December 2015
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News for Norther Colorado and the world

Wednesday, December 2, 2015

Master Gardeners: garden green plus saving seeds


Green Gardening: Alternatives to

Commercial Insecticides and Herbicides

By: Kathi Taylor
Colorado State University Extension Master Gardener in Larimer County

Organic or “green” gardening is the goal of many gardeners. However, with the abundance of moisture this spring and summer, weeds are popping up everywhere and potentially harmful insects are prolific—what’s a gardener to do? Before reaching for a familiar bottle, consider greener alternatives.

Planting and cultural practices can help alleviate many issues in garden beds. Initially, prepare soil well, adding compost and aged manure in the fall. On established beds consider sprinkling a 1-2” layer of these materials after plants die back in the fall. Next spring, space plants more closely, install drip irrigation, and side dress with organic fertilizer. And don’t forget to mulch! As heat ramps up, a thick layer of mulch will prevent many weed seeds from germinating, so hand weeding can be effective (and good exercise). These practices will reduce water use, weeds, and fungal disease. “Green” culture promotes healthy plants, able to ward off insects and disease.

Does your garden have weeds popping up in paths, hardscapes and gravel areas? Try clipping the stems at ground level and dousing the weeds with boiling water. While this won’t permanently kill perennial weeds, it will slow down growth. If walking around with boiling water isn’t your “cup of tea,” use a hefty spray of white vinegar—just be very careful, as it is caustic. All methods for killing weeds, including commercial preparations, work best on young plants. Also, don’t forget about digging up weeds. That burly weedy specimen unnoticed until now may be best dealt with your favorite weeding tool. If weeding really isn’t your favorite outdoor activity, preventing weeds from going to flower (thus setting seed) is a big step in reducing future weed problems.

Are aphids attacking your deciduous trees, spider mites infesting junipers and psyllids causing yellowing and distorted stems on tomatoes? Consider using the garden hose and a strong jet of water. If this doesn’t work, try horticultural soap. Soft bodied arthropods such as aphids, mealy bugs, psyllids and spider mites are susceptible to soaps. Although repeat applications may be necessary, most pollinators and predatory insects will not be harmed. Depending on climatic conditions, including temperature, wind and humidity, plant damage is a possibility. To reduce the chance, spray on cloudy days, early or late in the day, dilute the soap and be aware that homemade soap sprays exhibit more potential for damage.

If leafhoppers are careening around the garden, scale insects are moving up and down stems and whiteflies are floating through the air, you know the garden is a veritable smorgasbord for bugs. It’s not enough that the gardens are being eaten; powdery mildew, the bane of a damp and humid summer, is silvering the foliage. Grab horticultural oil and take charge. These oils, applied as a foliar spray, are useful as a fungicide and insecticide. If applied properly, oils display low toxicity to animals and humans. Household baking soda, mixed with horticultural oils, was found to have an effect on powdery mildew, but research is on going with this potential solution.

Are earwigs, pill bugs, and slugs eating the foliage and fruit from garden ornamentals and vegetables? Diatomaceous earth is a natural pesticide. Made from the ground shells of tiny fossil sea creatures, it is non-hazardous to humans and animals; however, it is a very fine dust. Wear dust masks and protective eyewear when spreading. Diatomaceous earth works by destroying the waxy coating on insects, causing them to dehydrate and die.

Have weeds in the lawn? Think about a natural alternative to conventional herbicides. Corn gluten meal, a byproduct of corn processing, is a natural herbicide that kills crabgrass and annual weeds, if applied in early spring—and it adds nitrogen to green up the turf. Applied correctly, it prevents normal root growth in seedlings.

Considering alternatives to commercial pesticides may take more thought and definitely more patience. Yet, each time a wise environmental choice is made, the earth benefits and you are “going greener. ”

For more information on the above topics go to the CSU Extension website at and consult Fact Sheets #5.547 and #5.569.

Tips for Successful Seed Saving

By: Annie Lindgren
Colorado State University Extension Master Gardener in Larimer County

  • Self-pollinated plants are the easiest to save seeds from, because there is less worry about cross-pollination. Plants in this category include beans, endive, lettuce, peas, tomatoes and amaranth.
  • Plants that rely on insects or air for pollination must be separated from other variations of the same species by up to a mile if you plan to collect seeds from them; otherwise they will cross pollinate and the produced seed will not be like the parent plant. Examples include squash and melons.
  • Do not save seeds from hybrid plants, as the plants grown from the seeds will vary greatly from the parent plant.
  • It is best to collect seeds from the first 1/3 of the crop (not the first to ripen, or the last), and make sure to collect seed from the best looking plants.
  • Extract wet seeds from the fruit after it ripens and before it rots. Mash the fruit up in a bucket, and add water. Let ferment for up to three days, stirring daily. After the third day, fill the container with more water, and the fertile seeds will drop to the bottom.  Gather and rinse off the good seeds and let them dry up to five days.
  • Dry seeds should be taken when the seed heads or pods are dry, but before they drop seeds on the ground. Dry them on a drying rack (nylon window screens work great) and sift them through a screen to get rid of debris.
  • Store dried seeds in an envelope or plastic bag in a cool, dry place to plant the following year.
  • For more information on saving seeds, check out CSU Extension Fact Sheet #7.602 from

Gardening Q&A

By: Lee Stewart
Colorado State University Extension Master Gardener in Larimer County

Q: When do I harvest potatoes for fall and winter use?

A:  Potato plants mature and die 70 to 100 days after planting. Harvest tubers 10 to 21 days after the plants die back. This step is important so potatoes “set their skin,” and also helps decrease bruising during harvest. Cure potatoes at 50-60 degrees F for two to three weeks. Store the potatoes in an area with 90% humidity at 38-45 degrees. To prevent rot, don’t allow condensation to form on the potato surface.

Q:  I never have red sweet peppers. How do I grow them so I can get a harvest?

A: Colorado has a short growing season and it may not be long enough to get bountiful quantities of red peppers. When peppers reach mature size, they usually turn red. Harvest peppers with a hand pruners to prevent plant damage. Frequent harvests encourage new fruit to form.

Q: The tops of my onions are laying on the ground. Some have tough stems with seed heads.  Is this normal?

A: Seed heads should be cut off when they first appear to allow better onion bulb development. Onion tops normally lay down in mid-summer. When 80% of the tops are brown, lift the onions out of the ground just enough to break the roots. Let cure in the garden for a few days, cut off the dried tops and harvest.

The authors have received training through Colorado State University Extension’s Master Gardener program and are Master Gardener volunteers for Larimer County.

Larimer County is a county-based outreach of Colorado State University Extension providing information you can trust to deal with current issues in agriculture, horticulture, nutrition and food safety, 4-H, small acreage, money management and parenting.  For more information about CSU Extension, Larimer County, telephone (970) 498-6000 or visit

Visit PlantTalk Colorado ™ for fast answers to your gardening questions! PlantTalk is a cooperation between Colorado State University Extension, GreenCo and Denver Botanic Gardens.

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