Living with Low Water Plants, Part 3: Soil Building in the Garden

Soil health is essential for any successful garden or landscape.  As we touched on in previous installments in this series, the microorganisms in the soil are in effect the unseen stewards or caretakers of the soil. Without these tiny soil workers, the available nutrients never make it to plant roots and hence, soil & plant health can decline.

The leading reason for deteriorating organic life is the absence of organic material in the soil. Years of over feeding soil with harsh chemical fertilizers, such as are common in conventional turf-lawn maintenance, will eventually over saturate and effectively render the soil lifeless. Lifeless soil produces poor results with any plant, despite claims that California native plants prefer, shall we say "poor" soil. In fact all plants like well draining soil with some available nutrients.

Another factor to consider when dealing with soil preparation for areas intended for new plantings; most nursery propagated plants are grown in perfectly textured, well draining soil with a slight preference for the sandy-loamy.

Sustainability on the Ground: A Question of Accessible Values

In addition to living organically or "veganically" (meaning no animal byproducts; manure, bone meal) , some people are also seeking ways in which to minimize their overall wastage or carbon footprint in general. In this article we will be focusing on soil building (not surprising) which as it turns out, is one of the single most important "at home, in the available landscape you already have" practices which, along with regular weeding, rounds out the foundational or core aspects of any functioning organic garden and solves for many kinds of unseen resource wastage.

Creating Soil: Composting, Green-Cropping & Soil Building

Compost needs full sunlight, periodic watering and turning for aeration to decompose completely and correctly without creating mold. Some prefer, due to the unsightly aesthetic appeal of large mounds of what look to be scraps (they are!), to simply dig a series of pits in which to stage each respective pile. While this is certainly a handy way to control the organic compost you will be making, it also adds additional labor to the already constant task as well as giving rise to the potential for fungal residue due to water which can collect & remain in the pits, so we prefer to simply leave the compost mounds above ground and in the open light.

Green Crops: The Life of the Party

To add a source of needed nitrogen, we like to set aside some portion of the garden to grow what are called "green" or nitrogen-rich cover crops. These are very simple to grow and are sown by seed and raked in just below the soil surface. The seeds are left alone during the winter months to establish by the rains.  Some common plants used in green crop seed mixes are:  wheat, vetch, rye, and fava beans.

Growing green cover crops has a variety of benefits in the organic garden including the ready provision of nitrogen-rich plant material but more, the plants themselves fix nutrients at the root level, which means that even after cropping the topical plant materials, the soil is left fresh and ready for turning or replanting as the bed is now rich with fixed nitrogen the plants can readily use.

Looking at the above photo on the left, we see that the green crops are purchasing the soil to a fairly good root depth, which means that the plants are, through the rooting actions, breaking up and aerating the soil. As we magnify and rotate a detail shot of the actual root base we can clearly see the fixed nitrogen nodules now collected just below the soil surface at the root level of the plants. When mature, the topical green-crop plant material gets cut down to the surface and added back to the lifeless clay or old soil, while the now nitrogen rich roots and soil in the original green crop bed can be turned and replanted or cashed as additional amendment.

Starting the Organic Engine: Make Haste Slowly

To begin this cycle you will first need an adequate amount of compost to make the "exchange" - so begin saving all your cuttings! We start this cycle by removing the top six inches of any given planting bed if said bed is heavy clay or simply lifeless (meaning no micro-organic activity) and with this, make a small pile. Add to this pile of clay or old soil the plant-clippings and existing organic green-crop compost at a 50:25/25% ratio, meaning 50% old material, 50% new material, if possible. This pile of 50% old material and 50% new organic material will need to rest for anywhere between three weeks to two months depending on the climate and materials added to the piles. When this has been mixed and turned several times, it is moved aside to age or decompose completely. This becomes our on-site, nitrogen rich all organic compost.

The mounds are separated and spaced apart 

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Brown or "Cold" Material Pile: Back in Black

This pile is actually the first to be made and separated from the rest, as it consists of all the materials to be sorted out which are unsuitable for use in an organic compost pile for a variety of reasons. 

The density of wood helps it resist rapid decomposition, which is so necessary for good organic compost. Also, brown or hard material as it decomposes adds, by percentage, more carbon than nitrogen, which is why it is often labeled "cold".

Some of the materials we avoid adding to our compost piles are hardwoods or any cutting in excess of 3/4 inch as these generally take too long to decompose and really only add carbon or 'cold' value.

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Green or "Hot" Material Pile: What Thrived Once, Lives Again

 Green materials consist of almost any plant or leaf material from almost any source. In most gardens, due to regular plant cycling & mortality, there is typically ample available material with which to start a green or "hot" materials cutting pile. Again, it is important to sift the green cutting well for rogue branches and overly-stout stems. Avoid adding any processed (human) foods as sugars tend to attract flies and animals. Stick to bright green vegetable and plant material in general and your compost should be pest free.

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 Existing Soil or Clay Pile: We've Only Just Begun

This is a pile of soil or clay which was extracted from existing beds, older plantings and through soil cycling. Soil cycling is a method of exchanging poor soil with nutrient rich amended soil which is made on site, then returning the upgraded soil back to an existing bed. If cycled judiciously, most gardens can be completely rebuilt in a couple seasons without any store bought fertilizers.

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Mixed Pile of Clay & Hot or Green Clippings: Speaking Words of Wisdom, Let It Be
This is the amended soil, now 50% old matter and 50% new to which we added the fully grown and harvested green crops. This pile will need to be watered and turned frequently for 2-3 weeks, depending on climate and composition.

Rebuilding the soil balances the garden or landscape ecosystem from within its own boundaries. Starting with extremely clay-heavy soil, we have been able to produce friable, well draining soil full of life and nutrients.

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Finished Organic Compost: Gardeners Black Gold

Once the material has broken back down into essential components it will resemble normal soil, will look rich & black (almost like spent coffee grounds) and should already be showing signs of attracting beneficial insect & other life. Return this soil directly back into a previously cached bed or use liberally as a top dressing for existing beds & plantings. 

Creating a self-sustaining system of returns is a huge undertaking for any gardener. The very idea of creating a "sustainable" garden implies quite a bit of planning followed by the certain promise of labor. With foresight and some good 'ole elbow-grease, virtually any garden can be transformed from within its own borders. Old soil can be brought to life, balance can be established organically, if we only identify and engage with the existing natural machines which are already functioning around us.

Questions

Some general considerations when it comes time to restock on soil for the garden or landscape:

1) How much energy does it take to get the soil to my location?

Have you ever stopped to wonder how many gallons of fuel and how many man-hours of labor it takes to produce one bag of store bought "organic" compost? The reality and associated costs may be surprising. By creating the needed nitrogen sources and by rebuilding soil on-site, we can effectively liberate our gardens and landscapes from the petroleum and energy intensive chain of driving to purchase soil which had to be delivered to the supplier in a large truck in the first place.

2) Where do all my leaves go?

Another interesting factor to consider is the use of our collective space. There is a great deal of transportation and storage at the civic level dedicated to organizing and off-loading the endless masses of leaves, twigs, grass clipping and other cast-off plant materials emanating from the urban landscape. If we can reuse and revitalize a significant portion of our plants, we can avoid participation in endless energy burning cycles, which helps to ease the strain on public landfills.

3) Where is the organic compost from? 

In many cases large rockeries and landscape material suppliers are reselling "organic amendment" which is sourced at the local landfill, which includes the local grass clippings and all the various chemicals used in routine lawn maintenance. Unless you are creating your own soil, either you are extremely well informed or you are not really that concerned at the contents of the soil. Often, we have found that two different suppliers were reselling city compost which was simply retreated.

Saving energy, increasing efficiency while ensuring health for the garden and yourself, is a great way to engage in home grown sustainability. It's a great workout, too.

See more in our Living with Low Water Plants series:

Part 1: Plant Installation
Part 2: Using Drip Irrigation

Part 3: Soil Building in the Garden

Part 4: Plant Maintenance

Part 5: Holistic Economics

Living with Low Water Plants, Part 2: Using Drip Irrigation

Today's resource-conscious consumer is always eager to find new & improved ways to save the environment while saving a buck. As it turns out, using drip irrigation can be one of the main at-home or do it yourself steps which simultaneously addresses the broader issues surrounding water management and water conservation. Used in conjunction with adequate mulch and a properly functioning system, drip irrigation becomes the circulatory system in the garden, the veins of the organism of your garden. In this short article we will be discussing some of the common techniques we use to minimize costs and maximize results using soft-line, drip irrigation to provide water delivery to low water plants in the San Jose, San Fransisco Bay area climate.

Many of our customers are in the process of revitalizing some aspect of their landscape, weather it be a small bed, the front garden or the entire landscape, one thing is certain; the need for correct installation and adjustment of drip irrigation can make the difference between a successful garden and the potential alternative. Thankfully, many of the low water and California Native Plant selections are famously tough, so even when running dry or suffering from other adverse conditions, the plants tend to hold up rather well.

Waste Not, Want Not: Dollar By Dollar, Drop By Drop

Drip irrigation also has the advantage of being low pressure, meaning that in ideal conditions one can get away with watering quite a few plants with only one valve. Also, being that most drip heads are flow adjustable, meaning they can be fully adjusted or closed completely with no need to change anything at the valve. In conventional landscaping (you'll note the use of "conventional" in association with turf-lawn) one would need a separate valve for every area. With drip, this becomes a non-issue as water can be adjusted for each and every plant or closed completely.

In terms of water application the difference between conventional turf-lawn spray and drip irrigation is notable: Spray is measured in gallons per minute, whereas drip is measured in gallons per hour. That means that conventional pop-up or radial spray heads can use up to five times more water over the same time period; notable indeed. Add to this the fact that conventional turf-lawn not only takes more water at the root level to keep happy, but also loses more water out of its own surface area as the water heats up and vaporizes. It's not hard to see how the potential savings of using low water plants extends far past the up-front savings in water delivery.

Transpiration & Evaporation: The Real Issues

There are a few simple values common to all plants, which we need to take into account when diagnosing the water delivery needs in the landscape: Temperature, humidity, wind, soil moisture and type of plant. We call the group of these values local to your garden the "micro-climate".

According to the USGS:

"10 percent of the moisture found in the atmosphere is released by plants through transpiration."

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. Transpiration also includes a process called guttation, which is the loss of water in liquid form from the uninjured leaf or stem of the plant, principally through water stomata.

Evaporation is the process by which the surface of water is heated and slowly turned into vapor. Evaporation accounts for 90% of the water returning into our atmosphere mainly from the surface of the oceans, lakes and other bodies of water.

HOW TO

Use 1/2 inch softline, then run to each plant with 1/4-inch tubing.

Bury softline in mulch, not in the grade. Run the 1/2'' line around small mounds.

Remember: Keep all emitters above grade. Burying emitters in soil can lead to the emitters being eventually clogged.

Ideal drip zone in between the crown & edge of canopy; feeder roots actually move away from the crown (center) of the plant, which means that water delivery should take into account not just the area within the canopy, but also slightly outside the canopy.

Drip irrigation is ideal because of adjust-ability to each plant, ease of installation and low up front costs.

Most people think drip is used primarily in vegetable garden applications, but in fact we use drip exclusively unless there is a large grass area or if there is specific need to field-broadcast water. This is a notable issue for anyone interested or concerned with water management. As we touched on in the previous installment, adding mulch periodically keeps roots covered and builds soil. It also serves to insulate the plants roots and the microorganisms which thrive in the soil.

The drip heads that we prefer to use come in two varieties, 360* spider-stream and 360* spray. Since most drip heads are adjustable in gallons-per-hour (rather than gallons per minute as with conventional pop-up spray heads for turf) we tend to use the ones with the broadest flow rage, which usually ends up being 20 gallons per hour.

The spider-stream drip we use where we want an even distribution in a small area, usually delivered to the roots of a single plant. The 360* micro-sprays are good for wider areas or larger clumps of ground cover which necessitates overhead spray.

For a more technically complete review of drip irrigation systems visit: The Urban Farmer Store

See more in our Living with Low Water Plants series:

Part 1: Plant Installation
Part 2: Using Drip Irrigation

Part 3: Soil Building in the Garden

Part 4: Plant Maintenance

Part 5: Holistic Economics

All content (c)2010 Patrick & Topaze McCaffery

Choisya Ternata

Now Flowering - March 2010:  Choisya ternata (Mexican Mock Orange)
Location:  San Francisco Bay Area Region

Foothill College's Environmental Horticulture Department holds Spring and Fall plant sales every year to raise money for the Environmental Horticulture & Landscape Design program. I adopted our Choisya ternata from Foothill College in 2006, during their Spring sale. I purchased it because it was alone in a corner with only 2 twigs sticking out of clay soil, with a few leaves on the ends, apparently saved from a garden demolition. For $3.00 I brought it home. It started out in a 5 gallon pot and four years later, it's still in the same pot, only I replaced the clay soil with rich, well draining soil. I keep it close to the perimeter of a Redwood tree and allow the Redwood leaf fall to cover its base during the Winter. With yearly pruning after blooming, it continues to grow delightfully in a pot. The white flowers almost 'glow' above the dark green leaves, as these photos show, taken at twilight on March 9, 2010.

This evergreen shrub has clusters of lightly fragrant white flowers that bloom from early spring to early fall and are highly attractive to bees. Placing Choisya ternata plants in the garden where they will get full sun early to mid-day and partial shade during the hottest hours of the day keeps their leaves from scorching.

I feed ours with fish emulsion in late February to early March and by May, after flowering, prune it by 30-50 % to keep it tidy so that it doesn't get top heavy and topple over in its pot.

Topaze

Living with Low Water Plants, Part 1: Plant Installation

With ecological consciousness forever on the rise, people have become more & more interested in the potential of low water, low maintenance plant selections to serve active duty in the urban landscape. Typically, at the end of winter, the inner-gardeners come out of the cask and make their seasonal inquiries about the possibility (and price) of having a beautiful new low water garden installed in their landscape. Of course, we are only too happy to provide vision, experience and direction to this wonderful process.

However, there are many important differences between low water plants and other more commonly used plants and we need to take these differences into account from the very start to ensure proper establishment. Most low water plants, and certainly most California native plants, tend to be much tougher and more resilient to our local weather extremes - this is of course only if the plant is being installed and watered correctly. Low water and California native plants typically need very little amendment or fertilizer and can tolerate minimal water and poor soil conditions but they also tend to be particularly sensitive to over-watering and over-moist soil conditions. Seeing that we work almost exclusively with low water and California native plants in the San Jose and San Fransisco Bay Area.  We thought it may be helpful to cover a few of the essential techniques we use to ensure healthy, vibrant plant establishment when using low water plants in the urban landscape.

Establishment & Mortality: What Begins Well, Grows Well

Plant mortality is a common problem among young plants and newly installed gardens, especially in gardens which are installed during the heat of summer. This potential loss of plants is mainly due to shifts in the plants surrounding environment. Drastic changes in temperature, water transpiration and light exposure certainly play huge factors - but these tend to be endemic or unalterable aspects of ones micro-climate situation. Past growing your gardens indoors in heated greenhouses, no matter where the plant is in the landscape, regulated water application, soil health, drainage, suppressing weed growth and regular pruning are the main ways we can affect and protect plant health.

Of course every plant must be placed in the correct conditions to survive long-term based on its own unique needs. We, as gardeners or garden-stewards, can help without using any harsh chemicals or chemical fertilizers. Think about it - for thousands of years farmers simply did not have chemical herbicides or pesticides, relying solely on naturally occurring nutrient and mineral sources and sweat equity. While natural sources can't compete with the highly concentrated chemical elements, it does indicate that these same elements and nutrients are in nature everywhere found in abundance. We only need adequate motivation and foresight to put these elements to use.

Through the simple application of high plantings and copious mulch - with a bit of organic compost every so often, we can successfully solve or avoid many of the common issues which affect young, struggling low water and California native plants while creating ideal soil conditions and maintaining a healthy environment for you. In this small article we will be discussing the process and benefits of planting low water plants correctly, using mini-mulch to insulate and feed the root-level soil, building organic compost (soil building) and drip irrigation for adjustable water delivery.

Soil Texture & Quality: A-O-M

Soil quality is as variable as the weather. Here in California, specifically in the San Jose and San Francisco Bay Area we have a great deal of clay-heavy soil. To solve this, as our instructors at Foothill's wonderful Environmental Horticulture and Design program used to say, first we must recite the mystical soil mantra, AOM: Add Organic Material. By adding organic material (leaf clippings, plant material, compost) you can gradually re-supply the soil with the needed nutrients to attract the beneficial little insects which live and thrive in the soil.

The insects and other life forms in the soil, of which there are tens of thousands per square meter, aerate the soil and fix nutrients into forms the plants roots can use. The pests we find in the soil, one group of which are called Springtails (Collembola) are actually a "main biological agent(s) responsible for the control and the dissemination of soil microorganisms", even though we tend to think of most bugs or insects as pests. When the individual numbers of these living organisms are depleted, soil health can decline, leading the soil to become anaerobic (lacking air) which can attract weeds and other undesirables. A contemporary method of soil analysis focuses not only on the appearance of a specific elements & minerals in the soil, but in counting the number of insects and other living organisms in the soil to more accurately judge the soils viability.

Root-Soil Contact in the Planting Hole: Using Mycorrhizae Mycorrhizae is essentially an intelligent networking fungus (oh, don't be a sore spore!) which attaches itself to the roots of the plant and actually elongates the roots, which increases the plants root surface area which increases nutrient flow & availability. This fungus attaches itself to other functioning subsurface fungal networks and then mediates the passage of nutrients, air & water to all plants connected in the network. In this way, Mycorrhizae acts as a subsurface root enhancer and it's already found in nature.

In our experience, the usage of Mycorrhizae in new plantings has almost eliminated plant mortality and seems to super-charge the health and flower production of the plant itself, and it's all organic and non-toxic. Interestingly, this smart-fungi also seems to actually prey on unsuspecting organisms such as the aforementioned Springtails, "one of the most abundant of all macroscopic animals" with which the fungus procures a ready source of nitrogen.

To purchase Mycorrhizae as a powder form, one only has to search online for organic sources or even talk to someone at your local (gulp) Commercial Turf Supplier as Mycorrhizae is used on almost all turf & lawn applications at the professional level. It's surprising to see how few people actually use this fundamentally important fungus in low-water landscape installations.
*Please Note - Mycorrhizae is not suitable for some plants. Please be sure to inquire before application.

Plants on a 3-4 inch high mini-mound: Don't Drown the Crown
Planting low water plants just a bit higher out of the soil serves two main purposes; it keeps the root-crown clean and dry, thereby avoiding rot and secondly, allows for deeper mulch application around the plant - the key to weed suppression. With 3-4 inches of mulch, weeds have a tougher time spreading roots and are easily hand pulled or turned with a flat-head shovel right on the surface of the mulch.

As a general rule, any plant can become unhappy in poorly draining soil. Plants which are sitting too low in the soil can also become covered, sometimes over the root crown, by standing water. This can make low water or California native plants very sad. Plainly, most low water plants and trees should not be visibly sinking into the ground. Also, surrounding the plant or tree with rocks does nothing at all, except to needlessly compress the roots & root-crown. Avoid it or undo it if you can. A hard and fast rule is to leave the base & crown around any plant or tree as clear as possible, with the exception of appropriately spaced companion plantings and mulch. It's crucial for plant and tree health that air transpires evenly through the root & crown at the soil level. Stacking rocks in a tight circle around the base of any plant or tree is like affixing a small noose which only serves to stifle air & water passage.

Most low water plants and trees need to be planted notably above grade to allow for adequate mulch depth and to account for future sinkage, in that many plants & trees gain considerable mass and will often sink into the planting hole over the first 3-5 years. To avoid sinkage make sure that the planting mound is firmly packed and that you start with reasonably dry soil before planting. Many large plants sink due to overly wet soil during installation. As the soil dries, the excess water and air eventually evaporate through the surface or transpire through the plant, which creates tiny pockets of space around the root area of the plant, which leaves the plant low in the soil. This is not to suggest that the plant should not be well watered in, it should, but we should start with dry, firm soil.

Use 3-4 inches of mini-mulch or micro-mulch: Mulch is the Key
We use primarily micro-mulch or mini-mulch for a few simple but tested reasons. First, mini-mulch decomposes faster than larger gauge mulch chips, which means that you won't find the same tired mulch chips 20 years later in your front planting bed. During this natural decomposition process, micro-mulch actually becomes or creates new soil. Many kinds of mulch will be slightly acidic which is perfect for many types of low water plants & trees. Plus, we think it looks nicer, too.

Another great benefit of deep mulching is that it provides a degree of frost & heat insulation for plant roots and the micro-organisms which live in the soil. It's important to protect roots and soil organisms from frost in the winter and excess evaporation in the summer. Because mulch can help the soil retain water, it plays a vital link in the reduction of water usage. Coupled with low water & California native plants, we have worked in many situations where, with correct planting height, good draining soil and adequate mulch, many plants need little additional watering after the initial 6-12 months of establishment.

Using the correct drip irrigation system means that you can have very low cost, adjustable water flow delivery to each & every plant, even when all plants are on the same valve. Please visit us again to read more in our next installment Living with Low Water Plants, Part 2: Using Drip Irrigation.

See more in our Living with Low Water Plants series:

Part 1: Plant Installation
Part 2: Using Drip Irrigation

Part 3: Soil Building in the Garden

Part 4: Plant Maintenance

Part 5: Holistic Economics

All content (c)2010 Patrick & Topaze McCaffery