Chill Out! Cold Stratification for Native Plants

 

Cold stratification is an important step for growing many native plants in USDA Hardiness Zone 7. This process mimics winter conditions, helping seeds break dormancy and ensuring they germinate at the right time in spring. In the Treasure Valley area, which is situated in Ecoregion Level III 12 (Snake River Plain) and borders Ecoregion Level II 10.1 (Cold Deserts), you have a unique opportunity to cultivate a variety of native plants. Whether you’re interested in wild sunflowers, asters, goldenrods, lupines, purple coneflowers, milkweed, or penstemon, following these steps will help you successfully propagate these beautiful species in your garden.

Understanding the Ecoregion

Ecoregion 12 features a mix of desert and semi-arid environments, characterized by cold winters and warm, dry summers. The region's soils vary from sandy to clayey, which influences the native plant communities that thrive here. Plants in this area have adapted to withstand drought and temperature extremes, making them well-suited for home gardens that aim to support local wildlife and conserve water.

Starting Seeds Indoors or in a Greenhouse

Starting your native seeds indoors or in a greenhouse allows you to control conditions better. Follow these steps:

1. Gather Your Seeds: Collect seeds from native plants in the fall, ensuring they are fully mature and dry.

2. Prepare Your Pots: Use seed-starting pots filled with a seed-starting mix. Make sure the pots have drainage holes.

3. Moisten the Medium: Lightly moisten the seed-starting mix so it's damp but not soggy.

4. Cold Stratification:

• Option A: Directly in Pots: Sow the seeds in the pots, covering them lightly with soil only if they don’t require light to germinate. If they do need light, surface sow seeds and place the pots in the refrigerator for 4-12 weeks. Keep the pots in a plastic bag to retain moisture.

• Option B: Pre-soaking: Alternatively, mix seeds with a moist medium like sand or peat moss in a zip-top bag, refrigerate for 8-12 weeks, and then surface sow them in pots after stratification.

5. Move to Light: After the stratification period, move your pots to a well-lit area or greenhouse. Ensure they receive plenty of light but avoid direct, harsh sunlight at first.

6. Water Regularly: Keep the soil consistently moist (but not waterlogged) as the seeds begin to germinate.

7. Transplanting: Once the seedlings have a few true leaves and the danger of frost has passed, transplant them into your garden or larger containers.

Starting Seeds Outdoors in your garden or raised beds

1. Gather Seeds: Collect seeds in the fall from mature plants, ensuring they are fully dry. This timing allows you to utilize natural seasonal changes for germination.

2. Prepare the Planting Area: Choose a well-draining spot in your garden or raised beds. Loosen the soil and remove any weeds or debris.

3. Surface Sow: Scatter the seeds on the surface of the soil. Many native seeds benefit from light exposure to germinate, so avoid covering them deeply. If the seeds require some soil coverage, lightly sprinkle a thin layer of soil over them.

4. Watering: Gently water the area to help settle the seeds into the soil without washing them away. Ensure the soil stays consistently moist, especially during dry spells.

5. Winter Conditions: As winter arrives, the seeds will experience natural cold stratification, which helps break dormancy and prepares them for germination.

Benefits of Cold Stratification By cold stratifying your seeds, you help ensure healthy germination and align plants with their natural growing cycles. This process also supports local ecosystems by enhancing biodiversity, stabilizing soil, and conserving water.

With a little preparation, you can successfully cultivate beautiful native plants that thrive in your region, including wild sunflowers, asters, goldenrods, and lupines. 

Happy gardening!

Scotch Thistle: Spotting & Stopping this invasive in Idaho Landscapes

Have you noticed a massive, silver-green giant creeping into nearby pastures, roadsides, or even the back corners of your home garden? Scotch thistle (Onopordum acanthium) is making an aggressive push across Idaho landscapes, and this highly invasive weed requires early intervention.

Originally brought to the United States in the 1800s as a Mediterranean ornamental plant, it quickly jumped the fence. Today, it is an officially listed Class B Noxious Weed in Idaho, Oregon, and Washington. If left alone, it can easily form dense, virtually impenetrable stands that choke out native forage, block access for wildlife, and cause a major headache for homeowners.

Knowing the Lifecycle: Year One vs. Year Two

The secret to managing Scotch thistle is understanding how it grows. It operates primarily as a biennial plant, adapting its growth strategy based on the local environment:

• Year One (The Rosette): The plant spends its first year low to the ground, focusing energy on building a tough taproot. It forms a wide rosette of gray-green, velvety leaves covered in a thick mat of woolly hairs and sharp yellow spines. These rosettes can spread up to 2 feet wide.

• Year Two (The Giant): In its second year, the thistle bolts. It shoots up a heavily branched, winged stem that can tower over 8 feet tall and 6 feet wide. Globe-shaped, dark pink to lavender flowerheads emerge at the branch tips in mid-summer.

Why Is It Such a Problem?

A single, healthy Scotch thistle plant is capable of producing 8,400 to 40,000 slender, plumed seeds. These seeds are easily caught by the wind, hitch a ride on moving wildlife, or travel via contaminated soil, gardening equipment, and hay.

Once it establishes a foothold in wet meadows, dry rangelands, or disturbed garden soils, it quickly forms thick patches. Its formidable, spiny armor physically blocks animals from grazing and prevents access to waterways.

How to Control Scotch Thistle in Your Space

Tackling an infestation requires an integrated management approach combining mechanical, cultural, and targeted chemical methods.

1. Manual and Mechanical Removal

• Dig it out early: Small infestations are easiest to manage when the plants are still in the low rosette stage. Use a sharp shovel to slice the taproot completely below the soil surface.

• Gear up properly: The sharp spines are no joke! Always wear heavy-duty leather or chemical-resistant gloves and thick protective clothing to avoid painful punctures.

• Time your mowing: For larger patches, mowing can prevent seed production, but timing is everything. Mowing too early causes the plant to simply recover and flower closer to the ground. Mowing too late means cut flowerheads left on the ground can still successfully release viable seeds.

• Bag and trash: If the thistle has already started blooming, bag up and discard the cut flowerheads in the trash rather than composting them.

2. Cultural and Biological Methods

• Establish Competition: The single best long-term defense against thistle seeds is a dense, well-maintained lawn or pasture. Healthy, thick turfgrass or native groundcover will naturally outcompete invading seedlings.

• Managed Grazing: While there are currently no approved biological insect controls for Scotch thistle, goats will readily graze the prickly flowerheads, and sheep will sometimes feed on the younger rosettes.

3. Herbicide Control

When physical removal isn't practical, a targeted herbicide treatment may be necessary. Applications are generally most effective when sprayed during the active spring growth phase before the plant bolts. Remember to follow all pesticide safety protocols: wear proper protective clothing and avoid spraying during windy or excessively hot conditions to prevent chemical drift and volatility.

For specific chemical recommendations and timing tailored to your local county, consult the Pacific Northwest Weed Management Handbook or contact your local county noxious weed coordinator.

Remember Your Legal Obligations

Because Scotch thistle is on regional quarantine lists, it is illegal to buy, sell, transport, or distribute the plants, seeds, or wildflower mixes containing them. Keeping our boots, tools, and tires clean after visiting infested areas is a simple step that goes a long way toward protecting Idaho's beautiful open spaces.

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Resources & Further Reading:

• Identification and Management of Scotch Thistle — Oregon State University Extension Catalog

• Noxious Weed Search: Scotch Thistle — Washington State Noxious Weed Control Board

• University of Idaho Extension — Landscapes and Lawns

Fungus Gnats- Are these flying around your indoor plants?

Tiny flying pest in my houseplants

fungus gnats life cycle

Fungus Gnats can become a problem on potted house plants, especially during the holiday season because we are bringing in flowering plants from nurseries, big box stores, as well as receiving as gifts. They are difficult to control because of their tiny size and life cycle.

 Here are some effective ways to treat them:

Let the potting soil dry out between watering. The "dry" surface is less attractive to females who are depositing eggs, and if eggs are deposited, they fail to hatch because of lack of moisture. This cultural approach can be very effective.

 Sticky traps really work!

Fly tape or sticky traps. The gnats are drawn to the yellow color. No need to fall for the trap of buying anything with pheromones either. Simply a yellow sticky trap.

Tiny larvae on the soil in houseplant pot

Bt is available (Sold under the names Gnatrol, Mosquito Bits) is very effective in controlling the larvae, is not harmful to beneficials, and approved for organic growers. So easy to use - just sprinkle on the soil in the pot!  Nematodes are also available should you desire biological control.

In severe infestations, you may consider washing the roots and re-potting in fresh soil, or simply spraying a light application of indoor houseplant insecticide. When you use any insecticide, be sure to read and follow all label instructions!  Finish by creating a tent over your plant and secure the bottom with a rubber band. Watch for a couple of weeks to see if there is still activity.  Don't worry about watering because you have created a little greenhouse but keep the plastic from touching the leaves. 

Amaryllis Magic: Winter Cheer

Winter is a magical time for indoor gardening, and the amaryllis stands out as one of the most stunning winter-blooming plants. Known for its impressive, large flowers that can range from pristine white to deep red, the amaryllis adds vibrant color to holiday decor and offers a rewarding gardening experience.

To begin your amaryllis journey, plant the bulb in the fall, ideally in late October or early November. This timing allows the plant to bloom beautifully during the winter months. 

Select a healthy bulb from a reputable source and choose a pot that is about 1-2 inches wider than the bulb. Use a well-draining potting mix, and when potting, ensure that the top one-third of the bulb remains above the soil to prevent rot. Place the pot in a warm, bright location—around 70°F (21°C) is ideal. Water thoroughly after planting, making sure excess water can drain away.

As the plant grows, thick, sturdy stalks will emerge, followed by large, trumpet-shaped flowers. These blooms can last for several weeks, creating a cheerful atmosphere in your home. To maintain the plant’s appearance, remember to turn it regularly to ensure even light exposure and prevent it from leaning toward the light source.

Once the flowers fade, proper care for the foliage is essential. Allow the leaves to die back naturally, as they play a crucial role in photosynthesis, storing energy in the bulb for future growth. When the leaves turn yellow and begin to wither, you can cut them back to the bulb.

For those looking for an easier option, waxed amaryllis bulbs have become increasingly popular. Coated in colorful wax, these bulbs require no soil or potting and can simply be displayed in bright, indirect light. The wax helps retain moisture, allowing the bulb to grow without the need for watering. While waxed bulbs are typically intended to be discarded after blooming, they can be revived with a bit of effort.

After the flowers fade, you can remove the wax and any wire from the bulb. If the bulb is still firm, you can plant it in a well-draining potting mix, treating it like a traditional amaryllis bulb. Plant it with the top one-third exposed above the soil, place it in a warm, bright location, and resume regular care. With proper attention, the bulb may produce new growth and bloom again.

If you choose to save a traditional amaryllis for next year, give it a resting period of about eight weeks in a cool, dark place after the blooms fade. Repot the bulb in fresh soil, lightly water it, and return it to a warm, bright location to stimulate new growth.

With the right care, both traditional and waxed amaryllis bulbs can bloom again, bringing joy and beauty to your home year after year. Understanding their unique needs—from planting in the fall to post-bloom care—allows you to enjoy the spectacular flowers of the amaryllis long after the holiday season has passed, making it a cherished addition to your indoor garden.

Know How to Grow - Become a 2C Master Gardener!

Have you ever been elbow deep in dirt and wondered why or what is happening to your plant? Do you wish you knew more about your soil and how to make your plants happier? Are you looking for research-based information that will allow you to reduce pesticide use and help work together with beneficial bugs? If you said yes to any of the above, YOU ARE NOT ALONE! 

Become an Idaho Master Gardener in Canyon County - learn the art and science of horticulture! Our series of classes provide you with a variety of ways to improve your gardening skills...and share your passion and knowledge with others. Do you want to connect with other gardeners in your community? Then you will not want to miss this opportunity! 

Classroom learning

The Idaho Master Gardener program consists of TWO phases:

  

Phase One: This 50 hours of classroom training provides a stress-free, engaging learning environment. Fresh coffee, water, and tea at each session is also a great perk! Maybe even food...

Phase Two: After the classroom training, you will complete 30 hours of practicum education via volunteer service. 

Hands-on field trips

2cTurf & Team site visit

You will also have the opportunity to choose from focus areas in which you would like to complete your hands-on experiences with various teams: Tree & Turf, Integrated Pest Management, Junior Master Gardener, Outreach, Plant Sale, and Social Media. Teams build comradery and skills. FUN, too!

Start Date: University of Idaho Extension, Canyon County (Caldwell, ID) Idaho Student Master Gardener classes start September 10, 2025 and run through April 15, 2026.  Classes are held on every other Wednesday morning from 8:30am-12pm at the University of Idaho Research & Extension Center, 1904 E. Chicago Street, Caldwell, Idaho 83605.  

Cost: The cost for the 2026 Canyon County Master Gardener program is $280 to be paid by 8/29/2025 (scholarships and payment plans are available).  This cost includes a handbook, a soil test, several hands-on labs, field trips, a background check, a Master Gardener t-shirt and a name badge at the end of the course.

Application Deadline: The deadline to apply for the Canyon County Idaho Master Gardener program is August 15, 2025. Get your spot early as space is limited in class.  We at the U of I Extension want everyone to be comfortable and safe while learning about horticulture. We offer in-person classes (while spots are available).  Complete your application today!

IPM Scouting Walk

The Idaho Master Gardener program is NOT a gardening class, rather a VOLUNTEER and DEVELOPMENT PROGRAM.  The University of Idaho Master Gardener Volunteer Program serves as an educational and volunteer organization. All course participants must be willing and able to contribute 30 hours of practicum volunteer service prior to September 30, 2026, to complete certification. There will be plenty of time and lots of opportunities to complete your hours. We look forward to having you join our team.

Helping people grow is what we do. 

Apply here 👉https://forms.office.com/r/E84saNVKKatext or https://bit.ly/2025-26_MGapplication.

Call us today 👉  (208) 459-6003 

Follow us here 👉

Facebook @2CMasterGardeners   

 Instagram @2cMasterGardeners 

Protect your plants from Powdery Mildew

Figure 1: PM on Tomato

 Powdery mildew is a fungal disease that affects a wide variety of plants. The affected plants have a dusted-with-flour appearance with white to gray powdery spots on the surface of leaves and fruits (Fig 1). It causes cosmetic damage, and defoliation and decreases the quantity and quality of fruit (Fig. 2).

Disease and Development 
There are many different species of (Powdery Mildew) fungi. Most species only attack specific plants in the same or closely related plant families.

Figure 3: PM on roses

For example, powdery mildew on roses does not spread to grapes.

Powdery Mildew fungi overwinter in buds, twigs, bark, and plant debris. Their spores are carried by wind to new hosts. Low relative humidity during the day favors spore dispersal.

Fig 2: PM on grapes

The optimum conditions for spores to germinate are temperatures between 68 to 77°F and high relative humidity (> 70%). Powdery Mildew spores can germinate in the absence of water and can infect in arid conditions (40% humidity). Water on plant surfaces can kill or inhibit germination. Spores and fungal growth are sensitive to extreme heat (above 90°F) and direct sunlight. Shady conditions are favorable for PM development.

Management
The disease triangle is a useful tool to understand and manage diseases like Powdery Mildew (Fig. 3). The severity of Powdery Mildew infections is a function of the presence of the pathogen, the host susceptibility, and the environment. Powdery Mildew can be managed by good cultural practices.   

Fig 3: The Disease Triangle

The best control is to plant only resistant species or cultivars. Avoid excess fertilizer since plants with abundant succulent tissues are more susceptible to infection. The fungi can be eliminated by removing and burning all infected plant tissues and debris. Tools must be disinfected after use.

Another good control method is making environmental conditions less favorable for the disease. Avoid dense canopies by proper plant spacing and pruning to provide good air circulation, reduce humidity and increase sunlight penetration. Plants should not be planted in poorly drained soils or shady damp areas.

Overhead watering of the leaves during the day and when humidity is low can reduce infection. Water washes spores off the plant and inhibits its germination. This control method is not recommended for vegetables since it may contribute to other pest problems.

Powdery Mildew seldom needs chemical control in residential plantings, but it may be warranted in commercial plantings of susceptible crops like grapes and cucurbits. Chemicals are most effective when combined with cultural control. They should be applied before the disease symptoms appear. Further spread may be stopped or slowed with chemical treatment. Materials like horticultural oil or neem oils have a low environmental impact. Apply every 7 to 14 days throughout the season. Do not apply to drought-stress plants when the air temperature is above 85° nor within 2 weeks of a sulfur spray. Wettable sulfur is very effective in preventing infection. Like oil application, it should not be applied when the air temperature is over 90° nor within 2 weeks of an oil application.

Blueberries in Idaho - it's work...and worth it!

 Craving fresh blueberries? It is possible to grow them here in Idaho.
 Here's how:

• Blueberries are compact flowering bushes that bear round bluish fruit.
• They require full sun and only like moist acidic soil. Soils in Southwestern Idaho are commonly alkaline, so you must  use an acidic planting mix. 
• They can be planted in a landscape with amended soil or also successfully grown in a container. 

Pruning, Maintenance and Fertilizer

Blueberries require little pruning; however, maintenance is required in terms of fertilization and sulfur. You’ll need to be patient.  For the first year you’ll need to strip off all the blossoms so the plant can use its energy to grow strong healthy canes for increased production. 

If planting in a container, you’ll need to monitor water closely because pots dry out quickly. Blueberries like moist well drained soil but not soggy conditions.  Mulching will help keep the soil moist and limit the growth of weeds.  After the first 2 springs, you’ll want to prune off older canes to encourage new growth and fertilize with an alkalizing fertilizer (21-0-0)

Which variety to choose?
There are many recommended cultivars which will grow in Idaho. Depending on bloom time,

hardiness and height, make your choice from two different cultivars to insure pollination.

Whether you chose to grow a Northern Highbush, Southern Highbush, Rabbiteye, Lowbush

or Half-High, your plant will produce more and larger berries when cross pollinated.

There is still time to get your blueberry plants from your favorite local nursery

Quick tips and things you'll need:

Acid Loving Potting Mix

Soil Sulfur

Ammonium Sulfate 

Acid Plant Fertilizer

Bird Netting (the birds like blueberries as much as humans)

Plant in full sun

Protect with bird netting
Choose two different cultivars for cross pollination
Replace native Idaho soil with acid loving planting mix
Fertilize with 21-0-0
Fertilize with soil sulfur
Remove blossoms 1st year and additional canes 1st two springs

Blueberry Syrup Recipe

2 cups fresh blueberries                            

¼ cup raw stevia or equivalent                                  

½ cup water                                             

2 teaspoons cornstarch

1 teaspoon lemon juice

1 tablespoon creme de cassis (optional)

Place Blueberries in a sauce pan on the stove.  Mix water and cornstarch together until dissolved add to blueberries.  Cook over medium heat until berries start to pop.  Use the back of a spoon to mash the berries and boil 1 minute.  Add the stevia, lemon juice and Crème de Cassis.  Store unused portion in refrigerator for up to about a week.  This sauce can also be added to plain yogurt or ice cream. 

Vertical Gardening: Grow Up, Not Out

If you’ve ever felt limited by a small yard or patio but want to grow your own plants, vertical gardening is the perfect solution. Utilizing vertical space instead of ground space, a vertical garden allows you to grow flowers, fruits, and vegetables in a compact and efficient way. Also known as green walls, living walls, or eco walls, vertical gardens are now even being used in farming for crops like lettuce, tomatoes, and strawberries. With all the advantages of vertical gardening, why grow out when you can grow up? 

Vertical gardens can thrive in a variety of settings. Whether you have a sunny balcony, a shaded patio, or a compact backyard, there’s a setup that will work for you. Some great places for a vertical garden include decks, porches, patios, small backyards, and even indoor living spaces with proper lighting.

Choosing Your Containers and Structures
A vertical garden can be built using many different materials, making it a fun and customizable project. Stacking containers are ideal for strawberries and herbs, while pallets work well for growing lettuce, herbs, and small flowers. Trellis fencing is a great choice for supporting squash, cucumbers, and baby butternut squash. Tripods or teepee shapes are perfect for supporting peas and beans. Upcycled materials, such as old fencing, blank walls, and repurposed containers, can be transformed into a unique and sustainable vertical garden.

How to Start Your Vertical Garden
To begin, choose a suitable container based on the plants you want to grow. Use a high-quality, well-draining soil mix to ensure proper plant growth. Decide whether you want to grow flowers, fruits, vegetables, or a combination of all three. Set up a watering system, such as a timed drip system for efficiency or manual watering for hands-on care. Position plants based on their light requirements to ensure proper growth, and plan for shade by strategically placing taller plants to protect lower-growing ones. Different plants require different fertilization schedules, so be sure to research your choices before applying nutrients.

Maintaining Your Vertical Garden
To keep your vertical garden thriving, regular maintenance is key. Fertilize plants as needed to ensure they receive the proper nutrients. Monitor the function of your watering system and adjust it as necessary. Regularly prune and trim plants to keep them healthy and encourage new growth. Train climbing plants by using ties or trellises to guide them upwards. Keep an eye out for pests and take preventive measures to protect your plants. Make sure your plants get enough sunlight and are shielded from strong winds to prevent damage.

A vertical garden opens endless possibilities for growing a lush, thriving green space in even the smallest areas. With a variety of containers, structures, and plant choices, you can customize your vertical garden to be just right for you. Plus, repurposing materials and containers makes it a sustainable and cost-effective gardening option. At the end of the growing season, you can reuse many of the materials for the next year, making it an investment in both beauty and practicality. So why limit yourself to traditional gardening when you can take your garden to new heights? Start your vertical garden today and enjoy the benefits of growing up, not out!