If thy are really spindly, maybe they aren't getting enough light. If they are indoors, you need strong artificial light of the right type.
Ok frist you must be collect 1st quality seeds. And the seeds groing percent is more than 75% then it's perfect for you.You can know about this subject to aggriculter fram or look like Youtube.
I am trying to grow some garden annuals, like zinnias, cardinal climber, and daisies from seed. When they germinate, the plants are skinny and spindly-looking. How can I get my seedlings to look like the flowers you buy in flats at Home Depot and Walmart.