Bay Trail Wildflowers
Field notes from the East Bay

Bloom calendar

Ranges below are the middle eighty per cent of our recorded first-bloom and last-bloom dates. In any given year expect to be a fortnight either side.

Late winter

Milkmaids are the reliable opener — creamy, four-petalled, in leaf litter under oaks from the second week of January in a mild year. Manzanita is often already finishing by the time anyone notices it started. This is the quietest and, for our money, the most pleasant time to walk: no crowds, and the hills are as green as they get.

SpeciesTypical rangeWhere
MilkmaidsEarly Jan – mid MarOak shade, north slopes
ManzanitaDec – FebRidge chaparral
Shooting starLate Jan – MarDamp grassland
ButtercupFeb – AprOpen grassland

Spring

The main event, and the reason most people come. Poppies open on the warmer slopes first and can carry on for two months if the rain keeps up. Lupine follows a week or two behind and the two together account for most of the photographs ever taken of these hills.

Blue dicks and Ithuriel's spear come through the drying grass in April, when everything else at ground level is already going over. They are easy to miss because by then people have stopped looking down.

SpeciesTypical rangeWhere
California poppyLate Feb – JunOpen slopes, roadsides
LupineMar – MayGrassland, disturbed ground
Blue dicksMar – MayGrassland
Indian paintbrushApr – JunGrassland edges
Chinese housesApr – MayShaded banks
MonkeyflowerMar – JulCreek corridors, seeps

April is when the hills change colour from green to gold, usually over about ten days. If you want photographs of green hills with flowers in them, do not leave it until the end of the month.

Summer

Inland, very little. The hills are dormant and walking them in July is a matter of tolerating heat for the sake of the view. The shoreline, though, is at its best — the marsh edge stays damp and gumplant flowers steadily through the hottest weeks. Fog helps.

SpeciesTypical rangeWhere
GumplantJun – OctMarsh edge, levees
Sea lavenderJul – SepSalt marsh
Alkali heathJun – SepSalt marsh
TarweedJul – OctDry grassland

Autumn

Tarweed carries the dry season alone until the first serious rain, at which point the grass greens up within a week and the whole cycle begins again. There is a short window in late October and November — after the rain, before the cold — when a few things flower briefly out of season. Nobody has satisfactorily explained this to us.

How these dates were compiled

Eleven years of walking records from seven regular contributors, covering roughly forty routes. Dates are recorded as first-seen and last-seen per route per season, then pooled. This method systematically records blooms slightly late — nobody walks every route every week — so treat the early end of each range as the more reliable figure.

The raw records are messy and inconsistently formatted, but if you have a use for them we are happy to share.