A drop to drink

As our area’s drought continues, wildlife has trouble finding water sources. My garden offers several.

 

Birdbaths offer water in dry times

     Back in 1997, we sank a rectangular plastic fish pond in the lawn and edged it with bluestone. A pump oxygenates the water and circulates it through a biological filter. 

The pond in May

For several years I brought home young koi from the garden center to live in the pond, but they all disappeared in a year or two. Some were clearly pulled out and eaten, possibly by raccoons. Half-eaten bodies were left behind. Other fish just weren’t there the next spring.

Koi weren't making it to this size

     I decided I’d assassinated enough koi and stopped restocking. Now the pond just houses water plants, and I’ve switched to hosting tadpoles. It’s fun to see them grow into tiny frogs that like to sit on the stones beside the water, jumping in as footsteps approach. 

 

Frogs are fun, and they eat insects

    Meanwhile, the pond provides drinking water for wildlife ranging from birds to squirrels to our dog Lola, who likes to wade in and pull out floating plants. Birds perch on the netting that covers the pond in winter to keep falling leaves from settling on the bottom. In this way they can walk across the pond to drink, safe from heavier predators.
 

    I’m pleased that toads have taken up residence in the garden, because they’re prodigious insect eaters. Toads are actually a kind of frog, and they too need to start their life cycle as eggs and tadpoles in water, so the toads I’m seeing may have been born in the garden pond.

 

A well-camouflaged toad

 
     Specifically for birds, I maintain other water sources as well. There’s a stone birdbath at the base of a redbud in view of the kitchen windows. The basin kept falling off its pedestal until I built a brick base for it, fearing that some small animal would be crushed. A ceramic birdbath spends the summer under a nearby crabapple. Birds approach cautiously, perching on nearby branches before landing in the water and puffing out their feathers for a wash. 

 

Birds like water near trees or shrubs

  Hanging from a spruce branch at the side of the house is a water bottle with a perch for birds. This one allows them to drink without the danger of landing near the ground.

 

A safe perch for cautious birds

     In the hottest weather, I’ve also put a few inches of water in a child’s wading pool to allow Lola to cool her feet. I notice that birds regard this as another larger birdbath. With all this standing water, I have to be careful not to provide breeding ground for mosquitoes. I empty out the water every two days, and each month I drop Bti (Bacillus thuringiensis subspecies israelensis) into the pond. It’s a safe soil bacterium that kills mosquito larvae.

    Friends, I’ve decided to stop posting on a weekly schedule. I find I’m running out of subjects. I’ll continue posting occasionally when a topic comes to mind. If there’s something you’d like me to write about, please let me know. Thank you for being with me over the years!

 

 

 

A fair exchange

An excellent summary by Anne Bikle in Fine Gardening reminded me that there’s no free lunch in the rhizosphere, the top few inches of soil where most of the biological activity happens. True, lots of soil organisms are at work breaking down organic matter into forms that our plants’ roots can use. 

Electron micrograph of soil microbes-photo Pacific Northwest National Lab

But that’s not a coincidence. The roots offer something in return. Every plant exudes proteins, carbohydrates and fats from its roots. These attract the organisms that help plants get what they need and protect them from diseases and pests.

 

Fungal network associated with spruce roots-photo André-Ph. D. Picard

 
    Bikle’s article was a good reminder to support this process by taking good care of soil organisms in the garden. I checked myself against her three recommendations: leaving soil undisturbed when possible, mulching to add organic material to the system, and growing a variety of plants.

    A few years ago I gave up turning the soil in the vegetable bed with my spade before planting in spring. I’d thought this was a necessary step to mix in amendments such as compost and composted manure and turn under any weeds that had sprouted.

     I stopped all this digging when I learned it was counterproductive. I was breaking up soil networks, killing or slowing down soil organisms that were nourishing my plants. I was also churning through organic material by introducing a rush of oxygen into the soil, wasting the compost I added to the bed. 

     I found out it was better to let soil organisms do their work undisturbed. Now I confine the digging to times when I need a planting hole for a seedling such as a young tomato plant. The soil in the vegetable bed has improved. As a side benefit, I’ve got fewer weeds, because when I cut out the digging, I stopped bringing weed seeds to the surface to germinate.

I avoid digging except to plant seedlings

    I’m also making a point of not clearing away leaves that fall on the ground, except on the lawn. I’m still working on striking a balance for fall leaves. I used to chop them up for leaf mulch, until I learned this also chopped up useful insects at various stages of development that were settling into the leaf litter for the winter. For the past couple of years, I’ve mostly let the leaves lie on beds, supplemented by more leaves I drag in from the street that would otherwise go to the city’s composting site. 

 

Letting fall leaves lie

     

     Now I’m missing my leaf shreds. There are places where they’d be especially useful, such as in the newest perennial beds, where the soil could use some quick help. The leaf shreds stay put, not blowing around like whole leaves, and they decompose faster. This fall I think I’ll do some limited shredding to cover those spots.

 
     From Bikle I learned that I’m offering a diverse buffet of root exudates by increasing variety in the garden as I’ve added native plants. That’s because each plant sends out its own recipe to attract organisms to meet its needs. All the better.

 

A mix of native plants: wild ginger, leucothoe, heuchera

 

Sharing

 At this time of year, the garden starts to look tired and ragged. This week I took the opportunity to reassure myself that chewed leaves aren’t a problem for garden plants. They have lots of ways to deal with chewing insects, and lots of leaves can be chewed without changing a plant’s beauty.

Canadian wild ginger

Humans aren’t that sharp about noticing chewed leaves. Research on aesthetic tolerance has found that 10 percent of the foliage in a garden can be damaged by herbivorous insects before the average gardener even notices.

Insects have been chewing the ginger leaves

     Plants notice, of course, and they’ve evolved a range of tools for turning away hungry animals. First there are mechanical barriers, such as the bark and thorns that some deploy. Without these obvious weapons, though, lots of other plants are ready with chemical defenses.

Closeup shows insect damage

 

Oxeye sunflower

     

 

 

 

 

 

 

     

 

 

We often hear about plants whose tissues are poisonous to leaf-eaters. Milkweeds (Asclepias spp.) can’t be eaten by any but monarch caterpillars because their sap contains toxic cardiac glycosides. Foxgloves (Digitalis spp.) poison browsing herbivores with digitalis in their tissues. 

    Other plants can generate chemical responses to browsing insects. Goldenrod, for example, sends out a chemical signal that keeps leaf beetle larvae from eating too much of each plant. A team at Cornell found that a chewed goldenrod plant sends out volatile organic compounds warning the larvae away from itself and its neighbors. The scientists found that the larvae preferred unchewed plants. 

Goldenrod can communicate with plants and insects

     The goldenrod’s chemical message also alerts nearby goldenrods to the danger so they’ll ready their own defenses. Each plant can lose up to 30 percent of its leaves and survive. In response to the chemical signal, the damage was spread out over stands of goldenrod. This seems like a win-win: the plants aren’t mortally wounded, and the insects get what they need.

    So as I walk around the garden noticing damaged leaves on just about every plant, I remind myself that there are enough leaves to go around. 

 

Leaf miner at work on a columbine

And I’m definitely one of those gardeners who doesn’t notice the chewed parts when I shift my attention to taking in the whole plant. Just as well.