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Sunday - February 15, 2009

From: TARRYTOWN, NY
Region: Northeast
Topic: Wildflowers
Title: Growing Lupinus perennis in sandy soil.
Answered by: Jimmy Mills

QUESTION:

I want to grow Lupinus perennis for the Karner butterfly. I know it won't grow in clay (my soil is wet clay). Can I plant the plant in a big (20" diameter x 17" tall) rubber pot, and fill the pot with sandbox sand. (Or some other kind of sand?) If so, how many can I put in that size container? thanks.

ANSWER:

Lupinus perennis (sundial lupine) is a beautiful plant that prefers to grow in well drained, sandy soil. However, "sandbox sand" is not what you want to use; the particle size is too small and it becomes compacted. You want something coarser that is commonly called "builder's sand", and you also need to add organic matter such as peat moss or leaf mold to provide nutrients and help hold moisture. Make sure that the pots you use allow for drainage.

The USDA Forest Service link has a lot of information about the Sundial Lupine and its growth requirements (be sure to scroll through the whole page), and the UMass Extension link tells about good soil mixtures to use.

The USDA link suggests that the Lupine seeds can be planted 5 per square foot. Since the area of your container is a little over two square feet, you should plant to have 10 or 12 about evenly spaced lupines in your pot. You will probably want to sow more seeds than that, since some will probably not germinate the first year.