Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
March, 2008
Regional Report

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Fragrant by day and luminous by night, peacock orchids are a must-have.

Essential Tender Summer Bulbs

My garden is still buried underneath mounds of snow and this morning the temperature was in the single digits. But the calendar says it's spring, and it must have spread the word to my overwintered summer bulbs because the potted crocosmias that I moved into storage last fall have begun sending up new shoots. They reminded me to check on the other tender bulbs and tubers that have spent the winter indoors. New growth means it's time to bring them into the light and give them a drink to jump-start the growing season.

Many New England gardeners have experience keeping dahlias from year to year, but there are numerous lesser-known bulbs (I use the term loosely) that will win you over if you give them half a chance.

Crocosmias (also called montbretia), peacock orchids, and gladiolus are some of my favorite tender bulbs (technically corms), and not only do I love their flowers, their spiky foliage has nice form and is long lived. Another favorite, caladiums, are nothing but foliage but they need nothing else. By keeping all of these plants in large containers, I can get flowers sooner and feature them close-up on my deck and patio or by the front door. The only downside to starting these plants indoors is the space and tending they'll need. But to me, they are well worth the trouble.

Tried-and-True Glads
Last summer was the first time I've grown glads in pots, and from now on I'll always reserve some of the corms for container growing. Their beautiful, tall foliage adds to their value, especially when combined with bushier plants like dahlias or airy flowers like Euphorbia 'Diamond Frost'. Give them a well-draining -- even sandy -- soil mix and plant the corms 8 inches deep. (Bulbs and corms with a tall sheaf of sword-like leaves are best planted extra deep to give them added support in strong winds.) The shorter butterfly gladiolus are another good choice for containers; they only grow about 2 to 3 feet high. There are too many colors and varieties to mention.

Glads benefit from a dose of fertilizer high in phosphorous at planting time, at the first sign of flower spikes, and again when in full flower. You can prolong the display by planting glads every two weeks. After flowering, leave the foliage to replenish the corms for next year's flowers. They are only hardy to zone 6 or 7, so in most of New England this means moving the pots or individual corms indoors to a dark, 35- to 45-degree place. Keep them dry during storage.

Graceful Peacock Orchids
If you've grown glads, you already know how to treat peacock orchids and crocosmias. Peacock orchids (Acidanthera bicolor or Gladiolus callianthus) are not orchids, but apparently someone thought they were just as lovely. They are relatives of glads in the iris family, and they are as easy as glads to grow, although they require a longer growing season and start blooming later in the summer if planted in the ground. Growing about 3 feet tall, they have sword-shaped leaves and tall, arching flower stems topped with dainty white flowers with a maroon blotch in the throat. What's more, they are lightly fragrant.

Plant the small corms in groups of a dozen or more. While I haven't tried successive plantings yet, I have found that those I planted in pots bloomed earlier than those in the ground, even when planted at the same time. So that's one way to keep the blooms coming longer. Store them over the winter alongside your glads.

Hot Croscosmias
The tube-shaped flowers of croscosmias in warm reds, oranges, and yellows arise from the ends of 2- to 4-foot stems amidst sword-shaped leaves. They typically bloom later in summer, but you can get earlier blooms in containers. These plants will rot if the soil stays too wet, so use a well-draining soil mix and drill drainage holes if your pot lacks them. 'Lucifer', one of the most common varieties, wears scarlet (what else?) blooms; 'Emily McKenzie' has yellowish orange flowers; 'Lady Hamilton' is apricot with dark red streaks; 'Fire King' has bi-colored blooms of orange and red.

Their hardiness rating is reliably zone 6, but with good snow cover or winter protection they can tolerate zone 5. If grown in pots, they are best stored indoors along with your gladiolus.

Wildly Colorful Caladiums
Speaking of winning foliage, the caladiums are hard to beat. I'm pulling pots out of storage of a particularly flamboyant green, pink, and white number (name to be determined). These tropical plants will need to stay indoors at about 70 degrees until the weather has warmed up outside, about tomato-planting time. Give them two months to get to planting-out size if you start them from tubers. Plant them in a potting mix that includes compost or peat moss and keep the soil moist. They need shelter from direct sun but they need good light for the best leaf coloration. Caladiums also need warmth during winter storage, so bring them -- pot and all -- into a 70- to 75-degree location and leave them alone until spring.

One trick for bushier caladiums: pinch or scrape away the largest central bud or growing point on each tuber before you plant. This promotes the growth of the smaller surrounding buds and results in more shoots and leaves, although individual leaves will be smaller.

Making More Dahlias
Did you know that one dahlia tuber can produce several plants? Instead of planting the tubers in the ground, start them indoors in shallow containers about two months before outdoor planting time. Set tubers on light potting mix, barely covered, and begin watering. Keep the containers in a bright, warm spot, and in about three weeks the tubers should send up sprouts. When sprouts are 3 inches high, cut them with a sharp knife just above the tuber. Plant these cuttings in small containers of potting mix, up to the bottoms of the lowest leaves. Keep soil moist and when cuttings have rooted, transplant them into individual pots. Move them into larger containers for the deck, and plant the tubers in the ground.

Garden centers and nurseries are stocked with all of these bulbs now so happy shopping and planting!

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