You can make your own plant-based organic fertilizer using common weeds and perennials!
The below are some common weeds growing in my zone 3, Alberta garden that can be used to make fertilizer:
Collect any of the above and chop or break up and add to a jar or bucket. Add distilled or rain water to the container, ensuring all the plant matter is covered. A rock can be used to weigh down the plants. I like to add a few tablespoons of cane sugar to the mix as well.
Let sit out for 3-7 days. It's best to do this outside as it can be quite smelly when the plants ferment and break down.
When completed, strain out the decomposed plant matter and throw into your compost bin. Keep the liquid in a sealed container. Use 1 part 'weed tea' to 10 parts water. I use as a soil drench or foliar feed on houseplants and out in the garden. Mature outdoors plants can tolerate a stronger dilution of 1 part 'weed tea' to 4 parts water.