Fiann Ó Nualláin goes with the flow of growing plants in partnership and discusses nitrogen-fixers.


Continued success in garden with companion planting

Fiann Ó Nualláin goes with the flow of growing plants in partnership and discusses nitrogen-fixers.

Continued success in garden with companion planting

Last week we looked at companion planting with culinary herbs and how they could improve the flavour and health of other herbs, crops and ornamental plants grown nearby.

This week I am in the middle of planting out my potatoes and some other crops that also benefit from some good company so I’d like to keep that theme going and explore what combinations are good in the vegetable garden.

When it comes to potatoes and companion planting there is often a long of list of don’ts: Don’t plant with asparagus, carrots, strawberries, fennel, raspberries, tomatoes, turnip, cucumbers, onions, sunflowers, squash, and pumpkins.

All are reputed to either weaken the spuds defences, or worse, assist blight. More than any other plant apart from brassicas, we tend to employ crop rotation to keep our potato crop healthy. But there are so possibilities if not outright dos.

I often dot a few wigwams of green beans among my potato patch as the nitrogen fixing beans will enrich the soil and my yield.

I did try a border of horseradish (Armoracia rusticana) a couple of times as it is a plant with root and scent secretions reputed to deter potato bugs and seems also to facilitate more disease-resistant potato tubers.

Horseradish is a bit of a beast and not easy to move about and keep pace with rotations. However, coriander (Coriandrum sativum), tansy (Tanacetum vulgare) and marigolds, both pot and French, all seem to have a similar effect on potato crop health, so more and more I rely on those.

In particular with the tagetes, which have root secretions that harm nematodes and wireworms that may infect your potato tubers.

Tansy has a reputation of deterring ants, mites and insects, but as it’s not an edible crop and its herbal uses are limited I only grow a small batch which I use as a decoction to spray about the garden and polytunnel.

Coriander however is a favourite of mine as a culinary herb and as it reputedly enhances the flavours and growth of asparagus, chervil and spinach when planted nearby, it’s a great excuse to grow more of it.

I dot it about the garden as it certainly does draw in beneficial insects too and that’s a big part of companion planting — to get the predators next to the pests.

When it comes to the marigolds there are two different species with that moniker: the French (Tagetes spp) and the pot (Calendula officinalis), but both are beneficial in producing natural pesticides (by chemical secretion into the root zone and by utilisation in a herbal tea to cool and spray onto infested plants).

They both attract hoverflies and other aphid-munching predators. I will line my potato patch with tagetes as it is also has a rep of protecting potatoes from viral and bacterial infections.

Calendula is one of those deter and decoy plants, it does repels tomato hornwoms and even asparagus beetles but it also attracts caterpillars and aphids so is often planted away from veg as a trap plant, to lure those pests away from precious edibles.

Same with nasturtium to keep blackfly off your beans — and aphids and cabbage white larvae off your cabbage. I love the vibrancy of the orange flowers and I use a lot of the petals as a garnish, but also in tea and herbal treatments.

There is no harm in having a pretty allotment or making your veg patch more of a potage — mixed with herbs and flowers.

The flowers will attract pollinators and also beneficial insects, some can be cut for the table or as a treat for the eyes as you water the tomatoes.

They don’t have to compete for space, you can use containers and make them mobile predator-delivery-systems.

On that last note, I am a fan of growing alyssum (Lobularia maritima) in pots that I can reposition to spots that require some predatory wasps to check the populations of pests.

However, even something like container petunias can attract the beneficial insects that feed off leafhoppers. It’s not all about flowers that attract bees because predatory wasps, lacewings, hoverflies and the full retinue of beneficial insect will pollinate too.

When it comes to bees, I find thyme and borage (Borago officinalis) to be supreme attractors and both are a great companion plant for tomatoes. Borage, in particular, deters tomato worms and aphids. Check last week’s article online to see the benefits of thyme.

Nasturtiums I adore — as edible petal and peppery leaf but also as a companion plant — when planted with cucumbers they will help improve flavour and growth, as well as deterring aphids and cucumber beetles.

If given the company of the cabbage family (broccoli, cabbage, kale, kohlrabi and Brussels sprouts) the yields are healthier as nasturtiums also deter Japanese beetles, cabbage looper and cabbage worm.

When it comes to apple trees an underplanting of nasturtium can be utilised to repel the codling moth while an underplanting of chamomile is said to boost flavour and inhibit apple scab.

Chamomile has a tonic effect, much lauded in herbal and medicinal books, but it is also tonic in its tea form as a cooled foliar feed to any ailing plant.

Parsley and marigolds repel asparagus beetles, and asparagus works well in the company of basil, tomato and nasturtiums. Beans do very well with cabbage, cauliflower, carrot, cucumber, celery, and corn. Dill attracts beneficial wasps that feast on cabbageworms.

Beets work with broccoli, lettuce, onion, sage. Leeks quite like similar (high potash) growing conditions as celery and celeriac while aromatic plants such as leek, onion, garlic and even lavender, mask the aroma of carrots and brassicas and so help keep them a little more pest-free. It’s worth a try.

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