When does mountain laurel bloom in New Jersey?

Most often in June. Across 253 dated, research-grade observations of Kalmia latifolia in New Jersey, the flowering season runs roughly June.

Peak June In flower 253 Examined 484 State New Jersey

Flowering 253 in flower of 484 examined

62%

94%

11%

Proportion of examined Kalmia latifolia in New Jersey in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	5	0%	0% to 43%
Feb	0	4	too few examined
Mar	0	5	0%	0% to 43%
Apr	1	48	2%	0% to 11%
May	154	250	62%	55% to 67%
Jun	95	101	94%	88% to 97%
Jul	2	18	11%	3% to 33%
Aug	0	10	0%	0% to 28%
Sep	0	12	0%	0% to 24%
Oct	1	13	8%	1% to 33%
Nov	0	6	0%	0% to 39%
Dec	0	12	0%	0% to 24%

Peak flowering in Jun. Each bar is the share of Kalmia latifolia in New Jersey 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. 253 of 484 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. One month has fewer than 5 examined observations, so no proportion is drawn for it. 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 New Jersey found Kalmia latifolia in flower, not a forecast. It is computed only from observations made in New Jersey, 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

Kalmia latifolia

mountain laurel

Sourcesevery claim on this page

GBIF (iNaturalist Research-grade Observations). Dated flowering annotations in New Jersey. 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.