A few months ago, a friend of mine presented another friend with a beautiful birthday bouquet of flowers, picked from her garden. One of these was an unfamiliar lacy froth of delicate pale greenish-yellow bloom. It turned out to be the flowers from a humble parsley plant, and we all exclaimed in amazement at how decorative it was. I have since discovered that parsley flowers are one of a number of blooms that can attract beneficial insects to our gardens: ones that will eat the bad pests that attack our plants! With one of my New Year's resolutions being to avoid using chemicals on pests in my garden, I decided to investigate this topic further.
Though you can send away for boxes of beneficial insects - which include such creatures as hoverflies, ladybugs, lacewings, parasitic wasps and flies, and various bugs - it makes more sense to me to attract them naturally into the garden, by providing nectar and pollen for food, and suitable places to shelter. It seems that, in general, beneficial insects are small and so have tiny mouthparts. Apparently, nectar and pollen from clusters of tiny, shallow flowers growing horizontally on a flat 'landing platform' are best for these creatures. Consequently, this means that plants of certain families are more beneficial than other families overall (though not all members of an 'attractive' family may be useful).
Parsley (Petroselinum crispum) belongs to the Apiaceae family of plants, the tiny flowers of which are formed into a simple or compound umbel: an inflorescence that consists of a number of short flower stalks that come out from a common point, rather like an umbrella! The flowers of many of these plants are favourites of beneficial insects. The family includes vegetables such as carrot, celery, fennel and parsnip, and many aromatic herbs, among them caraway, chervil, coriander, dill and of course, parsley. A few members of the family are grown purely for their lovely blooms, such as Queen Anne's lace (Ammi majus and Ammi visagna, pictured above left) and Orlaya grandiflora. I have always cut off the emerging flower stalks of parsley, coriander and chervil, as I understood that if left on the plant would weaken the plant: it was something of an epiphany to realise that these flowers could actually be helpful to my garden! I have resolved to grow more of these herbs and vegetables in my garden this year and let some of them completely go to seed - and I might even get some self-sown seedlings as a bonus. The plants actually have lovely foliage and flowers if we look at them objectively!
The Asteraceae (Compositae) family also has flat flower clusters: what appears to be a single bloom of many of these plants is actually comprised of many tiny 'disc' flowers in the centre, surrounded by larger individual strap-shaped flowers. The disc flowers of many of the members of the daisy family attract a number of beneficial insects. Particular favourites that thrive in our Sydney include yellow chamomile (Anthemis tinctoria), annual sunflowers (Helianthus annuus), Mexican sunflowers (Tithonia rotundifolia, an annual plant that I am thrilled to be growing for the very first time this year), signet marigolds (Tagetes tenuifolia, with small, single flowers and very lacy foliage: cultivar names include 'Tangerine Gem' and 'Lemon Gem'), annual pot marigolds (Calendula officinalis), Cosmos bipinnatus, Gaillardia species, Echinacea purpurea (pictured above) and feverfew (Tanacetum parthenium). Yarrow (Achillea species) also belongs to the daisy family and is a good beneficial insect attractant; however, I have never had much luck growing this plant in Sydney.
Other plants with clustered heads of tiny flowers that are useful for beneficial insects and grow well in Sydney include alyssum (Lobularia maritima, pictured above, said to be one of the most effective of all) and Scabiosa species and cultivars. Herbs from the Lamiaceae family of plants also usually have diminutive blooms, and many of these attract beneficial insects: basil, thyme, lemon balm, oregano and mints.
Growing a diversity of plants so that there are flowers all year round to provide food is the ideal to keep these insects in your garden. We also need to tolerate minor infestations of insect pests in our gardens so as to encourage the good insects to stay! As well as food, it is helpful to provide our insect friends with water (such as with a shallow birdbath, preferably with a few stones for them to land on) and shelter (leaf litter, shrubberies and tall perennial plants).There are rather cute 'insect hotels' for sale these days that have various bamboo tubes and drilled holes for insects to hibernate or shelter in! It is quite uplifting to think that we have an unseen army of insects to help us keep our garden pests under control. Who wouldn't plant a few flowers to sustain them in their work?
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