Specify the step between major gridlines in a DateTime series

I've created an area chart, illustrating the status of many media players throughout a single day. The data has a granularity of one minute.

I want there to be a major gridline at every hour, and a minor gridline at every half hour. I cannot see where you can set the "step" of the grid line.

Here's how I'm currently setting it up:

$("#chart").kendoChart({
    theme: "blueOpal",
    title: {
        visible:false
    },
    chartArea: {
        height: 800
    },
    legend: {
        position: "bottom"
    },
    seriesDefaults: {
        type: "area",
        stack: true
    },
    series: [],
    valueAxis: {
        labels: {
            format: "{0}",
            visible: true
        }
    },
    categoryAxis: {
        categories: [],
        labels: {
            visible: true,
            step:60
        },
        minorGridLines: {
            visible: false
        },
        majorGridLines: {
            visible: true,
        },
        majorTicks: {
            visible: false,
            size: 2
        }
    },
    tooltip: {
        visible: true,
        format: "{0}"
    },
    seriesColors: [
            '#336699',
            '#EBAD60',
            '#FF0000',
            '#9582BB',
            '#028482'
    ]
});

And it looks like the attached image. In this image there are so many lines that they stop serving a purpose.