Weed killer: 1 gallon vinegar, 2 cups epsom salt, cup dish soap not sure how this is organic unless she uses organic vinegar, organic Epsom salt & organic dishsoap- which I don't think is possible but more or less chemical free.
Garden design by carolyn mullet: Plant stairs with succulents - this actually works very well, the succulents thrive on the heat from the stone in summer. If you periodically wash the stairs off with (Garden Step Gabion)
Baking soda neutralizes the ph in the soil and is a natural weed killer. Sprinkle baking soda around all of the edges of garden areas to keep the grass and weeds from growing into flower beds. Just lightly cover the soil twice a year – spring and fall.