Dahlias raised from tubers larger than seed-grown

Q. I was surprised while looking through seed catalogs that dahlias can be grown from seed. I always raise a few every year from tubers. Any tricks to raising these plants from seed? – M.D., Rockport

A. Many of the dwarf hybrid dahlias are grown from seed. Some older varieties may also bloom in the first year when produced from seed. In general, seed-grown varieties are smaller in stature, reaching only 1 to 2 feet at maturity. The larger “dinner plate” dahlias that reach 4 to 6 feet at maturity are propagated vegetatively from tubers.

While the larger dahlias often are grown as specimen plants, seed-grown dahlias typically are massed together in a carpet bedding arrangement in the landscape. ‘Figaro Mixture’ is one often used. It reaches only 12 inches and produces droves of bright flowers that make it a cheery addition to the garden. This cultivar and dahlias in general prefer sun to partial shade and well-drained, rich, moist soil.

As for raising the plants from seed, germination takes place around 70 degrees F. Sow seeds four to six weeks before the last expected frost in spring. Broadcast them over a fine medium and dust with a shallow application of medium over the seed. Keep the medium and seeds moist but not soaking wet.

When the seedlings produce their first set of true leaves, transplant them into their own pot or cell pack and fertilize at every watering with a half-strength application of 20-20-20 fertilizer.

Q. This winter has pointed out that perennials in our area need to be particularly hardy to survive over the years. Can you provide a list of some plants that are hardy to the negative numbers we’ve seen on the thermometer this year? In other words, which ones do you think will actually survive the deep cold we’ve had? – L.S., Bangor

A. While it’s impossible to predict which plants will pull through the winter gloriously, I can list for you some plants that (technically, at least) are hardy to minus 30 degrees F.

Among the hardiest garden flowers are ajuga, balloon flower, basket-of-gold alyssum, danesblood, red swallowwort, lupine, baby’s breath, Maltese cross, wormwood, yarrow, helenium, golden marguerite, great lobelia, cardinal flower, peony, bachelor’s buttons, purple coneflower, gas plant, obedient plant, evening primrose, liatris, Greek valerian, alpine aster, bleeding heart, Oriental poppy, lungwort, meadowsweet, goatsbeard, Joe Pye weed, monkshood and phlox.

As you see, one could grow quite a garden with these hardy species alone.

Q. Every year I see luscious photos of watermelons in seed catalogs, but every year I chicken out and don’t grow them because I figure our summers are too cool and not long enough. I notice, though, that some of these modern melons don’t take so long to come to bear. Have you had any luck with these sweet treats? – P.M., Prospect

A. In fact, yes, we have. My daughters raise a few ‘Sugar Baby’ plants from seed every summer and have always gleaned at least a few melons. It’s no surprise that these melons prefer a lot of supplemental irrigation. In dry summers when we haven’t been diligent with the watering, the melons are few and somewhat hard and late to bear. In years when we’ve been on the ball, the vines have rewarded with many perfectly round 12-inch melons that were dripping with sugary sweetness.

Watermelons are easy to grow from seed – and I encourage you to give it a try! The vines are lush like many other members of the cucurbit family. The foliage is silvery and deeply lobed, making the plant a pretty addition to any garden, even in years when the produce may not be so ample.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, 512 North Ridge Road, Montville 04941, or e-mail dianagc@midcoast.com. Selected questions will be answered in future columns. Include name, address and telephone number.