Poppies next spring

I saw beautiful poppies in gardens this spring and summer and would like to grow some of my own. When and how do you plant them?

There are several types of poppies; some are perennials, some are cool-season annuals. A few of them can be grown from seed sown in the fall, so start planning now to have a garden of poppies next year. Here’s a short list of the possibilities, according to the editors of the Southern Living Garden Book:

Iceland poppy (Papaver nudicaule) is a short-lived perennial with cup-shaped blooms of yellow, orange, salmon, pink, white or cream. Sow seeds or set out transplants in the fall.

Oriental poppy (P. orientale) has large, crinkled blooms in scarlet, orange, pink, salmon or white that grow from bushy clumps of foliage. The blooms may be black at the base. Plant dormant roots in the fall.

Shirley poppy, or Flanders Field poppy (P. rhoeas) is an annual poppy with single or double flowers in white, pink, salmon, red, scarlet, lilac or blue. Sow in the fall by mixing seeds with an equal amount of sand and broadcast it where you want them to grow. Note: The Southern Living Garden Book says this is a “notorious self-sower,” which is usually a gentle way to say it could take over your garden whether you want it to or not.

Alpine poppy (P. alpinum) is a perennial that grows better in fast-draining, gritty soil. It has smaller flowers (1 ½ to 2 inches in white, yellow, orange or salmon. It, too, self-sows freely. Sow seeds in fall or early spring.

To plant poppy seeds, prepare the soil in a bed in full sun and simply scatter the seeds on top, or barely cover the seeds. Water the ground carefully, and kept the area moist throughout the fall.

Garden events in Middle Tennessee

Sept. 5:WarnerParkNatureCenter hosts Hummingbird Happy Hour, 4 – 6 p.m. at the WarnerParkNatureCenter. Bird banding demonstrations and other kid-friendly activities are on the agenda. Free admission, but registration is required; call 352-6299. While you’re there, visit the NatureCenter’s vegetable, herb and flower garden. Info: http://www.nashville.gov/parks/nature/wpnc.

Sept. 15: Urban Chicken Appreciation Day at Shelby Bottoms Nature Center, 10 – 11 a.m., celebrates feathered backyard friends. Learn how to get started in backyard chicken keeping in a session led by Bonnie Bowles. Call (862-8539) or email (shelbybottomsnature@nashville.gov) to register.

Sept. 22 & 23: Many rare and unusual houseplants will be available at the Tennessee Gesneriad Society’s annual Flower Show and plant sale, which will be held at Cheekwood’s Botanic Hall. The event is open to the public 9:30 a.m. – 4:30 p.m. Saturday, and 11 a.m. – 4:30 p.m. Sunday. To learn more contact Julie Mavity-Hudson at Julie.mavity@gmail.com.

Sept. 29: Herb Society of Nashville’s Herb Day at Cheekwood’s Botanic Hall: “Cooking & Gardening with Native Plants.” 9 a.m. – 4 p.m.; admission is $40 plus Cheekwood gate fee. To register: www.herbsocietynashville.org.

Prevent powdery mildew

QUESTION: How do I keep my beautiful zinnias from getting powdery mildew? It may be too late for this year, but what should I do different next year?

Powdery mildew is a fungus that thrives when nights are moderately cool and foliage stays damp. It travels by airborne spores, and appears as gray or white splotches on leaves, stems and flowers of susceptible plants, such as zinnias. A mild case is merely unattractive; a severe case of powdery mildew can cause distorted shoots and leaves, misshapen flowers or can prevent flowering altogether.

The best defense is to give zinnias room to grow without crowding, which allows air to circulate better around the plants, and water only in the morning, so the foliage has time to dry before nightfall. Cut back on the use of high-nitrogen fertilizer, which produces succulent new growth that is a major powdery mildew magnet. Grow them in full sun; hot temperatures (above 90 degrees) inhibit the growth of mildew.

There are fungicides available that should be applied as soon as you begin to spot the mildew (so yes, probably too late for this year), but I always suggest trying the good-cultural-practices method first. The University of Tennessee Extension has a short list in a publication about powdery mildew here. If you decide to go that route, be sure to read and follow directions on the product label.

Zinnias are not the only things plagued by powdery mildew. Lilacs, roses, crepe myrtles and other woody ornamentals, and many herbaceous ornamentals and bedding plants are also targets when weather conditions favor the fungus.

Coming up

July 17: Middle Tennessee Orchid Society meets at 7 p.m at Cheekwood. On the agenda: an orchid auction and discussion on Cattleya Orchids. To learn more, visit www.tnorchid.com.

July 17: Perennial Plant Society meets at Cheekwood in Botanic Hall. Refreshments and plant swap at 6:30; meeting and program at 7. Guest is Kelly Norris, horticulturist, plant breeder and manager of Rainbow Iris Farm in Bedford, Iowa will present “The Modern Plant Explorer.” The meeting is open to the public.

July 26: Farmer Jason performs at Family Night Out at Cheekwood, 6:30 p.m. The event is free with regular Cheekwood admission. www.cheekwood.org.

Garden seeds: How old is too old?

QUESTION: How long do seeds last? If a seed packet says “purchase by 12/11,” would the seeds still be good for this year?  I’m looking at sunflowers, green beans, and other summer vegetables.

Packed for 2011. Still good? Probably, if they’ve been kept dry and cool.

It’s probably a common experience among gardeners to find packets of last year’s seeds – or seeds from two or more years ago (opened or unopened) stashed in a forgotten corner. They look too good to throw away, but is it worth wasting time and space in the garden to plant them if they may not germinate?

The good news is that many seeds last beyond the “sell-by” or “packaged for” date that’s printed on the packet, especially if they’ve been kept in favorable conditions – dry and reasonably cool. Seeds of parsnips, onions and leeks are among those that will only be good for a year, but seeds of most of the common garden vegetables can last two, three, or some, even five years. Here’s a short list from vegetable researchers atOregonStateUniversity:

Two years: sweet corn, lettuce, parsley, peppers, chard.

Three years: Bush and pole beans, carrots, cucumbers, melons, peas, squashes, tomatoes.

Four years: radishes, turnips.

Seeds of annual flowers are generally good for 1 – 3 years, the researchers say; seeds of perennials can last 2 – 4 years.

You can test the viability of a packet of seeds by placing a few in a moist paper towel in a warm room for a few days to see if they germinate. Seed Savers Exchange provides detailed instructions here.

If you have seeds left at the end of the season, the best way to store them is in a sealed jar with something to absorb moisture (rice or powdered milk are two suggestions). Store the jar in the refrigerator or a cool area in the house, such as a basement.

Garden events

The Mid-South Chapter of the Lupus Foundation’s Down the Garden Path garden tour and plant sale May 19 and 20. Visit nine gardens in Belle Meade, Green Hills and Franklin. 10 a.m. – 5 p.m.Saturday, noon– 6 p.m.Sunday. Tickets are $20 prior to the event, $25 on tour days, and proceeds benefit the Lupus Foundation of America, Mid-South chapter. www.lupusmidsouth.org.

Coming in June

Seeds of Hope self-guided garden tour, June 2. Six gardens in Belle Meade, Green Hills and Oak Hill, 9 a.m. – 3 p.m. Tickets $25; proceeds benefit Monroe Harding programs for children. www.monroeharding.org.

The Nashville African Violet Club meets June 3 at 1:45 at the Green Hill Women’s Center, 10905 Lebanon Road in Mt. Juliet. E-mail Julie.mavity@gmail.com to learn more.

Gardens in Rugby, Tenn. will be open to visitors on June 9.

Plan a road trip on June 9 to Rugby, Tenn., for an all-day event at Historic Rugby Cumberland Plateau Gardens. The day begins at 9 a.m. (Eastern Daylight Time) with “Rugby Landscape Gardening From 1880 to 2012” by Rick Murphy, followed by  “Garden Design Sun to Shade” a workshop by Bob Washburn of Wolf River Valley Growers. Lunch, garden tours and a British Cream Tea round out the schedule. The cost is $40, and advance reservations are required. Proceeds benefit Historic Rugby. Information, 888-214-3400.

The Tennessee Gesneriad Society meets June 10 in Cheekwood’s Botanic Hall at2 p.m. Program is a Mini Show. Contact Julie at 615-364-8459 to learn more.

Perennial Plant Society monthly meeting at Cheekwood, June 19,7 p.m. in Botanic Hall. June meeting is potluck dinner and photos of members’ gardens.

Sweet surprise: sweet potato vines

QUESTION: The ornamental sweet potato vines I grew in large pots last summer produced potatoes – to my surprise! Can they be replanted to produce vines next year?

Sweet potato vine (Ipomoea batatas) ‘Blackie’

Yes! The sweet potatoes that are grown for their ornamental vines don’t have much taste, but U.T. Extension agent David Cook says you can save the tubers to produce the same foliage next year. Here’s how to do it:

If the potatoes haven’t already frozen (and by now, you may find that they have, unfortunately), dig them up and store them packed in straw in a dry, cool place. When the weather begins to get warm again, the tubers may begin to sprout. Cut them into sections just as you would cut a seed potato, with at last one “eye” per section. Allow them to dry for a few days, and plant them in the ground after the frost date has passed (mid-April here in Middle Tennessee).

Ornamental sweet potato vines come in a variety of fancy-leafed “flavors.” ‘Blackie’ is an easy-to-find favorite, with purplish-black, deeply lobed leaves. ‘Ace of spades’ has heart-shaped leaves. ‘Tri-color’ is variegated with green, white and pink foliage, and the variety called ‘Marguerite’ has golden-green leaves.

The vines grow fast, and are a striking addition as a “spiller” in a container, draping elegantly over the sides. I learned last summer that rabbits find the leaves tasty. If your garden has a resident rabbit (as mine does), you’ll find the vines will start to disappear, so be warned.