Blessing on lemons:
Lemons that are only mildly sour and are thus edible receive the blessing of Shehakol. Lemons that are very sour to the point of inedibility do not receive a blessing at all prior to consumption.
Lemon peel: The peel of a lemon which is edible receives the blessing of Shehakol prior to consumption.
 Ketzos Hashulchan 49/16; Brachos Guide in English Birchas Hanehnin; Brachos guide of Rav Prus; Seder Birchas Hanehnin 6/22 of Rav Elyashvili footnote 130; See Piskeiy Teshuvos 202/35 footnote 208 who states there are three types of lemons: a) Very sour and inedible-no blessing; b) Very sour but still edible-Shehakol. This is majority of lemons today; c) Mildly sour lemon-Haeitz according to Admur 205/1; d) Lemon juice with sugar is Haeitz is majority lemon juice; Vetzaruch Iyun Gadol on many of his points as a) Admur 205/1 never states that a food that can be eaten “Beshas Hadechak” receives its set blessing; b) Admur explicitly states in many places [see below] that we follow the intent of the planting if planted to eat in its current state; c) How does there exist these three types of lemons? d) How can one say Haeitz on a juice in direct contradiction to the ruling in Michaber 202/23! Obviously, one may not rely on his words at all regarding this matter, and the ruling remains as stated above!
 The reason: As these fruits are edible in a time of need and thus they receive a blessing. [See Admur 202/4; Seder 6/1; Ketzos Hashulchan ibid and 49/7] However, their blessing is Shehakol, as all fruits that are not commonly planted to be eaten in their current state, but rather for use of seasoning, receive the blessing of Shehakol. [Seder Birchas Hanehnin 6/22; Luach 9/9; Admur 203/6 and 204/3-4 and 205/1; M”A 203/4]
 See Admur 202/4; Seder 6/1; Ketzos Hashulchan ibid and 49/7; Michaber 202/2; Birchas Habayis 1/49; Piskeiy Teshuvos 202 footnote 96
 See Admur 202/9; Seder 6/4 and 15; Ketzos Hashulchan 51/7 footnote 7