You have a window and a ledge. That is a garden. Here is what to put on it.
First, figure out your window. Stand at it around noon. If the sun is on your face, that is direct light. If the room is bright but the sun is not on you, that is bright indirect. If you are squinting at your phone, that is low light. Each one grows something.
Direct sun, south or west facing
This is the jackpot. Poppies, herbs, chillies, anything that flowers. Start with a packet of poppy seeds in a 5 inch pot. Scatter on top of the soil, mist daily, and you will have seedlings in two weeks and flowers in about ten.
Bright but indirect, east facing or a bit back from the glass
Most houseplants live here. Pothos, peace lily, a small fern. Also lettuce and soft herbs like parsley and chives, which do not need as much sun as you think. Leafy things are forgiving. Flowers less so.
Low light, north facing or a shaded street
Still a garden. Snake plant, ZZ plant, a cast iron plant. They grow slowly and ask for almost nothing, which is a feature. Water every two to three weeks. Do not feel bad that you are not growing flowers here. Put the poppies on a brighter sill.
Three rules for any windowsill
Use a pot with a drainage hole and a saucer. Rotate the pot each week so the plant does not lean. Keep leaves off cold glass in winter. That is all of it.
Start with one pot. When it is alive in a month, get a second.
Get dirty.
