My brother-in-law has many oak trees in his front yard and every fall he rakes up the leaves. I told him to just mulch them in (the soil is quite sandy) as they will help improve the soil. He said that would make the soil too acid. Will this dramatically raise the soil acidity? What if he composted all the leaves; would the compost be too acid to use as well?

Actually, your brother-in-law has a gold mine. Oak leaves in particular are very good for garden soil as they contain micronutrients drawn from the depths of the earth. The best way to add them into the garden is to rake them into a shredder or run over them with a power mower. The oak leaf needs to be broken up in order to release its nutrients. Then they can be tilled into the garden bed using a garden fork. If left intact, oak leaves mat together and promote unhealthy bacteria, which can be transmitted to planted material. Once shredded, they can be worked into the sandy soil, offering an excellent organic amendment to a soil that drains too quickly. It will not dramatically raise the soil acidity. The leaves can be composted but again, must be shredded or chopped up to effectively decompose. If mixed in with ongoing compost, they will degrade much faster and more thoroughly.

I planted a butterfly bush late last summer and it did very well. Early this summer new foliage appeared at the base but no new growth occurred on the branches. Am I supposed to cut the dead branches back to the ground or leave them alone?

One of the greatest treasures for providing life in the garden is the butterfly bush. Hummingbirds and beneficial insects, as well as butterflies, are seduced by the nectar-rich flowers of these bushes. Most plants offered are of the species Buddleia davidii. These large, hardy shrubs (even the dwarf shrubs can reach 8 to 15 feet) are highly ornamental, extremely carefree and very vigorous growers. Buddleias remain evergreen in winters where the temperature does not drop below 20 degrees. Where winters are more severe they can be deciduous, merely dropping leaves, or herbaceous, freezing completely back to ground level. Phenomenal growth is achieved in one season even if they do freeze all the way to the ground. The normal life cycle of this bush is to go dormant in zones 5 and 6. At this point the canes above ground are dead. In early spring, after any danger of hard frosts, they can then be pruned to the ground or you can shorten the main stems to a low framework of 6 to 18 inches. If you are in a marginal zone 5 area, it is a good idea to apply a 3- to 6-inch layer of mulch covering the crown. Since it self-seeds prolifically, it’s best to remove spent flower heads promptly. This results in a second flush of flowers in late summer. No landscape should be without at least one butterfly bush!

I am trying to hide my air conditioner unit. What plants can I place around the unit that will not harm it, nor the unit harm the plants?

That all depends on the air conditioner’s location. If there were a large planting area, you would be better served to distract the eye from the unit with a mixed planting of woody ornamentals and tall grasses, as opposed to drawing attention to it with the ubiquitous soldier course of evergreen shrubs. Always allow a constant 3- to 4-foot minimum clearance around the unit for the inevitable maintenance and for proper airflow. Now, if extra space is at a minimum, such as your condenser being adjacent to the patio, it would be better to have a screen, such as vented fence sections surrounding the visible sides. Dry-set the posts so the sections can be removed for servicing. If done well, it would add an attractive privacy screen effect as opposed to a cover-up.