Answer: I think by spider flower you must mean Cleome hasslerana. This is an annual and must be planted each year. There are taller and shorter varieties as well as some color variations in the pink, pinkish-purple and white ranges. Many times they will self seed in the garden although when this is allowed they tend to all revert over the years to all the same pink or white.
Or you can collect seeds. They should be very dry and then stored in a cool dry place (such as in a paper envelope in a desk drawer, or in a closed jar in the refrigerator) until you are ready to plant them.
They do need to be chilled prior to planting. Some gardeners will sprinkle them on the last snows of March where they want them to grow. Other people palnt them in a seed pan of slightly dampened soilless planting mix, place it in a plastic bag, and chill it in the refrigerator for about a month. Then start as for any other annual flower seed. Most seed catalogs (and many nurseries in spring) offer seeds for Cleome. Some nurseries will also sell small transplants in the spring.
Lily of the Nile or Agapanthus would not winter hardy where you are, so you would need to grow it as a container plant and bring it indoors to a sheltered location each winter. Your local nurseries may carry it -- more likely in the spring than now in the fall -- or you may be able to order it by mail from specialty nurseries.
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