you like to see water voles reintroduced to the River Ver? What about the ‘wilding’ of some the green spaces across the district, to increase wildlife habitats? Good news!  In April 2021, Herts and Middlesex Wildlife, in partnership with St Albans District Council will be launching a pioneering project, Wilder St Albans.

Tim Hill, Conservation Manager at Herts and Middlesex Wildlife Trust, describes how the project was developed and what it hopes to achieve.

Wilder St Albans aims to increase biodiversity – natural habitats and the species they support – across the District of St Albans. We will encourage and support practical action by the local community and look for natural solutions to the climate and ecological crises, like changing mowing regimes and allowing trees to grow.

“It couldn’t come a moment too soon… Hertfordshire’s ‘State of Nature’ report highlighted the immediate need for action to address the ecological and climate crises…”

It couldn’t come a moment too soon.  The Trust’s ‘Hertfordshire State of Nature’ report was launched in March 2020, highlighting the immediate need for action to address the ecological and climate crises, and to reach our target to secure 30% of land for wildlife by 2030.  Wilder St Albans is a great example of how communities and organisations can come together to make a real difference and play their part in nature’s recovery.

Brimstone butterfly

This all began with the community taking action. Loss of biodiversity, along with the climate crisis, caused a group of concerned residents to form the St Albans Environment Action Group during 2019. Herts and Middlesex Wildlife Trust together with elected members of St Albans Council worked with the group to address how these concerns could be tackled at the District level. 

“This all began with the community taking action”

At the same time, the Council was developing a Net Zero Carbon Action Plan and Sustainability Strategy. Based on experience gained through biodiversity action planning and conserving Hertfordshire’s globally rare chalk rivers through a partnership approach, Herts and Middlesex Wildlife Trust proposed ‘Towards a Wilder St Albans’ to the District Council – a collaborative project to enable people to act locally to address these global issues.

The project will raise awareness of the habitats and species of the city and facilitate community participation to achieve more wild places, bigger wild places, better managed wild places and connect them up to create a resilient ecological network. 

A collaborative Wilder St Albans Action Plan will be developed through the project and shared online, with the opportunity for local action groups to update and highlight their own local activities and contributions..

In March, the Trust recruited a Wilder St Albans Project Officer, Heidi Carruthers who will run the project and help local people to become involved.

Heidi Carruthers – Wilder St Albans project officer

The first piece of work will be to carry out a full audit of the habitats and species of the District, working with the Herts Environmental Records Centre. This will inform project development and decision making, and will include the production of maps to be incorporated into the Wilder St Albans plan.

The online plan ‘will be used to engage local residents with the project so that they can join in with or take forward their own practical action.’

Core to the project will be the design and development of a new web-based plan, with the aim for this to be a live record of action and proposals. The online plan will be a powerful tool to promote the project, gather ideas and record positive activity and progress. It will be used to engage local residents with the project so that they can join in with or take forward their own practical action. Local stakeholders will be trained to help  manage the online plan, ensuring it remains fresh and up to date.

In addition to the project webpages and local media coverage, the project will be promoted in partnership publications and online. National and regional media coverage will be sought by Herts and Middlesex Wildlife Trust as part of the Wildlife Trusts’ national programme of activity.

 One of the first major wilding projects will be the reintroduction of water voles to the River Ver in 2021.

Nationally, water voles have declined by over 95% over the last 60 years and were last recorded in the Ver in 1987.

Working in partnership with the Ver Valley Society and landowners in the Ver Valley, the Trust will be introducing 75 pairs of water voles to the river in July. In addition, across the city, ‘wilding’ of open spaces will be taking place through the revision of mowing regimes aimed at increasing wildlife habitats.

Wilder St Albans will be launched in April. If you would like to get involved in making the city a wilder place in any way, please contact Heidi Carruthers, the project’s People and Wildlife Officer –

Tim Hill – 3rd March 2021

Editor note: Kenneth Grahame wrote Wind in the Willows just over a hundred years ago. Since then, many of the UK’s wild places have been lost…. See more about rewilding on the Herts Middlesex Wildlife Trust website