  We study spherically symmetric gravitational collapse in cubic Horndeski
theories of gravity. By varying the coupling constants and the initial
amplitude of the scalar field, we determine the region in the space of
couplings and amplitudes for which it is possible to construct global solutions
to the Horndeski theories. Furthermore, we identify the regime of validity of
effective field theory as the sub-region for which a certain weak field
condition remains small at all times. We evolve the initial data using the CCZ4
formulation of the Einstein equations and horizon penetrating coordinates
without assuming spherical symmetry.
