Fertile or Fallow

1st-level necromancy (ritual)

Casting Time: 5 minutes

Range: Touch

Components: V, S, M (flowering or seeding branch or fruit)

Duration: One lunar month

For the duration of the spell, the target either becomes extremely fertile or completely infertile. An unwilling target gains a Constitution saving throw to resist the effect. Note that this spell cannot produce fertility where compatibility is impossible, such as in a pairing of a human and an elf, but otherwise—if cast to increase fertility—all but guarantees pregnancy, seeding, or budding at the next opportunity.

You can use this spell on animals or plants as well as people, and in fact its most common usage is to increase food production.