Virtually all apple trees (Malus domestica) need cross-pollination to produce fruit. The “Gravenstein” is no exception to this rule. Finding the right apple trees to pollinate another involves matching spaces, environments and bloom times. The “Granny Smith” apple tree is one of many options to consider, but has several characteristics which are not ideally matched to this “Gravenstein.”
Cross-Pollination
Nearly all kinds of apple trees have been self-sterile, meaning they are incapable of making fruit on their own. Cross-pollination with a different cultivar is vital to turn flowers into apples. Bees or other insects require pollen from one apple tree and move it to the stamen of the other nearby tree. The pollen fertilizes the blossom and also creates an apple, the product of reproduction.
“Gravenstein” Apples
“Gravenstein,” out of Denmark, are early-blooming trees which produce sweet-tart red and yellow apples. They can endure in a wide variety of environments. They’re considered to be a borderline low-chill apple, requiring 700 hours of chill in the winter to blossom, and so are familiar growing in U.S. Department of Agriculture plant hardiness zones 3 through 9. “Gravenstein” is completely infertile. Apples such as these are called triploids and both need a cross-pollinator and cannot pollinate different trees. This means you either need 2 pollinators — one to pollinate the “Gravenstein” and one to pollinate the pollinator — or alternatively a single pollinator that’s self-fertile.
“Granny Smith” Apples
“Granny Smith” are self-fertile apples which bloom late in the season. While the self-fertile aspect could make them appealing, the blossom time isn’t ideal for pollinating the early-blooming “Gravenstein.” For a pollinator to function, the blooms must be present at precisely the same period of this year therefore the pollen can be moved while in blossom. Because of this, the “Granny Smith” is not thought to be a fantastic choice for some “Gravenstein” pollination partner.
Good Pollinators
The very best choices for a single pollinator for your “Gravenstein” apple are self-fertilizing and ancient blooming. Two of the most harmonious self-fertile trees have been “Chehalis” and “Earligold.” “Chehalis” is a sweet dessert apple, while the “Earligold” is a tart variety. Both varieties grow in USDA zones 5 through 9, overlapping nicely together with the “Gravenstein’s” hardiness, and blossom early in the growing season. “Earligold” apples are green, while “Chehalis” are yellowish with a pink blush.