Choose the grafting point with an eye on how the branches will grow and the fruit will bear.
Literal
Branches [subject-が] grow-[ren'yōkei-び], fruit [subject-が] bear [thing-こと] [object-を] anticipate-[and-て] graft place [object-を] choose-[volitional-ましょう].
Gardening/horticulture instruction. 接ぐ ('to graft') is the horticultural term for joining two plants so they grow as one — a classic technique for fruit trees. 実が成る ('fruit forms/ripens') is the set collocation for fruiting, using the verb 成る ('to become, to form'). 想定する ('to anticipate, to suppose, to assume') is formal. 伸び uses 連用中止法 (ren'yōkei stem-linking) for a slightly written register.