I've had a foxtail plant in my garden for a while now, and I've learned that they need quite a bit of direct sunlight to really thrive, so make sure it's getting at least 4-6 hours of sun a day. As for watering, foxtail plants prefer well-draining soil and can be susceptible to root rot if the soil is too moist, so I'd recommend watering sparingly, allowing the top inch of soil to dry out between waterings. Also, make sure your soil has good drainage, you can add some organic matter like compost to help with that, this should help your plant grow as expected.