Myth: A layer of gravel at the bottom of plant pots aids drainage.
Fact: Water does not move easily from a layer of finer-textured material to a coarsely textured one. The coarser the underlying matter, the longer a pot takes to drain. So skip the gravel. (To prevent the potting mixture from spilling out of drainage holes—which are a must—as well as to let air in and keep bugs out, use a piece of window screening, mesh drywall joint tape or
a coffee filter in the bottom.)
Myth: Annuals and perennials won’t grow under evergreens because dropped needles make the soil acidic.
Fact: The acidity of soil depends mostly on the underlying bedrock. The real reason plants don’t thrive under evergreens is the soil’s extreme dryness and low fertility. That’s because the trees cast dense shade, take up most available moisture and nutrients, and shed rainwater to the edge of their canopies, keeping conditions dry below. For success beneath evergreens, choose shade- and drought-tolerant plants, water and fertilize regularly and mulch to preserve moisture.
Myth: Prune the tops of transplanted trees to compensate for root loss.
Fact: Pruning retards the establishment of transplanted trees. Leaves make food through photosynthesis, so taking away a good portion of foliage inhibits growth—and may also ruin a tree’s natural shape.
Myth: Crushed eggshells repel slugs.
Fact: Jeff Gillman, author of The Truth About Garden Remedies, found that a thick layer of eggshells slows slugs down a little, but it doesn’t repel or kill them. Insecticidal diatomaceous earth, however, works very well. This natural substance consists of fossilized skeletons of marine and freshwater organisms crushed into powdered glass-like pieces. When slugs get it on their bodies, they lose water rapidly through tiny cuts, then dry up and die. It also repels these pests because they try to avoid contact.