Answer: The most common cause of premature fruit drop is incomplete or lack of pollination. This can happen if the tree is growing indoors (or was indoors at the nursery or greenhouse when the tree was in bloom). Since you're here in the PNW, I expect you're growing your tree indoors, or will be taking it indoors in the fall when the temperatures cool. If it's outside now and flowering, pollinating insects will find the flowers and transfer pollen. If it's indoors, you can help things along by visiting the flowers with an artist's paintbrush. There's no particular method to use - just gently brush the insides of all the open flowers. You'll know you've been successful if after the petals fall you see a tiny fruit.
There are other causes for dropping fruit - water stress or a change in temperature or even lack of sunlight. Be sure to keep the soil evenly moist. Water thoroughly then allow the top half-inch to dry out before watering again. Although lemon trees are well adapted to growing indoors, they still appreciate a few hours of sunshine during the summer months.
Hope this information is helpful!
p.s. I appreciate the thought but I make it a rule never to mix business with pleasure.
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