Avoid These 5 Common Mistakes That Attract Garden Pests

Are you accidentally inviting garden pests and diseases?

Nothing makes a gardener’s stomach drop quite like walking out to water one morning, only to find the leaves on the plants you worked so hard to grow are wilting and yellow — or worse. While it certainly feels like garden infestations pop up overnight, more often than not, they build slowly as well-intentioned gardening habits create an environment tailor-made for unwelcome pests and pathogens.

Without realizing it, even seasoned gardeners can create the perfect storm of shelter, excess moisture, stressed plants and predictable food sources that draw pests in like a moth (larvae) to a — well, you get it.

The good news? Small changes in how you care for your plants can keep your garden from becoming a bug-and-bacteria buffet. Here are five common mistakes to avoid, along with easy fixes. 

Common Mistakes That Attract Garden Pests

1. Using too much — or too little — mulch in the garden

Mulch is the underappreciated workhorse of the garden. When applied correctly, it conserves moisture, moderates soil temperature, suppresses weeds and helps reduce the spread of disease.

Avoid these common mulching mistakes

However, misapplying mulch can create a host of problems. For example, excess mulch can trap moisture and create ideal habitats for slugs, fungi and rot — especially when piled against stems or trunks. “Mulch volcanoes” are a common culprit, as are heavy mulch layers around moisture-loving plants like hostas (Hosta spp. and hybrids).

Too little mulch can also stress plants by creating uneven moisture levels in the soil and allowing weeds to compete for water and nutrients.

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2. Watering plants at night

Evening watering often means foliage and turf stay wet overnight, creating ideal conditions for fungal diseases and some insects. Lawns are especially susceptible — diseases such as brown patch and dollar spot thrive with too much moisture.

Ornamentals aren’t immune, either. Prolonged leaf wetness can lead to powdery mildew, leaf spot diseases, root rot and increased pest activity on popular picks such as garden phlox (Phlox paniculata), bee balm (Monarda spp. and hybrids) and zinnia. (And if that wasn’t enough to deter you, nighttime watering can also increase mosquito activity.)

Watering earlier in the day, ideally in the morning, allows plants to absorb moisture while giving foliage time to dry before nightfall.

3. Replanting in the same spot after an infestation

Many pests and diseases are specific to certain types of plants and can hide in the soil between growing seasons. Replanting the same plants in the same location allows problems to recur and even intensify.

Avoid planting tomatoes or peppers where you previously had disease issues, and keep cucumbers, squash and melons away from the site of a squash bug infestation. And if you dig out your garden phlox because of a powdery mildew infestation, don’t plant more in the same spot. Same goes for black spot on roses (Rosa spp. and hybrids) or rust on hollyhocks (Alcea rosea).

Rotate vegetable crops to avoid recurring issues

Rotating crops disrupts pest life cycles by removing their preferred hosts. Even simple swaps — moving plants to a different bed or section each year — can significantly reduce recurring issues. See a simple crop rotation example in the illustration above.

4. Planting too early in spring

Many insects emerge and feed during early planting periods. While it’s hard to resist the temptation to get a jump on the growing season, plants put in the ground too soon may be exposed to peak pest activity before they’re strong enough to withstand the damage.

For example, bean leaf beetles often target early-planted green beans, while beans planted a few weeks later may escape the worst damage. Cucurbits planted at the first hint of warm weather can also be more vulnerable to squash bugs and cucumber beetles.

Early planting can negatively affect flowers, too. Tender annuals such as petunias (Petunia hybrids) or impatiens (Impatiens hybrids) planted when nighttime temperatures are still regularly in the 40s and 50s (F) may grow slowly, producing soft new growth that attracts aphids. Aphid populations can build quickly in the spring, before beneficial insects are abundant enough to control them.

Consider timing when harvesting crops

Harvest timing matters as well. Cool-season crops like lettuce, spinach and peas that linger too long in warm weather can attract late-season pests and disease, so be sure to enjoy your produce at peak freshness.

Adjust timing to help dodge garden pests

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5. Leaving diseased plant debris in the garden over winter

Many perennials, ornamental grasses and shrubs can provide critical shelter and food to animals throughout the colder months. However, sometimes leaving behind dead leaves and spent annuals provides insulation that allows insects, eggs, larvae and diseases to survive the winter. When spring arrives, those pests and pathogens are already in place to infest new growth.

For example, in vegetable gardens, squash vines left in beds can harbor squash vine borer eggs, while tomato debris may bring blight spores from one growing season to the next. Flower gardens face similar risks. Peony (Paeonia hybrids) foliage can contain botrytis blight (gray mold), and diseased rose leaves can carry black spot through winter.

Break the cycle by removing infected material

Removing spent plant material that is diseased or infested before the snow flies helps break pest and disease cycles. While you can compost or leave most healthy debris in place, you should discard anything that looks suspicious.

Plants that tend to harbor pests and disease overwinter

This list of edible and ornamental plants is especially prone to harboring pests and diseases if left standing over winter. Consider removing them if they show any signs of pests or disease during the season to avoid carrying those problems into your garden the following year.

Edible Plants

• Bean
• Cucumber
• Eggplant
• Melon
• Squash
• Pepper
• Potato
• Tomato

Ornamentals

• Bee balm
• Hosta
• Peony
• Garden phlox
• Rose
• Zinnia