Try sedum, hydrangeas or hostas under spruce evergreen

Q. In my yard I have a large spruce evergreen that is about 40 feet tall and has the bottom branches removed about 7 feet from the ground. I would like to plant some type of perennial at the base of the tree, but the soil has so much acid from the sap and pine needles. Nothing seems to grow. What do you recommend? I was wondering if some type of sedum would grow there.A. Yes, several types of sedum should grow in that area if it receives full sun or light shade. You might consider Gold Moss Sedum, also called Biting Stonecrop (Sedum acre.) This type of sedum needs well-drained acidic soil and prefers sandy or gravely soil. Sedums are very hardy and tolerate a variety of soil conditions. There are many types of sedum available; check at your local nursery to find a variety that will do well in your area.If the area is shady you can consider using azaleas, rhododendron, ferns, astilbe, lily-of-the-valley and hostas. Rhododendrons and azaleas do best when grown in an area protected from harsh and drying winter winds from the west and northwest. If you like hydrangeas and are interested in doing an experiment you could plant a hydrangea under the tree and see what affect the acidic soil has on the flower color. Typically adding acid to the soil will result in flowers tending toward blue and purple. If the area is shady, choose an Oakleaf-type hydrangea that will bloom in full shade.Q. I am getting ready to move my houseplants outdoors for the summer. I have most of them in clay pots and noticed that over the winter a white crystal-like substance collected on the outside and bottom of the pots. Where is this substance coming from and does it harm the plants? How can I remove it?A. The white crystalline material on the pots is probably a combination of salts from fertilizers and calcium carbonate/calcite (CaCO3) from the water you use on the plants. The clay pots are porous and absorb the fertilizer/water solution you add to the pots. When the water evaporates you have the remaining white salt deposits from the fertilizer and calcite from "hard water." These deposits are cosmetic and should not harm the plants unless you over-fertilize the plants.Remove the deposits by wiping the pots with a rag soaked with vinegar; scrub the pots with a brush and rinse the outside of the pot with clean water.bull; Provided by Mary Boldan and Donna Siemro, University of Illinois Extension Master Gardeners. Send questions to Ask a Master Gardener, c/o Friendship Park Conservatory, 395 W. Algonquin Road, Des Plaines, IL 60016, (847) 298-3502 or via e-mail to cookcountymg@sbcglobal.net.