Keep in mind when planting that Dwarf Houghtonii is thought of as tender, so remember to ensure that temperatures are mild before moving outdoors.
By our calculations, you should look at sowing Dwarf Houghtonii about 91 days before your last frost date.
As Dwarf Houghtonii is tender, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.