Habitat Tips

Rethinking Leaves and Garden Clean-Up

One of the most valuable actions we can take to create habitat for pollinators and other insects is to provide year-round cover and nesting sites. Leaving fallen leaves and dead plant material during the fall, winter, spring and summer is the best way to ensure that insects have the essential shelter to complete their life-cycles. These insects, in turn, are a crucial food source for birds, and the dead plant material also provides birds nesting material and screening for safe foraging.

Removing fallen leaves and cutting perennials to the ground are well-ingrained garden practices. However, it’s within this debris that bees, caterpillars, beetles, spiders, and other insects make their home, find protection from the elements, or lay their eggs. As the Xerces Society explains in this article, “the vast majority of butterflies and moths overwinter in the landscape as an egg, caterpillar, chrysalis, or adult.” If we discard this debris, we also discard the following season’s insect diversity before they complete their life cycles!

a garden with neat edges Grow Wild’s garden clean-up tips:

  • Focus on neat edges. It's important to show that a yard is being taken care of. Tidying a 6-12” strip along the front of garden beds and walkways, while leaving leaves and plant debris in the interior, demonstrates intention while still maintaining insect habitat.
     
  • Keep leaf accumulation natural. Avoid blowing or piling extra leaves onto garden beds or into forest edges. More than 6” of leaf cover can smother even native woodland plants.
     
  • base of tree with designated area for soft landings Designate areas for Soft Landings. Leaving natural, unshredded leaf litter directly under trees and shrubs allows insects to complete their life cycles. Plan areas under trees where the leaves can be left in place then add some pollinator plants.  Additionally, the nutrients of this leaf litter are recycled back to the tree.
     
  • Manage excess leaves. It’s understandable that not every leaf can be left where it falls. Designate an inconspicuous area where leaves and plant material collected from sidewalks, storm drains or lawns can be piled whole to decompose over time. If you don’t have a need for compost, take the leaves to a municipal compost facility. Leaves that fall on the lawn can be mowed to recycle their nutrients for the lawn and nearby tree roots.

    diagram of keystone plants
  • bee in dead wood Maintain some dead wood and brush piles. A diverse number of insects utilize decomposing stumps, logs, and branches as food or nesting sites. The tunnels they create may be used as nesting sites for solitary bees. Moreover, many birds forage on the protein-rich insects living within decomposing wood, and find much-needed shelter within the branches of a brush pile. Here are additional brush pile tips from the NurtureNativeNature blog.
     
  • Leave flower stalks standing. Stem-nesting bees utilize the pithy or hollow stems of perennial flowering plants and grasses in which to lay their eggs. Different species emerge in different months over the course of the season. Cutting dead stalks to 8-24” tall, rather than to the ground, provides the female bees nesting opportunities. Drop the cut pieces at the base of the plant for a natural mulch, which may also be used for nesting. New green shoots will quickly grow to hide dead stems. The University of Minnesota Bee Lab handout is an excellent summary. This North Carolina State Extension article lists favored plant species.

    bee larvae
  • Resist the spring clean. Although Champlain Valley humans seem to ignite into action with the first warm day of spring, insects are different. Each of the vast number of insect species are cued to hatch from eggs or emerge from pupae as adults based on a unique “combination of day length and accumulated degree days”, which happens in different months, spring through fall, as explained by entomologist Doug Tallamy. Leaving plant material all year long ensures that insects have essential shelter to complete their life-cycles. 

Cutting Back Stems

cross section of a mason bee nest in old wood. Some of our native bees nest in last year’s dead flower stems or woody cavities. Heather Holm, biologist, award-winning author and pollinator conservationist in Minnesota, helped create the linked graphic below and shared these photos to explain how they use the dead stalks.  

Our native stem-nesting bees will lay their eggs in dead stalks and provision the egg cells in year one. The eggs hatch into larvae which mature into adults over the next 11 months if they’re not disturbed. 

IF we need to cut back garden stems, we look for the 

  • pithy or hollow dead stalks that have 
  • ⅛ inch or greater centers and 
  • cut them to 8-24” tall, 

breaking the rest into pieces to leave around the plants as mulch and recycle their nutrients naturally. New green shoots will quickly grow to hide the dead stems.

That’s a small carpenter bee working on its nest in a pithy stem and a cross section of a mason bee nest in old wood. 
 

Learn more: How to create habitat for stem-nesting bees

small carpenter bee working on its nest in a pithy stem

Track and ID Insect Visitors

Native plants attract diverse insect visitors: native bees, flower flies, beetles, solitary wasps, butterflies, caterpillars and more. Not all will be prominently feeding from flowers. Many are inconspicuous, either camouflaged or leaving behind evidence such as cut leaves or minute droppings. The presence of insects is an indication of a healthy natural community. It is rewarding to identify these beneficial guests! 

We recommend setting up an iNaturalist account to not only help ID what you’ve found but to contribute to community science, e.g. Vermont Center for Ecostudies’ Vermont Atlas of Life . Community scientists contribute over 95% of Vermont’s biodiversity records and Vermonters contribute more field observations per capita than any other state!

screenshot of inaturalist iNaturalist offers a great guide for getting started on the app or scroll down on this site for some how-to videos. Here are a few additional tips based on our experience: 

  • Getting the right photo to use on iNaturalist takes patience. Move slowly and maintain sharp focus. Select the shot that shows key features, crop it and post to your iNaturalist account.  The app's algorithms will suggest some IDs. 

  • Review the suggestions and select the best match.  Note whether the suggested insect is active at the time of year the photo was taken. For example, if your photo was taken in May and the insect is only active in August, it’s not a match! Likewise, if the species has not been seen in this part of the country, it’s likely not a match either. 

  • Experts will confirm or suggest another ID. Once two agree on the species ID, it is designated Research Grade. Scientists have also created “Projects” to join. For example, users can help track  which plant species are favored by leaf cutter bees! 

We’ve learned a lot by observing, photographing and uploading our photos, and scientists are grateful for the observation data. You may observe a bee, beetle or moth rare to science!

When to Water

annotated photo of watering tools (can, hose, nozzle, sprinkler, rain gauge) Although established native plants rarely need watering, ensuring they get consistent water their first year is important to develop deep drought tolerant root systems. Newly planted trees need our help for the first 2-3 years!

  • Use a rain gauge or a level straight-sided container to measure rainfall. If it records 1 inch a week, no watering is needed.

  • When installing your new plants, shape a level bowl around their stem for watering their root zone. Be sure this area is well soaked to a 4-6 inch depth. New large leafy plants may require more water since those leaves will be transpiring water back into the air. 

    • diagram of bow size for root zone 2-4 feet plus for shrubs and trees which will need 5-20 gallons of water, depending on their size, to encourage deep rooting. Tree gator zip-up watering bags can be helpful.

    • 12-16 inch diameter for gallon and larger pots.

    • 6-8 inch diameter bowls for plugs or small pots.

  • Observe how your plants respond so you can figure out their needs.

  • It's better to water late in the day so the water soaks into the soil in the cool of the evening vs. evaporating quickly in the midday sun.

Mulch and Compost

New plantings that replace regularly mowed and leaf-raked lawns typically require adding a layer of compost and *arborist wood chips to jump start beneficial fungal/soil biota activity and add organic matter and nutrients. Chips from hardwoods are preferred to pines, etc.

leaf litter Woodland edge and moist meadow natural communities typically have high organic matter from leaf litter or dense meadow vegetation respectively. When rewilding shaded or soggy lawn sites, layer 2-3 inches of compost followed by 1-2 inches of wood chips to mimic these conditions. In future years, leave the fallen leaves, stems, branches, and deadwood in place. 

Sandy sites and thinly soiled outcrops are naturally lower in organic matter and nutrients. When re-wilding these areas, layer 1 inch of compost followed by 1-2 inches of hardwood chips. These drier plant communities won’t thrive with excessive nutrients but need a starter boost in their first year. 

This Mulch Guide from Brooklyn Bridge Park is an excellent summation of the pros, cons and subtleties of using mulch, including sheet mulching.

*Here’s more in-depth information on the benefits and types of hardwood chips: Ramial Chips - Maine Organic Farmers and Gardeners.