Pollination isn’t as difficult a subject as most people think!
One of the most common questions asked of Grandpa and Grandma is about pollination! You wouldn’t think that something that is related to the bees and the birds would be so troublesome. Here is some basic info:
APPLES— Consider all apples as needing another DIFFERENT variety of apple to pollinate properly. Usually a good pollinator will bloom in somewhat the same timeframe in the spring, so early and midseason blooming apples go well together as well as mid-season and late blooming varieties. Don’t depend on an early season bloomer to pollinate a late season bloomer, or vice versa. Most ornamental crabs can be depended on to help pollinate also, so if there are lots in your neighborhood there is another good source of pollen. There is no set distance that one apple pollinator needs to be from another. The bees transfer a lot of the pollen between themselves in the hives, and then carry it back to different trees.
If you have 4 or more different apple varieties planted near each other, then you most likely will not have to worry too much about proper pollination and matching up bloom times. The more varieties you have, the better chances they are going to get pollinated well. Don’t be taken in by some of the “expert” advice that you “need” a pollinator crab apple— I think they are just trying to sell another tree. Commercial growers use crabs as a normal practice because they are planting thousands of trees of the SAME variety in large, solid blocks. They don’t usually “mix-up” varieties as much as they used to. So inter-mixing pollinator crabs in this case makes a lot of sense because the grower doesn’t have to worry about trying to care and harvest some other variety mixed in to the preferred variety.
Some varieties of apples are NOT good pollinators, and these same ones require other varieties to pollinate them. Usually they are “triploid” varieties (like Jonagold, Stayman, Winesap, Mutsu or Crispin, Rambo, and a few others). Because they have an extra set of chromosomes (3 not 2 sets— thus tri-ploid) their pollen is essentially sterile. In a few cases, some varieties are so closely related that their relatives shouldn’t be used to pollinate each other. The most common examples are Gala, Golden Delicious, and Jonagold, or the many “strains” of new varieties coming out that are actually the same basic variety, but differ mostly in color-factor, ripening time, etc.
PEARS— Pears are like apples. While some varieties are considered self-fertile and don’t absolutely have to have another pollinator, it is wise to have another DIFFERENT variety as a pollen source. Some varieties have sterile pollen and can’t be depended upon to pollinate other varieties. We always try to make note of sterility in the description, so don’t count them as a “different” variety or as a good pollen source. They will need a non-sterile variety to pollinate them too. Once again, if there are pears in the neighborhood, then you can likely depend on them somewhat to help a lot because of the bees transferring pollen in the hives.
PEACH & NECTARINE— With the exception of J.H. Hale peach, ALL peach and nectarine varieties are self-fertile and don’t need another different variety for pollination. While “foreign” pollen might help with larger fruit size according to some, the variety’s own pollen will do just fine. Plant one tree and you will almost always have too much fruit set. You will need to thin most of it off for good size fruit.
PLUMS, PRUNES & APRICOTS— It does get a little bit more complicated with these three types of fruit. To be safe, it is always best to have at least one other variety of the same type of fruit to help with pollination. Many European plums and prunes are considered self-fertile, but they will benefit by having another different European variety as another pollen source. Japanese plums are usually not self-fertile, so always have at least one or two other different varieties— the more the merrier! The same essentially goes for the “hybrid” plums. Many apricots are considered self-fertile, but experienced apricot growers feel that you should have other apricot varieties still to improve fruit set.
TART CHERRY— Many tart cherries are self-fertile, especially Montmorency, but some of the newer tart cherries like Danube, Jubileum and Balaton seem to set better with other tart cherry varieties. While tart cherry and sweet cherry can cross pollinate, don’t depend on them because usually they bloom at too different a time frame, and their pollen is usually only fertile and “hot” for a few day period. Since sweet cherry typically blooms well ahead of tart cherry, they may be genetically compatible, but their pollen may never be viable at the same time.
SWEET CHERRY— OK! This one is a tougher one! Sweet cherries in the old days always required a compatible pollinator that bloomed in a similar time-frame, as well as having the correct genetics! With the introduction of Stella, Lapins, and other self-fertile cherries, it has made sweet cherry pollination a simpler thing to explain, but still somewhat challenging. Grandpa’s Orchard always tries to tell you if a sweet cherry is self-fertile. These self-fertile varieties can be planted as a single tree, without a neighbor and set fruit. They also make good pollinators for those many older varieties that require a compatible pollinator. Still, it is important to try to have compatible pollen sources which bloom in similar time frames so that the short-lived cherry pollen is still viable when the bees transport it around. The key to all this confusion is having the proper set of genes to make one variety compatible with another. The self-fertile sweet cherries have the right genetics to do a better job of setting a good crop with all other sweet cherry varieties.
I hope this helps with the confusion, but I know that it will still be the one single subject that we get the most questions asked about. I guess this is why there are some PHD’s in the business who can specialize in this type of knowledge. An old generalist like Grandpa may not have ALL the answers, but the old dog knows some pretty good tricks of the trade!