Flowers for Vegetable Gardens

Friday, July 16, 2010 by Jeremy Dore - Categories: flowers beneficial insects
< Back to the GrowBlog Index

I have always been more of a practical gardener than an idealist. Although it is nice to have an array of pretty bedding flowers I am not inclined to invest the time or space for such luxuries: for me each plant has to earn its place in the garden and be productive in some way. This doesn’t mean that my vegetable plot is devoid of flowers however. Flowers play an important role in any organic garden but the criteria for selecting them are different to ornamental gardens – it’s not the size or colour of the flowers that count but their attractiveness to the right kind of insects.

There are two classes of beneficial insects that I use flowers to attract:

• Insects that eat pests: Hoverflies, lacewings, ladybirds (called ladybugs in America) and others are all the very best protection a garden can have against the invasive pests that feed on crops such as aphids, mites, thrips, mealybugs and scale insects.
• Insects that aid pollination: Bees are the primary pollinators (both honeybees and bumblebees) and need as many good sources of nectar as possible given the current sharp decline in numbers. However, many other insects can help pollinate crops including wasps, moths, butterflies and certain species of beetle.

How do you select the best flowers for your vegetable garden? The key is to pick flowers that are rich in high-protein pollen and that provide sources of nectar throughout the year (known as insectary plants). Many highly-bred ornamental flowers fall short on these criteria so it’s important to choose flowers that are known to attract beneficial insects. Some seed companies now have specific ranges of flowers to do this but the information is often rather vague with few of them labelling which insect group each flower attracts. So here is my guide to the best flowers for vegetable gardening, all of which I have used successfully in my own garden. To make the list they had to be easy to grow, attractive and have plenty of beneficial properties:

	Calendula: Known as 'pot marigolds' but actually unrelated to the more common marigold family of plants (Tagetes), calendula is easy to grow and keeps flowering through the summer if you regularly pick off the seed heads. You can easily save the large curled seeds as they are easy to handle as well as drying and storing well.
	Marigold: The bright yellow blooms of the many kinds of marigold are good at attracting hoverflies, bees and butterflies and the strong scent of the French Marigold types is said to deter nematodes. Like Calendula they will grow in almost any kind of soil, are easy to save seed from and often confuse pests if inter-planted with vegetables.
	Chamomile and Daisy: Most composite flowers from the daisy family will attract a range of beneficial insects. The flowers may not appear to be stunning but hoverflies and predatory wasps love them. An added benefit of growing chamomile is that you can make delicious fresh herbal tea from the flowers.
	Poached Egg Plant (Limnanthes Douglasii): One of my favourite flowers for growing along the edges of raised beds. Not only is it great at attracting hoverflies and bees but it also produces lush green stems that can easily be dug into the soil when flowering is over.
	Onion and Garlic: It's not uncommon to have some onions or garlic bolt (shoot up flower heads) or produce much smaller bulbs than expected. Rather than pulling them straight up I like to leave these ones in the ground and let the flowers fully develop. Hoverflies love them and they look quite unusual and attractive too.
	Parsley, carrots etc. (the umbelliferae plant family): Again, leaving excess plants from this family to 'flower' attracts many beneficial insects such as hoverflies. Although not very colourful I do like the patterns of the flower heads.
	Comfrey: Bees love comfrey and it also provides the perfect source of nutrient-rich mulch for your crops. However, it is highly invasive, so make sure you check out our comfrey article first.
	Nasturtium: These do the opposite of attracting beneficial insects – they are highly effective at attracting blackfly away from your main crops – see my article on Trap Cropping for details. They lose their beauty once covered in blackfly but it is easy to remove the affected stems and dispose of them away from the vegetable plot.

Along with the above flowers, many green manures (cover crops) double up as excellent insectary plants. The following are particularly worth mentioning:

	Phacelia: I love this plant and can never bear to dig it into the ground. Because it over-winters well it provides the perfect nectar source for bees as they emerge from hibernation and its lavender-coloured flowers are quite distinctive. It can be left right through spring until the early summer crops need the space.
	Buckwheat: Equally good at attracting beneficial insects, this takes up less space than phacelia but consequently needs to be sown more thickly if using it as a green manure.
	Clover: Bees just love clover and honey bees use it to produce a delicious clover honey. Red or crimson clover is a fantastic source of nitrogen for the soil too, widely used in organic farming.

Mustards can be beneficial but, being part of the Brassica family, they will interfere with crop rotation. Mints are also good but are so invasive that they are best kept to containers and herb gardens. Finally it’s worth mentioning that dense bushes or low-lying perennial plants can be invaluable places for beneficial insects such as ladybirds to over-winter.

This wonderful collection of flowers may not be a common selection from your average local garden centre but they are all hidden treasures. By planting them you will be building up an almost-invisible army of beneficial insects that will be highly effective at controlling garden pests and much safer than insecticides. They may not be stars at the summer flower shows but I’d prefer them in my garden any day.