When does twinberry honeysuckle bloom in California?

Most often in April. Across 771 dated, research-grade observations of Lonicera involucrata in California, the flowering season runs roughly January to December.

Peak April In flower 771 Examined 1,229 State California

Flowering 771 in flower of 1,229 examined

86%

79%

91%

94%

60%

46%

35%

36%

31%

25%

44%

88%

Proportion of examined Lonicera involucrata in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	19	22	86%	67% to 95%
Feb	46	58	79%	67% to 88%
Mar	166	183	91%	86% to 94%
Apr	218	233	94%	90% to 96%
May	99	166	60%	52% to 67%
Jun	91	198	46%	39% to 53%
Jul	55	155	35%	28% to 43%
Aug	37	103	36%	27% to 46%
Sep	21	67	31%	22% to 43%
Oct	5	20	25%	11% to 47%
Nov	7	16	44%	23% to 67%
Dec	7	8	88%	53% to 98%

Peak flowering in Apr. Each bar is the share of Lonicera involucrata in California observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 771 of 1,229 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.wt38fd.

What this is, and what it is not

This is a record of when people in California found Lonicera involucrata in flower, not a forecast. It is computed only from observations made in California, so it is not the species’ global average dragged onto a map: the same plant flowers on different dates in different places, and that is the entire point of the page.

It will not tell you what your particular plant will do this year. Bloom time moves with the season, with altitude, and with the weather, and a warm February pulls everything forward. We publish the distribution and the sample size, and we refuse to draw a month that too few people examined.

The plant

Lonicera involucrata

twinberry honeysuckle

Sourcesevery claim on this page

GBIF (iNaturalist Research-grade Observations). Dated flowering annotations in California. Every record achieved iNaturalist quality grade Research, which is applied upstream at export. 10.15468/dl.wt38fd. Retrieved 2026-07-14.
World Flora Online Plant List. The accepted name. CC0. Retrieved 2026-07-12.