HORTICULTURE

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CRITICAL SPRING TEMPERATURES FOR FRUIT BUD DEVELOPMENT STAGES

Apples Silver Tip is after the bud has started to open and before green tissue is exposed. Green Tip has green tissue showing at the bud tip Half inch green tissue showing The flower sare visible as a tight clutser of buds surrounded by leaves The colored petals are exposed Full Pink is before the petals open The King bloom is the first flower in the cluster to open most of the flowers on the tree are open aplpblm.jpg (2146 bytes) 
Apples
 
Silver
tip
 
Green
Tip
 
½ inch
green
 
Tight
Cluster
 
First
Pink
 
Full
Pink
 
First
Bloom
 
Full
Bloom
 
Post 
Bloom
 
Old temp
10% kill
90% kill
 
16
15
 2
 
16
18
10
 
22
23
15
 
27
27
21
 
27
28
24
 
28
28
25
 
28
28
25
 
29
28
25
 
29
28
25
 
 

Pears

 Swollen Bud in Pear with bud scales separating Blossom buds are exposed after bud burst Just before Tight Cluster The flowers are visible as a tight cluster of buds First white is when the cluster opens and the white of the petals show Full White or Popcorn is when the petals have expanded but the flower still isn't open When the first flowers open Full Bloom is when almost all the blossoms are open prpfs.jpg (15830 bytes) 
Pears
 
Bud scales
separating
 
Blossom
buds
exposed

 

 
Tight
cluster
 
First
White
 
Full
White
 
First
Bloom
 
Full
Bloom
 
Post
Bloom
 
Old temp
10% kill
90% kill
 
18
15
 0
 
23
20
 6

 

 
24
24
15
 
28
25
19
 
29
26
22
 
29
27
23
 
29
28
24
 
30
28
24
 
Apricots
 aprctbds.jpg (11338 bytes) The red calyx is visible after bud burst The red caylx is visible as the flower swells The white petals are easily visible First apricot flowers open on the tree Apricot at Full Bloom is when almost all the flowers are open. Apricot In the Shuck Small green apricots   
Apricots
 
Swollen
Bud
 
Tips
separate
 
Calyx
red
 
First
White
 
First
Bloom
 
Full
Bloom
 
In the
shuck
 
Green
Fruit

 

 
Old temp
10% kill
90% kill
 
--
15
--
 
23
20
 0
 
--
22
 9
 
25
24
14
 
--
25
19
 
28
27
22
 
--
27
24
 
31
28
25

 
 

Peaches
 BudSwell, when the bud first opens Green Caylx is when green color shows in the bud. The red color of the sepals is clearly visible The sepals have opened and the pink petals are visible The first flowers begin to open Most of the flowers have opened Peach In the Shuck     
Peaches
 
Swollen
Bud
 
Calyx
Green
 
Calyx
Red
 
First
Pink
 
First
Bloom
 
Full
Bloom
 
Post
Bloom

 

 

 
Old temp
10% kill
90% kill
 
23
18
 1
 
--
21
 5
 
--
23
 9
 
25
25
15
 
--
26
21
 
27
27
24
 
30
28
25

 

 
 
European
Plums
 At bud swell the buds are colorful and visibly larger. The sides of the buds are white. Green tip has green tissue visible at the tip of the bud Tight cluster is at and following bud burst As the clusters open the white of the petals is visible When the first flowers open in the cluster Full Bloom is when most of the flowers are open. plmpblm.jpg (12133 bytes)   
European
Plums
 
First
Swelling
 
Side
White
 
Tip
Green
 
Tight
Cluster
 
First
White
 
First
Bloom
 
Full
Bloom
 
Post
Bloom

 

 
Old temp
10% kill
90% kill
 
--
14
 0
 
--
17
 3
 
--
20
 7
 
--
24
16
 
23
26
22
 
27
27
23
 
27
28
23
 
30
28
23

 
 
Sweet
Cherries
 swtchell.jpg (11635 bytes) A lots of green color but bud hasn't opened yet   Sweet Cherries at white bud: Paw Paw, April 4   scewbud.jpg (10714 bytes) The first flowers open All the flowers are open   
Sweet
Cherries
 
Swollen
Bud
 
Side
Green
 
Green
Tip
 
Tight
Cluster
 
Open
Cluster
 
First
White
 
First
Bloom
 
Full
Bloom
 
Post
Bloom
 
Old temp
10% kill
90% kill
 
23
17
 5
 
23
22
 9
 
25
25
14
 
28
26
17
 
28
27
21
 
29
27
24
 
29
28
25
 
29
28
25
 
30
28
25
 
Tart
Cherries
 Swollen Bud, when the buds are noticably swollen Green Side is when green color is visible at the base of the bud scales When the tip of the bud is rounded and green At Tight Cluster you can see the individual flowers in the bud. The flowers have pushed out of the bud The white of the petals is visible The first flowers on the tree open Full Bloom is when most of the flowers are open tcshuck.jpg (11359 bytes)

Tart
Cherries

Swollen
Bud

Side
Green

Green
Tip

Tight
Cluster

Open
Cluster

First
White

First
Bloom

Full
Bloom

 

10% kill
90% kill

15
0

24
10

26
22

26
24

28
24

28
24

28
24

28
24

 
 

Concord
Grapes

 

Early Swell - Doe skin

Late bud swell shows a hint of pink

Bud Burst is when the leaves at the tip of the bud start to separate

When one leaf is 90 degrees from the stem

When 2 leaves are 90 degrees from the stem

When 3 leaves are 90 degrees from the stem (This isn't a concord shoot).

 

 

Concord
Grapes

Dormant

First
Swell

Late
Swell

Bud
Burst

First
Leaf

Second
Leaf

Third
Leaf

Fourth
Leaf

 

10% kill
90% kill

varies

13
-3

21
10

25
16

27
21

28
22

28
26

28
27

 

 

 

 

 

 

 

 

 

 

 

Old standard temperature is the lowest temperature that can be endured for 30 minutes without damage.
This chart also shows the temperature that will kill 10 % and 90 % of normal fruit buds. 
These numbers were taken from Washington (WSU), Michigan (MSU) and North Carolina (NCS) Extension Bulletins. Apple - WSU EB0913, Pears - WSU EB0978, Sweet Cherries - WSU EB1128, Peaches - WSU EB0914, Apricots - WSU EB1240, Tart Cherries - MSU Research. Rpt. 220,
Portions of these buletins are posted at Gregg Lang's Fruit Bud Hardiness Page at the MSU Horticulture Department
Two others are posted on the web: Concord Grapes - WSU EB1615, Bluerries, NCS- HIL-201-E

For information on current SW Michigan Fruit Development see the Fruit Update.

For more information on freezing injury see my Frost Freeze Page

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Last modified: May 10, 2004