<Patch>
    <!-- Using 'Append' explicitly is considered verbose here, yes. -->
    <Operation Class="PatchOperationAdd">
        <xpath>*/ThingDef[defName="Plant_Devilstrand"]/plant/sowTags</xpath>
        <order>Append</order>
        <value>
            <li>Hydroponic</li>
        </value>
    </Operation>
    <Operation Class="PatchOperationAdd">
        <xpath>*/ThingDef[defName="Plant_Corn"]/plant/sowTags</xpath>
        <order>Append</order>
        <value>
            <li>Hydroponic</li>
        </value>
    </Operation>
    <Operation Class="PatchOperationAdd">
        <xpath>*/ThingDef[defName="Plant_Haygrass"]/plant/sowTags</xpath>
        <order>Append</order>
        <value>
            <li>Hydroponic</li>
        </value>
    </Operation>
</Patch>