By Rabbi Dovid Ostroff
Because of the joy one has upon seeing or eating new seasonal fruit, Chazal instituted that shehechiyanu should be recited when this occurs.  Although some authorities hold that one should recite the blessing when seeing the new fruit, custom is that one recites it when eating the new fruit for the first time in the season. 
What if one forgets to recite the b’racha the first time?
Indeed it should be recited together with the b’racha on the fruit, i.e. before eating, but if one is still busy eating one may still recite shehechiyanu. If, for example, one is about to consume three apricots for the first time in the season, one should recite shehechiyanu prior to eating. If one forgot, one may recite as long as one is still eating the apricots. This is because one has simcha at that initial eating. If one forgets, then the next time around one may not recite shehechiyanu. 
What does one recite first, the b’racha on the fruit or shehechiyanu?
The P’ri Megadim and Oruch Hashulchan  prefer that one first recites shehechiyanu and then the b’racha on the fruit. This is to avoid making a hefsek (break) between the b’racha on the fruit and the eating. The Mishna Berura  also prefers this position.
The Be’er Heitev  and others say that one first recites the b’racha on the fruit and then shehechiyanu, and indeed many have that custom.
If several new fruit are on the table, does one recite a separate b’racha for each one?
So as not to recite an unnecessary b’racha , one should only recite one b’racha on all the fruit, even if one is not eating all of them at that sitting. This is also based on the opinions who say that one recites shehechiyanu upon seeing the fruit, so since one is reciting shehechiyanu when eating one or more of the fruit on the table, one should have in mind that the b’racha applies to all the fruit. 
What qualifies as seasonal fruit?
Fruits that appear once or twice a year.  One will recite shehechiyanu when eating new fruit from both seasons, because after all the fruit is seasonal. Fruit that is in stores all year round will not merit shehechiyanu.
Seasonal fruit kept in storage all year round will not merit shehechiyanu, unless the new fruit is different in taste or appearance. Fresh oranges are usually much tastier then oranges kept in cold storage.
Likewise, peaches and apricots etc. are seasonal even though one can obtain those canned fruit all year round.
If one frequents a place where there is fruit one has never tasted, does one recite shehechiyanu?
It seems not, because the b’racha was not instituted for personal reasons, rather upon seeing or consuming seasonal fruits, i.e. fruits that do not appear all year round and one has simcha when seeing or eating them. 
Does one recite shehechiyanu on p’ri ha’adamah?
Seasonal vegetables merit shehechiyanu, however many poskim write that one will not recite shehechiyanu on vegetables that are not “important” and do not bring simcha. 
One will recite shehechiyanu on watermelons, melons, bananas etc. even though the b’racha for them is ha’adamah, provided that they are seasonal in one’s location.
Does one recite shehechiyanu on different types of citrus fruit?
Boruch Hashem we are blessed with many types of citrus fruits and many want to know whether each one is different with regards to shehechiyanu. Since each one has a distinct taste, the rule is that one recites a shehechiyanu on each type, but as stated, when possible, one consolidates several types with one shehechiyanu when they are together.
Consequently, grapefruit, orange, tangerine, pomelo, kumquat etc. all merit shehechiyanu when seasonal and the stipulations are met. 
What about different types of apples?
The same issue applies to apples and the many types of mandarins. One does not recite a shehechiyanu for each type, because the difference is not that discernible and one has less simcha from the appearance of a different type. 
Does one recite shehechiyanu on unripe fruit?
Shehechiyanu is not recited unless the fruit is fully ripe. One must therefore take caution at the beginning of a new season and make sure that the fruit is fully edible and ripe before reciting shehechiyanu. 
 M”B siman 225:10.
 Siman 225:3.
 See åæàú äáøëä ôé”ç.
 Siman 225:5, adding that this is his custom.
 M”B siman 225:11.
 Siman 225:6.
 åæàú äáøëä ôé”ç based on àâ”î ç”à ñé’ ôæ.
 Siman 225:6 and Rama.
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 See åæàú äáøëä ôé”ç.
 See åæàú äáøëä ôé”ç.
 See M”B 225:12.