Borago officinalis (Borage; AKA 'starflower') is an herb useful to humans as well as bees. The flowers and leaves have culinary value, and the seeds are used to make oil.
If you have ever come across a patch of Borago officinalis in full flower, and watched for a short while, you will more than likely have observed that the flowers were very popular with bees.
Borage is a self-seeding annual herb - one of the few “true blue” flowers in nature
It has attractive star-shaped flowers that turn from blue to pink as they age, and these paired with large fuzzy leaves add texture and a unique interest in the garden. Borage makes excellent green manure, the leaves and flowers make a calming tea, and the blossoms are edible.
You may well have seen quite a few other insects too, including pollinating flies of various types, visiting borage flowers; they attract a wide range of beneficial insects. This includes predatory insects that can help keep aphid and other pest numbers down. And once borage goes to seed, birds will benefit too – including a range of finches. And remember, once you have attracted the insects to your garden, the other wildlife will come to prey on them.
ITs prolific nectar and pollen production is what makes borage an invaluable plant in the pollinator garden.
A number of studies have included borage in their assessments of pollinator plants, but for the purpose of this page, I'm going to focus on a comprehensive 3 year study conducted in Poland and published in 2019 by Stawiarz et al.
Citation: Stawiarz, Ernest, Wróblewska, Anna, Masierowska, Marzena and Sadowska, Dagmara. "Flowering, Forage Value, and Insect Pollination in Borage (Borago Officinalis L.) Cultivated in Se Poland" Journal of Apicultural Science, vol.64, no.1, 2020, pp.77-89.
Some of the key findings from the study by Stawiarz et al were as follows:
1. Nectar secretion from borage flowers begins at the loose bud stage and lasts throughout the entire life of the flower.
2. The average number of flowers on a single borage plant was a whopping 953 single flowers!
3. The average life of each single borage flower was 21.2 hours, and plants had an average flowering time of 56 days.
4. Summary of the nectar and pollen provision of a single borage flower:
Average offering per single Borage flower: 4 mg nectar; 1.1 mg pollen X 953 single flowers per plant
5. That means that during the growing season, on average, a single borage plant can supply insects with 1.1 grams of nectar sugars (total sugar content derived from the nectar) and 1.1 grams of pollen!
6. A single square meter of borage crop can supply on average 5.2 grams of nectar sugar and the same weight of pollen.
Nectar, of course, is the reward that the plant gives in order to be pollinated. Nectar is usually just a drop at the base of a flower. Once sucked up by a bee, wasp, or butterfly, the flower refills its nectar supply, thus ensuring that the pollinators will come back. Some flowers take as much as 24 hours to replenish the nectar. Borage, on the other hand, takes only 2 to 5 minutes.
Borage continues to yield nectar even in cold weather making it a significant bumblebee plant. The plant’s downward-facing blooms prevents rainwater and morning dew from diluting the plant’s nectar.
The pollen provided by Borage is readily collected by bumblebee species, especially Bombus terrestris (buff-tailed bumble bee) and Bombus lucorum (Whitetailed bumble bee).
Pollinators that visit Borage:
Proportion Of Visitors To Borage Flowers
Honey bees (Apis mellifera) 29.50%
Bumble bees (Bombus) 22.20%
Other bee species 21.40%
Flies (Diptera) 18.50%
Other insects 8.40%
Borage can be grown easily from seed. It can even be direct-sowed in spring. You can either collect the seed from mature flowers, or just let the seeds drop onto the soil.
Borage has a certain earthy, coarse appearance and self-seeds prolifically, so be aware of where you plant it.
… and you can make borage flower ice cubes for your next garden party as well.
Final note: Borage is self-compatible. Its strategy to avoid self-pollination is protandry: stamens develop, or pollen release occurs, prior to the maturation of carpels or stigmas being receptive.
