How to Recognise a Nectar Flow.

Waiting for the flow: migratory beekeeper positions 17 colonies near field of OSR.
Commercial beekeeping in New Zealand. Photo by Linton Chilcott.

This is the longest cold spring that my beekeeping friend and neighbour David can remember and he’s been keeping bees for a lot longer than I have. Despite bright sunny days this week the highest temperatures reached only 12-13 degrees Celsius. Everything is late this year and the swallows still haven’t reached Piperhill though I saw my first glimpse of them on my way into Inverness this morning. Last year at this time they had been here for a week. Likewise, the plum tree finished blooming last year on the day that the first blossoms opened last week. The oil seed rape, OSR, is also a week late.

A long row of 17 hives appeared next to the field of OSR near our apiary this week which prompted me to get the bait hives ready. You can see the New Zealand set up of 4 hives to a pallet for comparison. This arrangement has the advantage of having entrances facing different directions thereby reducing the risk of drifting and spreading of disease and varroa. Also, when colonies are placed in a long row the end hive supers may not be well filled due to drifting and foragers returning to the wrong hive. Because they come bearing nectar, and smell cabbagy like all the other foragers, they are not likely to be arrested at the entrance by the guard bees.

Pallets of 4 hives can be easily lifted by forklift truck for loading onto transport. There are different ways of managing migratory beekeeping that certainly all require hard work and skill. I’m just pleased not to have to move ours anywhere since the bees only have to fly around 400 metres to reach the nearest field. However, I’m keeping up my weekly varroa monitoring as this is a time when our colonies will mix with others and may pick up more varroa in the field.

Is Nectar Coming in?

One of my favourite fields with Neolithic standing stone near the bottom. Note glacial undulations.

I know that the bees are working on OSR because the pollen loads in their corbiculae are yellow, and their hairy faces are dusted in yellow pollen too. But what about a nectar flow? By a nectar flow we mean the time when a plant is flowering and secreting the heaviest amount of nectar. Several factors affect nectar secretion and I’ll mention them in a minute, but let’s stick to OSR for now. I know that there is no nectar flow on here, yet, though the field is a vibrant yellow today: it is too cold. It needs to be around 16 degrees C for OSR to secrete nectar, and 20 degrees C is ideal for a great flow. Ok, so it might secrete nectar at lower temperatures and the bees will be collecting some now but there is not the rip roaring flow we need to fill the supers. The nights are very cold and frosty which is not promising and temperatures next week are forecast to drop to 8 degs.

Weighing the light poly hive using “luggage” hive scales at the back,and doubling the weight as instructed.
This hive weighs 16.36kg.

I’m weighing one of my hives weekly to study weight gain and loss and it is not yet gaining weight which it would be doing on a good nectar flow. I’m not yet hearing the contented-sounding evening hum in the apiary of the older house bees working the honey factory up in the supers They process nectar into honey partly by fanning their wings to evaporate off the water thus reducing it from between 40-80%, depending on the different flowet, to around 18%. Apple for example has a low sugar levels so the nectar will around 80% water. You can’t miss this evocative sound on a warm still evening alongside a glorious scent, even if slightly cabbagy in this case. It has been said that heavily nectar laden foragers return to the hive with backlegs postioned dangling forwards but they come back so fast during a flow I have difficulty seeing their backlegs. I’ve never apprehended a forager to squeeze its abdomen making it regurgitate nectar, but that would be one way of finding out if they are collecting nectar, but not necessarily indicating a flow. You measure the water content by placing a drop of regurgitated nectar on a refractometer and it will be between 40-80% water if nectar.

If you’re like me and are always looking to see what the bees are up to, you will notice far fewer foragers at the watering holes when there is a nectar flow on. I have a few different water sources to keep an eye on in my main apiary. The neighbour along the road, whose garden is accommodating a couple of our colonies, noticed a decrease in water collectors over the last few days which is a good sign.

This afternoon I checked the strongest colony’s super to find only a few nectar filled cells. They will have been using the current income and refilling the brood nest. What’s disappointing is that next week is to be cold too. Hopefully we get a couple of warm weeks in May to fill the supers, but OSR flowers for a shorter period than it did in the 1970’s when it might have gone on flowering for 45 days. Now flowering mostly lasts for around 4-5 weeks. To be honest, I don’t even know if this crop is OSR for the biofuels industry, or Canola for the food industry so I will ask Cawdor Estates farm manager next time I see him. Canola was created in Canada and means Canada low acid since erucic acid levels need to be below 2% for human consumption. OSR has high levels of this acid.

Migratory/commercial/proactive beekeepers build up colonies in advance to be ready for this crop so that no time is wasted in filling the supers. They feed a 1:1 stimulative sugar syrup. The colony thinks that there is a natural nectar flow on and it is time to build up for the season so the queen increases egg laying and the colony expands with the deep box/s bursting with brood and bees.

I don’t build up our colonies in this way. I let them do it naturally on the OSR because I’m happy with just one or two supers of honey per hive. I only sell honey locally and mostly from my doorstep.

Know Your Local Forage.

Over the years, I’ve built up a calendar of nectar producing plants in my area working on the assumption that the foragers probably only fly up to around 3 miles from the apiary, and usually not even that far. They can of course fly further than that if necessary, but around here is plenty of forage all year round. The weather and climate determine the nectar flow to a large extent, and though there might be plenty good forage flowering it may not be yielding nectar.

This week sycamore tree flowers unfurled and this would give a great source of nectar if our bees were not attracted to OSR with its higher sugar content. I once tasted dark delicious sycamore honey. The late Ian Craig, MBE, (for services to beekeeping) one of Scotland’s greatest beekeepers brought a jar when he visited me to examine my beekeeping skills for the Scottish Beekeepers’ Association senior practical exam for the Apiarian Certificate. He lived in an area without OSR for many miles.

If you are not sure what plants are good for bees, I can recommend Plants for Bees by Kirk and Howes. I like also Dorothy Hodge’s A Calendar Of Bee Plants. You can buy these books from Northern Bee Books.

Other Factors.

Soil moisture, relative humidity, soil pH, and differences in plant variety all affect nectar secretion. Some plants like heather, Calluna vulgaris, grow on acidic soil as do most plants in the Ericaceae family. Plants like rosebay willowherb, gooseberry and borage secrete high levels of nectar, and in some parts of Europe they have secreted more than 3mg sugar per flower in 24 hours which seems a lot to me.

I find plants fascinating and that some flowers such as phacelia secrete more nectar from the flowers at the bottom of the plant than the top. Honey bees prefer the lower flowers of rosebay willowherb and tend to move to the lower flowers of other nearby plants rather than move up the plant to reach those top flowers. Flowers on thick bramble (blackberry) shoots produce more nectar than those on thin shoots.

We know that the age of the flower and plant can affect nectar secretion and this is why migratory beekeepers taking bees to the heather prefer areas that have been burnt (muir burning) as described in a previous blog. The young shoots feed the grouse and the flowers on the young shoots produce more nectar for our bees.

Hollows with poor air drainage affect flowers and nectar production which is why beekeepers place hives on sloping south facing sites on heather moors.

If it is too wet nectar is diluted in some open flowers from the Roseaceae family such as apple. Too much hot sun and wind can dry up the nectar and one thing for certain is that we cannot control the weather. We can be observant though and watch for a dearth of nectar in the season that might adversely affect our bees.

The June Gap.

I haven’t noticed a June gap for some years but we can get one. June is often a month of nectar dearths. The OSR fields become green towards the end of May. This is our cue to remove the supers before the honey granulates on the comb.

The problem is that the summer flowers such as bell heather, clover, lime, bramble etc might not yet have started yielding nectar in June. An observant beekeeper keeps an eye on colony stores, and notices perhaps that the bees are more defensive than usual during a June gap. Robbing is easily provoked and drones may be evicted early to conserve stores. Pupae may be thrown out of the front entrances in serious cases which gives us a good clue that we must feed our colonies to avoid starvation. Otherwise the queen will reduce or stop egg laying which will create an imbalance in the colony and reduce chances of a second late summer harvest.

Where Do Beekeepers Find Information?

Next week I’ll be exploring beekeeping education and training but I’m curious to know how people decide where to go for accurate information? There is so much information out there and the knowledge and accuracy varies enormously between sources. I like to use a few blogs but I only pay attention to those whose writers have recognised beekeeping/scientific qualifications or who write regularily for beekeeping magazines. My favourite bloggers are Rusty Burlew, Randy Oliver and David Evans. Unsurprisingly, they appear high in the top 80 beekeeping blog charts. The Beelistener, a relative new kid on the block, has made it into the top 50.

Top 80 Beekeeping Blogs, Websites & Influencers in 2021 (

7 thoughts on “How to Recognise a Nectar Flow.”

  1. Fascinating, Ann, Yes the top fruit blossom started to open on Tuesday here, but it hasn’t rained for weeks. Yesterday the bees were defensive when John was gardening, so maybe they are short of nectar too. I shall investigate. Thank you for all the useful information. xx

  2. As a gardener by profession as well as a beekeeper this is an aggravating an aggravating spring. That said for the last dozen or years there have been a series of wettest or driest, coldest or hottest scattered through all the seasons. Poor bees.

  3. Good to hear that you are counting varroa (always a good conversation-piece at socially distanced meetings!). Are you spotting any uncapped worker brood at the white to pink eyed stage? Or white pupae exoskeleton bits on the varroa board? Both a sure-fire indication that your bees have the right “varroa intolerant” genetics in place.

    Similar-ish chilly spring weather here on the Surrey/Kent borders. Most colonies are 1-2 brood frames behind where they have been in a typical April. Sensible response by the bees to the lower nectar availability, though hedgerows are full of blackthorn and hawthorn.

    1. Interesting to hear that you are way behind in the south as well. I have not checked the colonies other than a very brief first inspection. My plan is to leave for a couple of weeks to let them build up as they are nowhere near strong enough to swarm yet. I will look closely though for uncapped worker brood at the white to pink eyed stage. I am seeing chewed out pupae under one colony so that is promising.

  4. Hello Ann

    I was interested to see the ‘Top 80 beekeeping blogs…’ but very disappointed in the list. Rusty Burlew as no. 1 I can accept. But so many others are missing and many others are just commercial operations. So it means nothing that you are not rated higher! Despite the claim by that the selection is by humans, to me this looks like the work of algorithms – though I’m no expert.

    I share the same favourite bloggers as you. Here are some others that I admire and enjoy: Janet Wilson Walrus (Steve Donohoe) Mrs Apis Mellifera (Emma Maund) Sustainable beekeping (Jennifer Moore)

    Women seem to manage better at this lark, at least IMO!

    Enjoyed this week’s post on nectar. Very much on my mind these days with this challenging weather!

    1. Hello Archie, I am sure you are right. Some may even pay to be listed so it is debatable really the value of being listed. Thank you for sharing your favourites with us. Glad you liked the nectar post. Still none coming in, and this week is very wet though the air temperature is rising. Ann.

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