Sunday, 11 January 2015
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?
We now have a sister website, My Open Garden, to promote gardens open to the public throughout Australia. We hope you will visit the site soon!
- By janice 2069 Monday, 12 January 2015
Thanks Deirdre, both helpful and interesting! Janice 2069 Thanks, Janice. Happy New Year. Deirdre
- By Kate 2070 Monday, 12 January 2015
Happy New Year all, I have missed you Deirdre! Question: Does a tree fern (hard trunk type) cause negative environment to other plants? Two Port Wine Magnolias in a hedge have been replaced a number of times below the "umbrella" of the plant, but the rest of the hedge fares well. Soil investigation of the area hasn"t produced any answers. Thanks, Kate. Hi Kate - see Richard"s answer below. Deirdre
- By margaret 2122 Monday, 12 January 2015
Thanks, Deirdre, fascinating and great advice! I always allow many plants to seed, and am amazed at the number of insects attracted to the flowers - an assortment of wasp or wasp-like insects, hover flies and various bees. Plants include Orlaya, Scabiosa, mint, thymes, basil, alyssum, many of the Asteraceae family, and Achillea. Lambley"s offered nigella seeds last year, with green flowers and I have a plant ready to flower, it has a large, flat flower head. That nigella sounds interesting. Good you have been able to grow achillea successfully. Your garden sounds like a banquet for the beneficial insects! Deirdre
- By Anne 2518 Monday, 12 January 2015
Welcome back and a happy and healthy horticultural year ahead for you and us your followers. I have used parsley flowers and I think celery as I noticed what a lovely colour they were in a mixed bunch. Margaret"s green nigella sounds fascinating. Lambleys is a nursery I would love to visit in summer. I think I did visit it many years ago but before it moved to its present location. Lambley Nursery is certainly worth a visit! Happy New Year. Deirdre
- By Marilyn 2250 Monday, 12 January 2015
Parsley is one of my favourites for tiny beneficial wasps also, though letting it go to seed is not popular with my better half. I presume that the picture of Tithonia is not taken in your garden? Much as we would like to see bumblebees in NSW, it might generate a bit of excitement in certain quarters. Well spotted, Marilyn! I should have added to the caption that this photo was taken in France. I have updated it now. Deirdre
- By Richard 2112 Monday, 12 January 2015
Happy New Year all! In relation to Kate"s question on hard tree ferns (Cyathea sp), I have not had any issues with them killing plants growing under them, and have camellias, Vireya rhododendrons, begonias and gardenia happily growing under a mature C. cooperi. They do have very fibrous roots and take a lot of moisture out of the soil, but I am unaware of any allelopathic tendency in terms of actively killing neighbouring plants. I also have a couple of C. australis near other plants. Thanks, Richard. I wondered if it was the root competition or maybe the shade aspect that is affecting the growth of Kate"s shrubs. Deirdre
- By Lynne 2479 Monday, 12 January 2015
Very interesting - thank you Deirdre. I have noticed that chive flowers and onion flowers are also very pretty. They may also have some sort of anti-pest qualities? Lynne Yes, Lynne - I just checked on that and they are attractive to beneficial insects. Thanks for the query. Deirdre.
- By Jan 2582 Monday, 12 January 2015
Happy new year Deirdre. Glad to know it"s ok that we have herbs flowering madly (even mint is looking pretty). It"s been wonderful to have so much rainfall and to see things flowering that would usually be struggling at this time of year. I did get to Lambley for the first time at the end of December. It was very dry in Ballarat, but the gardens were still lovely and it was great to see it in the flesh. David was kind enough to show my 7yo son a blueberry bush with directions to eat his fill. Sounds wonderful, Jan. I think that Lambely plants would be very suitable for your garden. Deirdre