IJ Archive

Saffron is one of the most expensive spices in the world—but did you know you can grow it right in your own backyard? With a little effort and patience, Marin home gardeners can cultivate Crocus sativus, the plant that produces saffron, even in containers or raised beds. This fall-blooming flower grows well in Marin’s Mediterranean climate, making it a great choice for those looking to add something special to their home garden.

Saffron comes from the bright red stigmas (threads) of the Crocus sativus flower. To grow your own, you'll need to buy corms online or at specialty garden stores during late summer.

When buying, larger is better. Big corms, corms that are 3.5" (9cm) or greater in circumference, can produce two to four flowers.  More flowers mean more saffron. 

Saffron can be grown in containers, raised beds, or directly in the ground.

• Containers are great for patios and small spaces. Choose a pot that’s at least 12" deep.
• Raised beds offer excellent drainage and make it easier to manage weeds. Hardware cloth or weed cloth at the base of the bed deters pest damage.
• In-ground planting works well if your soil drains properly, but beware of pests.

An especially creative method that works well in Marin is using milk crates lined with weed cloth. This setup gives your corms plenty of drainage while keeping the soil contained and weed-free and keeps pests out. Just fill the crate with a well-draining soil mix.

If planting in the ground, watch out for gophers, voles, and other burrowing pests, which may dig up or damage your corms. Wire mesh or underground baskets can help protect your crop. Deer also enjoy eating the flower and leaves of Crocus sativus.

Plant saffron corms about six inches deep and four inches apart in late August or September, before the rainy season begins. This gives them time to settle in and send up leaves before flowering in late October or November. Avoid overcrowding, as that reduces production.  

Saffron corms will sprout leaves soon after planting. Flowers usually appear in mid to late fall, around 6–8 weeks after planting. Each flower only lasts a day or two, so you’ll need to check your plants daily when they start blooming.  Saffron doesn’t like too much water. If it is an especially rainy season, consider covering with plastic or moving to a protected area.

Each Crocus sativus flower has three red stigmas, which is the saffron you’ll harvest. Pick the flowers early in the morning, just after they open. Use tweezers or your fingers to gently remove the threads.

To preserve the saffron, dry the threads in a 200 degree oven for seven to ten minutes. Once dried, store them in an airtight container away from light. A little saffron goes a long way.  Just a few threads can flavor an entire dish of paella or risotto.

After the flowers are harvested, the plant will continue growing green leaves through winter and early spring. These leaves feed the corm, helping it produce new baby corms underground. Don’t cut the leaves, they’ll die back naturally in late spring or early summer.

Once the leaves yellow and dry, you can either leave the corms in the ground or dig them up to divide and replant next season. If you planted in containers or crates, store them in a cool, dry place until fall.

Stay in touch with saffron growers around the world. Join the Saffron Email List Saffronnet. This is an international internet network established by the North American Center of Saffron Research and Development for those interested in growing saffron or learning more about ongoing research and other related initiatives.  https://www.uvm.edu/~saffron/pages/saffronnet.html

By Jill Heiman Williams, September 13, 2025

Insects – they’re everywhere! With nearly a million named species, they make up about 90% of all species of animals on the planet and more than half of all living things on Earth. Yet it is estimated that only about one to three percent are truly harmful. Most insects go about their daily business pollinating plants, helping decompose dead material, or ending up as meals for birds, fish, and other creatures – part of nature’s food chain. One big service that a number of insects provide, hidden from most of us, is keeping pest populations down - the good bugs battling the bad ones.  

Natural enemies, also known as beneficials, biological pest control, and good bugs, are the predators that attack, kill, and feed on their prey, the parasites that feed on or inside other insects, killing their hosts, and the pathogens (disease-producing organisms) that can infect and kill the host. While the majority of beneficials are insects, there are also spiders and mites (arachnids), nematodes, and a wide range of microbes. 

Getting to know the good guys is the first step in effective biological pest control. Some common beneficials you may find in the garden include:

• Ladybugs, the rotund little reddish-orange beetle adult and the larval stage, looking like a small alligator, are both predators with enormous appetites.
• Green lacewing adults, the ethereal-looking insects with a slender pale green body and immense golden eyes, aren’t predators at all, feeding on pollen and nectar. But their immature form, also resembling tiny alligators, is a very aggressive predator.
• Soldier beetles are predators of aphids and other soft-bodied insects. Adults are straight-sided beetles about one-half inch long with a red, orange, or yellow head and abdomen.
• Syrphid flies, also known as hover flies, resemble bees. The brightly colored adults are black or brown with yellow-banded abdomens and body markings. Their caterpillar-looking larvae are the predators. Adults feast on pollen and nectar and are considered an important pollinator.
• Spiders are major predators in the garden; some capture prey in silken webs, while others stalk insects across the ground or vegetation or lie in wait and pounce on prey.

Encouraging beneficials in your garden is about the greenest method of pest control you can use.  Like any living creature, these good guys need food, water, and shelter, all generally available in the garden. 

 Here are some ways to attract and keep them around:

• Use diverse types of plants - natives, annuals, perennials, and herbs- to encourage a range of beneficials.
• Use sequentially flowering species to provide nectar, pollen, and shelter throughout the growing season.
• Include plants with many small flowers; they are preferred by many beneficial insects over those with large, single flowers.   
• Create plantings of varied heights in sun and shade to provide food and habitat for different insect species and life stages.
• Maintain groundcovers and coarse mulches for non-flying predators to hide from their enemies.
• Provide water - a shallow dish of water filled with pebbles or gravel and placed in a sheltered area will give small beneficials a safe place to slurp.
• Tolerate low populations of plant-feeding insects and mites so that food is available for the predators.
• Go light on fertilizer; lush new plant growth encourages sucking pests like aphids to reproduce more rapidly than natural enemies may be able to control.
• Avoid the use of pesticides – they don’t discriminate between good and bad bugs.  

These families of plants are attractive to multiple life stages of numerous beneficial insects:

• Carrot (Apiaceae): cilantro, dill, fennel, and Queen Anne’s Lace
• Aster (Asteraceae): coneflower, coreopsis, goldenrod, sunflower, and yarrow
• Bean (Fabaceae): alfalfa, fava bean, and sweet clover
• Mustard (Brassicaceae): mustards and sweet alyssum
• Verbena (Verbenaceae): lantana and verbena

Providing the basics of food, water, and shelter to natural enemies in your garden is pretty easy and has a terrific payback by helping to keep pest populations at a tolerable level.  

By Nanette Londeree, September 6, 2025

Ah, summertime in Marin! Long, sunny days, backyard barbecues, and—unfortunately—those uninvited guests at the picnic table: yellowjackets. These striped speedsters seem to have an uncanny knack for sniffing out your sandwich and making a beeline for your lemonade. But before you reach for the swatter, let’s take a step back and consider the bigger picture. Yellowjackets aren’t just party crashers—they’re also hardworking members of our local ecosystem.

Yellowjackets (Vespula spp.) are often mistaken for honeybees, but they’re actually wasps, and they play an important role in nature. As predators, they help keep populations of garden pests like caterpillars and aphids in check. And while they’re not as famous for pollination as bees, they do contribute by feeding on nectar and transferring pollen as they zip from flower to flower.

That said, no one wants a yellowjacket nest under the deck or an aggressive swarm near the picnic table. Unlike honeybees, which die after stinging, yellowjackets can sting multiple times, making them a painful problem when they set up shop too close for comfort. Fortunately, there are ways to manage these feisty fliers while still respecting their ecological role.

Keep Yellowjackets from Moving In

The best way to deal with yellowjackets is to keep them from settling in your yard in the first place. Here are a few earth-friendly strategies recommended by the University of California’s Integrated Pest Management Program (UC IPM):

• Seal up food sources. Yellowjackets are scavengers, so keep trash cans tightly sealed and promptly clean up food scraps from outdoor meals.
• Limit sugary drinks. Open soda cans and juice boxes are like yellowjacket magnets. Use cups with lids and straws to cut down on their attraction.
• Check for early nests. In spring, queens start new colonies. Look under eaves, in tree hollows, and around wood piles for small golf-ball-sized nests, which can often be removed safely before they grow. A common location for yellow jacket nests is underground, often in abandoned rodent burrows or other cavities. These are harder to find.
• Use yellowjacket traps wisely. Traps can help reduce numbers, but won’t eliminate a colony. If using them, place them away from eating areas to draw wasps elsewhere.

When You Have a Nest Problem

If yellowjackets have already built a nest in a high-traffic area, removal may be necessary—but not a DIY job! These insects defend their nests aggressively, and disturbing them can result in multiple stings. That’s where the Marin/Sonoma Mosquito and Vector Control District comes in. This free public service will assess and remove yellowjacket nests on residential properties, keeping you and your neighbors safe without harming the environment.

Natural Alternatives to Chemical Controls

Manage yellowjackets organically. Here are some safe methods:

• Soapy water spray. A simple mix of dish soap and water can be an effective way to neutralize a small aerial nest when applied at dusk or dawn (but again, proceed with caution!).
• Meat traps and Sugar Traps. Yellowjackets undergo a dietary shift as summer transitions to fall. In the early months, they hunt protein—such as insects and meat—to feed their developing larvae. However, as the colony matures and fewer larvae need feeding, adult yellowjackets pivot to a sugar-rich diet, seeking out ripe fruit, nectar, and even your soda can. A well-placed trap baited with fish or meat earlier in the summer, and then with a sugary lure in late summer, can help manage their numbers effectively.
• Keep compost bins covered. Rotting food attracts yellowjackets, so ensure your compost bin is secured.

Coexisting with Nature

At the end of the day, yellowjackets are just trying to do their job in the grand scheme of the garden. They may be a nuisance at times, but they also help maintain balance in our local ecosystem. By taking simple preventative measures, using environmentally friendly control methods, and calling in expert help when needed, we can all enjoy our summer gardens—without too many uninvited guests buzzing around our burgers.

For more information on yellowjacket management, check out UC IPM’s website (ipm.ucanr.edu) or contact the Marin/Sonoma Mosquito and Vector Control District for assistance.

By James Campbell, August 23, 2025

During a chat with a friend 19 years ago, I heard there was an opportunity to learn more about one of my lifelong passions--gardening. She said after certifying in this UC Marin Master Gardener program, I could not only learn more about plants, soil, and sustainable gardening to improve my own success with plants but gain enough expertise to do outreach to help others use more earth-friendly landscape practices. I was excited to meet others who shared my love of plants and to learn more science-based gardening information and skills during the training course.  I applied and was accepted to the 16-week program. It did not disappoint. In fact, it was so much more than I had anticipated. I met others who had a rich variety of professional and personal backgrounds, but were soon to become lifelong friends and collaborators, talented in many ways, and fun to be with in our shared love of gardens and our community.

What Do Master Gardeners Do? 

The mission is to extend research-based knowledge on home horticulture, pest management, and sustainable landscape practices to the residents of Marin County. 

Founded in 1981 by the University of California Cooperative Extension in Novato, there are currently 344 UC Marin Master Gardeners serving our Marin County community. 

How do Master Gardeners achieve their mission?

• Host hands-on educational workshops that teach our county’s residents how to protect California's natural resources by gardening sustainably.
• Answer questions by email, phone, or in person about how to grow fruit, vegetables, and flowers, and manage pests in the garden
• Provide hands-on demonstrations at school, community, demonstration gardens, and the Marin County Fair.
• Teach horticulture skills to youth and adults through producing videos, public speaking at libraries, and answering questions at farmers’ markets and our free Help Desk, to name just a few of the ways.

How to Apply to Become a Master Gardener?

Applications are available at http://marinmg.ucanr.edu starting July 14, with final applications due on or before September 12. Click on the link to become a Master Gardener. Requirements include being a Marin resident and being available to attend all 16 weeks of in-person and virtual trainings from January 22 to May 7. Trainings start at 9 a.m. on Thursdays and run through early afternoons each week. The program cost is $395, with limited scholarships available.  

Once applications are reviewed, the next step is an interview with each applicant to match the best candidates with the available 2026 training opportunities. Selected trainees are required to be fingerprinted by the Marin County Sheriff before embarking on the training.

It’s All About Classroom, Community, and Collaboration

Once chosen, trainees get a wide scope of topics in the training classroom paired with a range of in-depth homework on a weekly basis. Subjects range from botany, soils, composting, plant pathology, integrated pest management, irrigation practices, growing fruits, vegetables, ornamentals, trees and shrubs, pruning on all types of plants and trees, fire-smart landscaping, and much more. 

Subjects are taught by professionals from our community: UC faculty, nursery professionals, local horticultural experts, and certified Master Gardeners. 

Each trainee is also partnered with a mentor to guide the student through the training classes. Mentors collaborate with and successfully help pair them with county-wide volunteer opportunities to serve Marin residents and further the MMG program. 

The first-year volunteer requirement is 50 hours of service. After that, the yearly requirement is a minimum of 25 volunteer hours and 12 hours of Continuing Education annually.

I hope this information sprouts your interest in these rigorous and fascinating garden education classes and community service opportunities. To learn more details about how to make this opportunity blossom and become a Marin Master Gardener, please go to our website at https://marinmg@ucanr.edu.

Good luck! We look forward to breaking ground with you.

By Jill Fugaro, August 16, 2025

If you’ve ever wrestled with an overgrown fruit tree, you know the struggle—branches reaching for the sky, fruit hiding in a tangled mess, and those pesky suckers popping up everywhere. But don’t worry, summer is the perfect time to get out there with your pruners and give your trees a little mid-season TLC. Done right, summer pruning keeps your trees manageable, encourages better fruit, and makes harvesting a whole lot easier.

Years ago, I used to do all my pruning in winter, figuring that’s when the books said to do it. But then I learned that summer pruning has its own set of benefits. Unlike winter pruning, which encourages a burst of new growth, summer pruning helps slow things down. This means less wild, vertical growth and more energy directed into fruit production.

When it comes to summer pruning, I like to keep it simple. Here’s what I focus on:

1. Water Sprouts and Suckers – You know those tall, skinny shoots shooting straight up from a branch? Those are water sprouts, and they don’t do anything for your fruit. Same goes for the suckers coming up from the base of the tree. I cut them off to keep my tree’s energy focused where it matters.
2. Thinning Dense Branches – If I can’t see a bit of sky through the branches, it’s time to thin things out. Removing a few branches here and there improves airflow, reduces disease, and lets sunlight reach the fruit for better ripening.
3. Shortening Long Branches – If I have a branch stretching too far out, making it tough to reach fruit, I trim it back by about a third. I’m careful not to remove too much at once—keeping at least 80% of the foliage helps prevent sunburn and stress.

Late June through August is prime time for summer pruning here in Marin. By then, the trees have put most of their energy into growing, and fruit has already started to form. I’ve also found that pruning in late summer helps reduce the risk of sunburn since the strongest summer heat has passed.

• Sharp, Clean Tools Are a Must – A good pair of bypass pruners and a sharp pruning saw make all the difference. Dull or dirty tools can tear bark and spread disease.
• Cut at the Right Angle – I always prune just above a bud or lateral branch, angling the cut slightly outward. This encourages healthy regrowth and keeps the tree in good shape.
• Less is More – It’s tempting to go wild with the pruners, but removing too much can stress the tree. I keep my cuts conservative.
• Watch the Weather – I try to prune on dry days to minimize the risk of fungal infections.

Every time we prune, we’re influencing the tree’s hormone balance. The tips of branches hold growth hormones (auxins), so when we remove those, the tree redirects its energy elsewhere. Summer pruning helps keep trees compact and productive, while winter pruning encourages new shoots to take off in spring. Knowing when and how to prune makes all the difference.

From my own experience and what the experts say, these are the best fruit trees to prune in summer:

• Apples & Pears – Keeps them a manageable size and improves fruit quality.
• Peaches & Nectarines – Thinning out excess growth helps with air circulation and prevents fungal diseases like peach leaf curl.
• Plums & Apricots – Good airflow helps prevent brown rot, which can be a real problem in our coastal climate.
• Cherries – Summer pruning helps prevent bacterial canker, which thrives in damp conditions.

Summer pruning may seem like an extra chore, but trust me, it pays off. A little effort now means healthier trees, tastier fruit, and an easier time harvesting later. So grab your pruners, step outside, and give your trees some love. Your future self (and your fruit bowl) will thank you!

By James Campbell, August 9, 2025

With their timeless beauty and grace, roses are often considered jewels of the garden.  They also have the reputation for being persnickety plants that are high-maintenance and heavily dependent on chemical fertilizers and pesticides. Today’s gardeners are looking for easier and gentler ways of growing America’s national flower, and ask, can you have gorgeous rose blooms on plants that are bountiful and healthy AND be kind to the environment at the same time? The answer is a resounding YES! Grow your roses and all your other garden plants the Earth-friendly way.  Using sustainable processes that mimic Nature, you can create a great-looking garden that’s healthier for you, your family, your pets, and the environment! 

The key elements for this kinder approach to growing roses are to choose the right varieties for your location, build and maintain healthy soil, water wisely, promote biodiversity, and use integrated pest management.  

Choose the right varieties for your location – When shopping for roses, look for varieties that are well-suited to your garden’s microclimate and have proven to resist disease. The Marin Rose Society website has a list of roses that do well in our environment. Plant in a place that gets a minimum of six hours of sun each day, is protected from wind, and has adequate space to spread out. 

Build and maintain healthy soil - Like all plants, roses thrive when grown in healthy, living soil, rather than relying on chemical fertilizers that can harm soil life and pollute waterways. Feed the soil with compost, aged manure, or organic mulch. These materials provide a slow and steady supply of plant nutrients that improve soil structure, promote movement of air and water, and are a good home for plant roots and soil organisms. 

Water wisely - Deep, infrequent watering that encourages the development of strong root systems is key to effective watering. Drip irrigation or soaker hoses are ideal, delivering water directly to the soil without wetting the foliage. Water early in the morning to reduce evaporation and allow leaves to dry if they do get wet, reducing the chance of disease.

Promote biodiversity - A wide variety of flowering plants, including natives, perennials, annuals, and herbs, supports diversity of soil microorganisms, and provides nectar and habitat year-round for beneficial insects like ladybugs, lacewings, and parasitic wasps that prey on common rose pests. Let parts of your garden grow a little wild, with areas of undisturbed ground, leaf litter, or flowering weeds like dandelions that can support a variety of life forms. 

Use integrated pest management – Whether it’s aphids or spittle bugs, earwigs, or cucumber beetles, you likely don’t want these pests on your roses or other garden plants.  Using integrated pest management (IPM), a holistic, ecologically based approach, you can prevent pests entirely or reduce them to levels you can live with. 

In a healthy ecosystem, natural enemies keep pest populations in check (think ladybugs munching on aphids). Predators, parasites, and pathogens (disease-producing organisms) are the primary groups of natural enemies (also called biological control agents). These include many species of birds, mammals, amphibians, and reptiles,  as well as predatory insects and spiders, and pathogens specific to pests, such as Bt (Bacillus thuringiensis) for many caterpillars. 

Take Nature’s approach and invite these helpful pest controlling creatures into the garden by providing them with food (seeds, berries, nuts, fruits, nectar, pollen, and foliage), water for drinking and bathing (anything from a cement birdbath to a depression in a stone), protection from predators and weather (dense shrubs, evergreens, rock piles, and wooded areas), and places for raising their young (mature or dead trees, dense shrubs, burrows, or even home-made nesting boxes). And do so while being gentle with your garden-nurturing your soil, using organic materials, and avoiding chemicals from synthetic fertilizers and pesticides that may harm wildlife.

It’s actually pretty easy to enjoy your beautiful roses grown the Earth-friendly way!

By Nanette Londeree, August 2, 2025

As you wander beneath Marin County’s stately white oaks, such as valley and blue oaks, be aware some little troublemakers are on the move. The Mediterranean oak borer (Xyleborus monographus), a beetle scarcely bigger than a peppercorn—about 3 millimeters long, or one-eighth of an inch—is quietly carving its way into our beloved oaks.

Where it came from and where it’s been found

This beetle hails from Europe, the Middle East, and North Africa—classic Mediterranean territory. It was first spotted in California in 2019 in Napa County. Since then, it has been reported in Lake, Sonoma, Mendocino, Sacramento, El Dorado, and Yolo counties—and as of  May 2025, in Novato, here in Marin.

What trees it targets

The Mediterranean oak borer (MOB for short) mostly attacks native oaks, particularly valley oak (Quercus lobata) and blue oak (Quercus douglasii). It seems to prefer trees already stressed from drought, injury, or age. In some areas, black oaks have also been affected.

How it does its damage

MOB is a type of ambrosia beetle, and it doesn’t eat the wood itself. Instead, it bores into bark and lays eggs in tunnels called galleries. There, the beetle cultivates fungus—specifically, ambrosia fungi—which serves as food for both adult beetles and their larvae. The problem is that fungus spreads through the tree’s tissues, disrupting its ability to move water and nutrients. Over time, this fungal invasion, combined with damage from tunneling, can weaken and eventually kill the tree.

The beetle can produce two or more generations each year in California’s warm climate, so infestations can escalate quickly. The spread is accelerated by females flying to other trees. 

Signs to watch for

Keep your eyes on the canopy. One of the earliest signs of MOB activity is a single branch that wilts or drops leaves while the rest of the tree looks fine. You might also notice fine sawdust collecting in bark crevices or on the ground below. Tiny, round exit holes—about the size of a pinhead—may appear on the bark, sometimes with dark staining or oozing sap.

If you cut into an infested branch or trunk, MOB galleries appear as tightly packed, fan-like or trellis-shaped tunnels—unlike the rounder or more scattered galleries left by native beetles.

What to do if you suspect it

If you think your tree might have MOB, don’t wait. Consult a certified arborist familiar with invasive pests.

Early detection matters, and proper handling of infested material is critical to slowing the spread. If a tree is confirmed to have MOB, the recommended steps include:

• Do not transport firewood—MOB larvae can hitch a ride to new areas.
• Chip infested wood into small pieces (1–3 inches).
• If chipping isn’t possible, burn the wood locally or cover it with soil to prevent the escape of beetles.
• Letting cut wood dry thoroughly in the sun can also kill larvae.

Research on chemical treatments are underway, including those to manage MOB and reduce fungal infection. Until treatment options are confirmed effective, prevention and sanitation are the key tools in the fight.

What can gardeners do?

The best way to protect your oaks is to keep them healthy and well-maintained. Avoid injuring tree trunks with tools. Mulch to preserve moisture and reduce root stress. Water deeply during dry spells, especially for young or vulnerable trees.

And most importantly, stay observant. Check your trees regularly, especially in late spring and early summer, when beetle activity is at its highest. If something looks off, consult an arborist.

The Mediterranean oak borer may be tiny, but with your help, we can keep Marin’s oaks standing tall. For more information, https://ucanr.edu/sites/default/files/2024-09/330538.pdf

By James Campbell, July 26, 2025

Seems like every time I go to the nursery, there are new things to buy – and I’m not talking about the plants. This is especially true when it comes to soil amendments. Some of these packaged materials are helpful. Worm castings are packed with millions of beneficial microbes. Leaf mold boosts nutrients. Biochar, a charcoal-like
substance, improves soil fertility and carbon sequestration. Aged manure from cows and other beasts conditions the soil, improves drainage, and provides macro and micronutrients. Compost, made from decomposed garden and kitchen scraps, enriches soil structure, aeration, and water-holding capacity. 

These are tried and true, research-backed, science-tested amendments that can make a real difference in the health of your soil and garden. 

But what about the other stuff? The vermiculite? The perlite? The peat? What is that stuff, and do you need it? Is it healthy for the garden – and the planet?

Let’s start with peat. Peat moss is a fluffy, absorbent, lightweight brown material you shovel into soil to increase water retention and acidity. For that reason, it has been a mainstay for gardeners growing acid-loving plants like blueberries, hydrangeas, and camellias. 

Peat moss comes from peat bogs. These are large wetland areas where decaying plant matter called peat has accumulated extremely slowly – just a millimeter a year – for 12,000 years. For you armchair paleontologists, that’s about the time the last ice age was ending. 

But here’s the kicker: peat bogs comprise just 3% of the planet, but they store a third of the world’s carbon. Incredible! That’s more carbon than all the planet’s forests combined. In fact, only the world’s oceans sequester more carbon than the peat bogs. As a result, they are absolutely critical to the health of the Earth’s carbon cycle – the process that regulates the Earth’s climate and supports life. 

I think you know where this is going. Every time peat moss is harvested, carbon is released, habitat is destroyed, C02 is unleashed into the atmosphere, and the risk of a warmer Earth rises. The salt in the wound is that it takes a few millennia for the peat to regenerate. Bottom line? Peat moss is a non-renewable resource. And the harm that could be unleashed if the bogs were heavily stripped is unthinkable. 

It should therefore come as no surprise that some countries have banned the sale of peat moss. Question is, should you join them? 

That’s up to you, but to help nudge you into making the Earth-friendly decision, please consider some of the excellent alternatives. Coconut coir is fast becoming a peat moss alternative because it provides many of the same benefits. Adding compost, pine needles, and oak leaves gradually increases soil acidity.

Next, let’s take a peek at those sacks of vermiculite, the small brown flecks you often see in potting soil, and perlite, the companion white flecks. Vermiculite is a
mineral that improves water and nutrient retention in soil and enhances aeration, which is critical for healthy roots. Perlite excels at improving drainage, which is good for plants that don’t like wet roots. 

These common potting soil bedfellows sound like they were stamped out of a machine, but they are actually natural materials. Vermiculite is a mica-type mineral that’s heated at high temperatures, and perlite is a naturally occurring volcanic glass. Are they healthy for soil? Yes, they work extremely well together in soils meant for starting seeds. Are they an Earth-friendly choice? 

Perlite is a non-renewable resource, although to date, less than one percent has been mined. Vermiculite, on the other hand, requires significant energy for the mining and processing. I guess you’d have to say it’s a mixed bag, but it seems to me that the benefits outweigh the negatives.

Finally, what about those innocent looking bags of sand? Should you mix it into your clay soil? No. Resist the urge. Why? Because mixing clay soil with sand creates
something akin to concrete. Oops!

By Marie Narlock, July 19, 2025