Coast tarweed is in the sunflower family (Asteraceae). It's an annual herb that grows to be 12 to 24 inches high. It blooms from mid-summer to early fall, with flowers that are chartreuse (greenish-yellow) in color. They resemble sunflowers, but are smaller in size. The stems are stiff with many leaves. Both the leaves and the stems have sticky hairs. Coast tarweed can be added to your garden using seeds, which germinate rapidly. Plant the seeds in the fall.
Choose a well-drained planting area that has fairly dry soil and sits in the full sun. Dry soil types have more sand in them than clay because sand is low in organic matter and tends to drain water away quickly. Make sure there isn't any potential for standing water.
Use hand tools to loosen up the top layer of soil. Place the seeds on the soil surface or 1/8 inch to 1/4 inch deep.
Cover the seeds with a thin layer of soil, then water. As seedlings sprout, water them every two or three days to stimulate growth. Touch the soil with a finger; if it's not moist, add water.
Use a liquid fertilizer to encourage seed production and growth. Apply the fertilizer every two to three weeks. Most fertilizers come in concentrated form, so mix it with water using a watering can or hose-end sprayer. Follow the manufacturer's instructions for mixing fertilizer.
Deadhead the flowers (remove them once they die) to keep the self-sowing at a minimum, if you want a more controlled growth pattern. Expect the coast tarweed to spread and be invasive. It drops seeds that then create new seedlings next season.