Growth stages table

Dormant or tight bud

Bud swell

Early green tip

Tight bud

Budswell

Early green tip

Plant part: Flower bud. Description: No visible swelling of the fruit buds. Bud scales tightly closed. No visible signs of   growth.

Plant part: Flower bud. Description: First sign of   growth as plant growth begins in the spring. Visible swelling of the flower buds; outer bud scales begin to separate at the tip revealing paler interior bud scales. This bud stage can usually tolerate cold temperatures of 10 to 15⁰F (-12 to -9⁰C).

Plant part: Leaf bud. Description: Bud scales are   separating at leaf bud tips. Green leaf tissue is emerging from the leaf bud tips. From 1/16 to 3/16 inch (2 to 5 mm) of green tissue is exposed. Leaves are tightly rolled.

Bud break or bud burst

Late green tip

Tight cluster

Bud break

Late green tip

Tight cluster

Plant part: Flower bud. Description: Flower buds open   and the individual flowers can be seen between the bud scales. Can tolerate cold temperatures of about 20⁰F (-7⁰C).

Plant part: Leaf bud. Description: Leaves are   beginning to unfold. More green leaf tissue is visible, ¼ to ½ inch (6 – 13 mm). This stage generally occurs around flower bud burst.

Plant part: Flower. Description: Individual flowers are distinguishable in the flower cluster. This bud stage can tolerate 20 to 23⁰F (-7 to -5⁰C).

Shoot expansion

Early pink bud

Late pink bud

Shoot expansion

Early pink bud

Late pink bud

Plant part: Shoot expansion. Description: Multiple leaves have emerged from the vegetative buds and unfolded. Leaves are enlarging and shoot growth has begun.

Plant part: Flower. Description: Expanding flowers are readily visible and have separated. The pink corolla tubes (petals) are short and closed. This bud stage can tolerate 23 to 25⁰F (-5 to -4⁰C).

Plant part: Flower. Description: Individual flowers fully developed. Expanded corollas are now white but still closed. This bud stage can tolerate 24 to 27⁰F (-4.4 to -2.8⁰C).

Early bloom

Full bloom

Petal fall

Early bloom

Full bloom

Petal fall

Plant part: Flower. Description: Some of the corollas are completely expanded and open. Many flowers are still closed. The bloom stages can tolerate 25 to 28⁰F (-4 to -2.2⁰C).

Plant part: Flower. Description: Most of the flowers on the bush have opened. The bloom stages can tolerate 28⁰ F (-2.2⁰C).


Plant part: Flower. Description: The corolla tubes are falling off the flowers, revealing small green fruit. This is the most vulnerable stage to freeze injury. Damage can occur at 32⁰F (0⁰C).

Early green fruit

Late green fruit

Shoot tip set; end of shoot growth

Early green fruit

Late green fruit

Shoot tip set

Plant part: Flower. Description: Small green berries are expanding. Fruit in the cluster varies from large to small pea-sized. Early fruit growth is by cell division.

Plant part: Fruit. Description: Growth of large fruit slows. Fruit becomes pale green. Exposed fruit may develop a red blush.

Plant part: Shoot. Description: Shoot tips die and shoot growth stops. No new small leaves can be seen emerging from the   shoot tip. The dead shoot tip may be visible as a small dead leaf at the base of the last leaf on the shoot. In Michigan, there is typically one flush of   growth in the spring, which ends before harvest. After harvest, some shoots will start growing again, for a second or third growth flush. These later growth flushes usually occur with moist soil conditions and moderate temperatures.

Fruit coloring

10% Blue

25% Blue

Fruit coloring

10 percent blue

25 percent blue

Plant part: Fruit. Description: Oldest, largest fruit in the cluster begin to change color from green to pink to blue. Fruit begins to soften. Cell division has stopped and fruit growth is by cell expansion.

Plant part: Fruit. Description: Single berries in the fruit clusters are ripe and ready to harvest. About ten percent of the fruits, on a bush or in the field, are ready to harvest. This stage is often used to begin the preharvest fungicides for fruit rots.

Plant part: Fruit. Description: 25 percent of the berries are ripe. 25% blue often coincides with first hand harvest of ripe berries.

75% Blue

Fruit bud set

Fall color

75 percent blue

Fruit bud set

Fall color change

Plant part: Fruit. Description: Blueberries are picked several times as the fruit ripens with 2 to 5 pickings. Often the first harvest is by hand and then later by machines that shake berries off the bush. 75% blue often coincides with the first of 2 machine harvests in the field.

Plant part: Shoot. Description: After harvest the blueberry bush stores reserves for next year’s growth. Shoot growth may begin again. Flower buds for next year’s crop form in September and October. These flower buds form first at the shoot tips. These large, clearly visible buds can be used to estimate next year’s crop potential.

Plant part: Shoot. Description: At the end of the growing season, the leaves change color as nutrients are mobilized back into the shoots for growth next spring.