Use grid-auto-rows (automatically generated rows) instead of grid-template-rows (manually generated rows). In current case grid-auto-rows: 150px will do the trick. Demo:
.grid {
display: grid;
grid-auto-rows: 150px;
/* space between columns for demo */
grid-gap: 10px;
}
/* just styles for demo */
.grid__item {
background-color: tomato;
color: white;
}<div class="grid">
<div class="grid__item">One</div>
<div class="grid__item">Two</div>
<div class="grid__item">Three</div>
<div class="grid__item">Four</div>
<div class="grid__item">Five</div>
<div class="grid__item">Six</div>
<div class="grid__item">Seven</div>
<div class="grid__item">Eight</div>
<div class="grid__item">Nine</div>
</div>