Nectar flow calendar for Dutch beekeepers: what blooms when and what do you do then?
The difference between a good beekeeping year and a bad one rarely lies in luck. It lies in timing.
Whoever knows what nectar flow is coming places the honey super at the right moment, extracts before the next bloom, and notices four weeks earlier that a colony needs extra space. Whoever does not, runs after the bus and harvests less.
In this article I list per month what blooms in the Netherlands, what you do as a beekeeper, and what the pitfalls are. Important note in advance: nectar flow is regional. What starts in March in Limburg may only start in May in Groningen. The Veluwe has heather, the Betuwe has fruit blossom. The numbers below are averages for the central Netherlands. Build your own local calendar on top, because that is what ultimately matters.
January - rest for the colony, thinking work for the beekeeper
What blooms: practically nothing. On the very warmest days the first snowdrops may appear in the garden.
What you do as a beekeeper: little to the hive. But: order protective clothing, check tools, think about the coming season. Read, attend course evenings.
Tip: walk past your apiary site this month and count how many hives you can fit there next season. Plan for one more than you have now. Swarms are coming.
February - first signs
What blooms: hazel (mainly pollen), corydalis, lesser celandine, the first crocuses. On mild days you see bees flying out for pollen.
What you do as a beekeeper: quick external check. Does the lid sound hollow or heavy when tapped? Weight tells you whether there is still food. Do not open the hive yet, except in real emergencies.
Tip: if you doubt food stores, place a fondant cake (or sugar paste) on the frames. Safer than liquid food in this cold month.
March - spring start
What blooms: willow catkins (Salix) are the most important early pollen source in the Netherlands. Plus hazel (declining), crocus, snowdrop, daffodils.
What you do as a beekeeper: first real spring inspection once it is structurally above 12C and dry. Check:
- Is the queen laying? (eggs visible)
- How much brood is there?
- Enough food still?
- No disease signals?
Tip: if you have a willow nearby, stand by it on a sunny March day. The buzzing tells you how strong your colony is. Busy entrance = strong colony. Silence = worries.
April - real work begins
What blooms: dandelion (Taraxacum) is the spring party for bees. Plus fruit blossom (pear, cherry, apple) in fruit-growing regions, maple, dogwood, blackthorn, coltsfoot. The verges and meadows turn yellow.
What you do as a beekeeper:
- Weekly inspection if the colony is strong
- Place first honey super (preferably with drawn-out frames)
- Start queen-cell checks from late April
- Have reserve equipment ready for swarm catching
Tip: place your honey super slightly earlier than you think you need to. Too much room is no problem, too little means they will swarm. A strong April colony given no space will swarm.
May - the busiest beekeeping month
What blooms: dandelion still abundantly. Hawthorn (Crataegus), white dead-nettle, first clover, maple finishing. Garden plants like lavender start.
What you do as a beekeeper: weekly inspection. Queen-cell checks are not optional. May is the swarm month. For strong colonies: split or remove drone brood. Watch the rainfall, because clover needs rain plus sun to give nectar.
Tip: note in a notebook when what blooms in your area. After three years you have a calendar that fits your stand, and that is worth more than any standard overview.
June - summer breaks loose
What blooms: white clover (Trifolium repens) is in June the most important nectar source in the Netherlands. Plus linden begins (early lindens), brambles, phacelia (often sown), purple dead-nettle, chestnut, robinia in some regions (acacia honey!), wild rowan.
What you do as a beekeeper: swarming urge declines around mid-June. Summer management: extra honey super, queen cells still checked, first honey harvest preparation in linden regions.
Tip: if you live in an area with many lindens (Utrecht city, old avenues, parks), June is the moment for your biggest harvest. Linden gives sometimes 5-10 kg per hive in two weeks under ideal weather.
July - harvesting and switching
What blooms: linden still (July is peak for late lindens). Clover, brambles, thistle starts, some agricultural crops (rapeseed second bloom, sunflower in the south), thyme.
What you do as a beekeeper:
- Honey harvest (summer honey, often early to mid-July)
- Extracting, sieving, jarring
- Right after harvest: start varroa treatment (thymol or formic acid)
- No honey super back during varroa treatment
Tip: wait with extracting until more than two-thirds of cells are capped. Unripe honey with too much water will ferment in the jar.
August - heather and first rest
What blooms: heather (Calluna) on the Veluwe, in Drenthe and Brabant heather areas. For travelling beekeepers this is the moment for heather honey. Plus field thistle, Himalayan balsam (controversial: invasive, but bees love it), late clover, bean fields.
What you do as a beekeeper:
- Varroa treatment must finish around mid or late August
- Start thinking about winter feeding
- Heather harvest in last week of August (in heather areas)
- Colonies are now physically at their weakest: older bees die faster than winter bees are born
Tip: a strong colony in August is gold. A weak colony in August rarely survives winter. Be honest about that and unite weak colonies with strong ones before you start feeding.
September - feeding and preparing
What blooms: ivy (Hedera) is the most important late bloomer. For the bees themselves, not for your harvest. Gives the colony a final boost of pollen and nectar. Plus autumn aster, sedum, dahlia.
What you do as a beekeeper:
- Winter feeding, 12-15 kg sugar water per colony
- Second mite count to check varroa treatment effect
- Reduce entrance against wasps and mice
- Final winter location is the same as summer (unless you move)
Tip: feed in two or three portions with a week between. Once dumping 15 litres of sugar water on the hive is too much for the colony to process without damaging brood.
October - last flights
What blooms: ivy declines, here and there still late autumn aster. Bees fly on sunny days for the last odds and ends.
What you do as a beekeeper:
- Finish feeding (end of October ideally done)
- Place mouse guard
- Keep mantle flap closed against moisture
- Last varroa count
Tip: walk past all hives once, lift them. Too light? Feed. Too heavy is no problem, too light is a dead colony in March.
November - winter preparation done
What blooms: nothing significant anymore.
What you do as a beekeeper: practically nothing. Colony forms winter cluster around 8-10C. No more opening, no more disturbing. Once a week briefly past.
Tip: check there are no leaves or branches in front of the entrance. A blocked entrance in November costs you a colony in January.
December - oxalic acid and silence
What blooms: nothing.
What you do as a beekeeper:
- Oxalic acid treatment in the broodless period (often early December)
- Otherwise rest for the colony
- Time for yourself: read, take a course, plan next season
Tip: note at the end of the year what went wrong that year. Which colony lost? Why? Which month did you run behind the facts? That writes 80 percent of beekeeping wisdom in a few lines.
Personal seasonal experience: May is for me every year the most beautiful month. Nicely into the bees every week, calculating, looking, searching for queen cells, looking for the queen, maybe a little honey already? Wonderful. As far as I am concerned this month may last half a year. As for the other extremes: November can go for me, but then you arrive at January earlier afterwards.
How do you keep your own nectar calendar?
My suggestion: a cheap notebook, one page per month, three years long. Write down:
- Which plants you saw blooming
- Which date you saw the first dandelion
- When the linden turned yellow
- When the heather coloured
- How your colony was doing
After three years you have a regionally-specific nectar calendar. A local willow blooms earlier than the willow on the Veluwe. Those kinds of details determine your harvest.
Honestly: I do it mostly by feel myself. But there is one rhyme from the old days that has never let me go:
"Als de paardenbloem gaat pluizen, dan gaat de koningin verhuizen." ("When the dandelion goes to seed, the queen will move on.")
That is actually the moment swarming season really begins. No calendar needed, no app, no technology. One flower going to seed, and you know what is coming. To me those kinds of old rules are at least as valuable as a spreadsheet full of bloom dates. They have helped generations of beekeepers through May.
The top 10 most important nectar plants in the Netherlands
Not scientifically ranked, but based on what most Dutch beekeepers would confirm:
1.White clover - most general summer flow
2.Linden - high quality, concentrated peak (June-July)
3.Dandelion - first real spring flow
4.Heather - regional top flow, unique flavour
5.Willow - early pollen, but not for honey
6.Fruit blossom - regional in fruit areas
7.Ivy - important for the colony, not for you
8.Phacelia - often sown, reliable
9.Brambles - long bloom, decent nectar
10.Maple - underestimated, early source
Finally
A nectar calendar is a reading guide. A prediction, not a guarantee. The weather, the rain, the sun, the wind, everything plays a role. But if you know what is coming, you are prepared.
Got an important regional nectar source I missed? Or your own rhyme or rule from your area? Post it in the forum, in Plants & Nectar Flow. There we build a Dutch nectar map per province together.
Good flow ahead.