Alan N. of Santa Rosa asks two questions: When it’s time to cut down my sunflower plants, can I chop up the whole plant and dig them back into the soil to add organic matter, or do I need to toss them? Second, I’ve seen some beautiful colored sunflowers, other than the typical yellows. Where can I purchase those unusual varieties?

It would be great if you could incorporate the flower heads, stalks and leaves, back into the soil to add organic matter when the plants are done and the gardening season is over. Most gardeners tend to plant pretty much the same kind of plant in the same place every gardening season. People like certain plants in certain spots because they like that plant — its color, height and other characteristics. But sometimes planting the same plant in the same spot every year causes plant pathogens to build up in that particular area in the garden, which can then cause the host plant to become infected. If the plants are diseased and you didn’t know/see it, you’ve then incorporated the diseased plant material back into the soil. That’s not good. Look carefully at each plant to make sure it is free of disease. Don’t incorporate the diseased sunflower plants to the soil where you plan to grow sunflowers next year. If a plant is diseased, dispose of it.

As for where to get unusual and beautifully colored sunflowers? One place to look is SunflowerSelections.com, which develops these new selections. For more than 40 years, sunflower geneticist Dr. Tom Heaton has been developing ornamental sunflowers for the company, which has an incredible array of varieties it sells directly to the home gardener.

Every sunflower is the result of at least seven years of careful research and plant breeding that Heaton undertakes every season. Thousands of plants are grown each year in their breeding plots. Every single plant is followed from germination through flowering with data meticulously recorded for important traits that determine the type and quality of flower that the customers desire. The astounding range of colors and petal forms from sunflower is owed to their passion to create new flowers. When they are convinced that they have created yet another “new” sunflower that growers and gardeners will appreciate, pure source seeds are multiplied by their staff in strict isolation from other sunflowers before being offered for sale.

The company’s latest develop is the first white sunflower. Procut White Nite and Procut White Lite will be released in November for next summer’s growing season. Burpee’s is featuring a white sunflower called ‘Coconut Ice’ and Baker Creek has an heirloom Italian White sunflower.

Dana Lozano and Gwen Kilchherr are garden consultants. Send your gardening questions to The Garden Doctors, at pdgardendoctor@gmail.com. The Garden Doctors can answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.

WHAT’S LEGAL POT GROWING AND WHAT’S NOT

Here’s a summary. For full legal information for Sonoma County, visit sonomacounty.ca.gov/Cannabis/Personal-Use-and-Cultivation/

Who Can Grow?

Medical: Any patient or caregiver with a doctor’s recommendation for medical cannabis. The cannabis cannot be sold or distributed

Recreational: Any adult 21 or older. The cannabis cannot be sold

Size of plants: Up to 100 square feet of grow area per residence

Medical amount: There’s no limit on the number of plants for medical use

Recreational amount: No more than 6 plants

Where: Cultivation must take place at the person’s full-time residence

Outdoor: Plants cannot be located in the front or side yard setback areas and cannot be visible from public streets or walkways. Outdoor growing is not allowed in multi-family units or in the medium or high-density residential zones (R2 and R3).

Indoor: Indoor grows must be in an accessory structure, like a greenhouse or garage. Growing inside a residential structure is not allowed, unless there is no feasible alternative.

WHERE DO I GET PLANTS OR SEEDS?

You can get seeds from suppliers on the internet. The Gage Green Group (gagegreen.org) is a reputable company selling organically grown seeds for medicinal or recreational grows. Close to home, The Cali Connection (thecaliconnection.com) is a website to look into. Farther afield, in Amsterdam in fact, is a fine company called Sensi Seeds (senjsiseeds.com) that sells medicinal, recreational and feminized seeds.

If you want to do more research, here are other seed suppliers to Google: Brothers Grimm Seeds, Swamp Boys Seeds, BC Bud Depot, MTG Seeds, DNA Genetics, TGA Genetics, Green House Seeds, Archive Seed Bank, Aficionado Seeds, Amsterdam Genetics and The British Seed Company.

You can also stop by the Emerald Cup at the Sonoma County Fairgrounds in December. An Early Bird Weekend Pass is on sale now for $120 plus $12.74 fee, no babies in arms and no strollers. You probably don’t want to take the kids to this event anyway. For tickets, visit theemeraldcup.com/tickets/

For starter plants, talk to a growe.r

Identifying gender of cannabis plants

If you let the male plants spread pollen among the females, you’ll ruin your crop, unless your aim is to grow and harvest seeds. If pollinated, the females will put their energy into ripening seeds, not producing big kolas of flowers.

Male and female marijuana plants are identical for the first six weeks of life. After June 20, they will start to differentiate by gender. If you’re serious about growing quality plants, you must remove all male plants and get them off the property or bury them as soon as you can tell their gender.

Use a magnifying glass to look at the joints on the stalk where the branches meet the main stalk. At first both males and females will have small clusters of ball-like bulbs there, but soon small, hairy, translucent filaments will emerge from the female bulbs. When many of the female bulbs show these filaments, it’s time to remove the male plants, which will still not have filaments but will soon shower the patch with pollen. Pull them out and get rid of them asap.

For more information and pictures, visit wikihow.com/Identify-Female-and-Male-Marijuana-Plants