Extra early season upends gardening calendars

Brunnera macrophylla ‘Jack Frost’ has enchanting silvery leaves with green venation and a thin green margin — Photo courtesy of Perennial Plant Association website

The Perennial Plant Association’s 2012 Perennial Plant of the Year is the lovely spring-blooming Brunnera macrophylla, ‘Jack Frost.’ To the many who already know and love brunnera, with its mid- to late-spring sky-blue flowers similar to forget-me-nots, meet ‘Jack Frost,’ with its silver-dusted, heart-shaped leaves making eye-catching mounds. This plant would rate a spot in the spring or shade garden based on foliage appeal alone. The suggested uses for ‘Jack Frost’ include containers, front of the shade border, or partnering hostas, ferns, epimediums, and dicentra. During the hottest part of summer, brunnera may die down, but it will re-appear with the return of cooler weather.

Indoor gardening

Chitting dahlias may be started now. To chit, bring dahlia tubers out of their storage conditions, into room temperature and light. Some gardeners lay them in pie pans, or similar container, and spritz them lightly with water from a sprayer bottle. Others place them in boxes or containers of some sort and cover them with compost. Sprouting will take place shortly. These sprouts may be cleanly cut from the tubers, treated with rooting hormone, and grown on exactly as any other cutting. Or sprouted tubers may be separated and potted up individually in dampened potting medium and grown on.

To my recent piece in the Home & Garden supplement on seed starting, I would like to add some comments. Shepherd Ogden, one of the influential figures in the grow-your-own movement and a vegetable authority, recommends mixing one tablespoon fish emulsion and one tablespoon liquid seaweed per one gallon of water, then using it diluted one-to-four on seedlings. This dilute solution can be used every time seedlings are watered, eliminating the need to keep track of weekly feeding schedules.

The other point, about which I am not fully clear but which should be mentioned, is the tendency of bolting in certain seedlings if they are set out too soon and experience temperatures that are too low. Two years back I started Swiss chard seedlings and got them into the garden nice and early. To my disappointment, the plants started to bolt after a short while, leaving me in a state of consternation. Swiss chard is a biennial, it is cold hardy, and this had never happened before….

The explanation seems to be that these seedlings— spinach and leeks are others — are biennial and need to be kept from experiencing temperature extremes: for instance warmth, then too much cold, when young. This can trigger the plant’s physiological calendar into thinking it has gone through a winter cycle and is now supposed to bloom and set seed.

A rule of thumb for seed-starting is to maximize light and minimize temperature: deliver as much light to the seedlings as possible, at the coolest temperature possible, to promote healthy, stocky plants.

In the garden

Time to cut back epimediums, lavender, buddleia, and to prune hydrangea, potentilla, caryopteris, and Montauk daisies. While there is still the risk of an unexpected weather event, the season is moving forward, early though it may be, and these plants are in growth.

With lavender and epimedium, shearing is the style of cutting back to perform. Most lavenders will have bushy growth around their bases, with more battered-looking spikes sticking up. Shorten these, going back to viable buds or sprouts. While some epimediums will have come through this mild winter with very healthy looking foliage, others will look tattered. The dainty flowering stems are difficult to discern among the leaves. Cut it all back, before the flowering stems emerge; the leaves will follow.

Prune hydrangeas by thinning aged canes and trimming off old flowering heads back to the first or second pair of strong buds. Cut potentillas, hypericums, caryopteris, and Montauk daisies back by about two thirds.

Soil temperatures in various parts of my vegetable garden are hovering around 45 to 48°F. A way to warm soil is to hoe up raised beds now, which warm faster than the surrounding ground. Or laying black plastic or tarps on garden soil (well-secured) is a technique that is used not only to raise soil temperatures, but also to kill weeds, similar to the stale seedbed.

A seedbed is prepared and cultivated, bringing existing weed seeds to the surface. When the weeds germinate they may be cultivated out or cooked with black plastic mulch. The residue is tilled in for its nutrient content.

Cover crops have started into growth. They may be mowed with the blade set high if growth is more than can be tilled in. The residue is similarly incorporated as a soil improver, as above, after which the soil sits for about three weeks, to allow for decomposition.

Winter moth info

Robert D. Childs, UMass Extension Entomologist, on the winter moth: “Winter moth caterpillar needs to have its host plant bud-break phenology in close synchrony with egg-hatch…. One possibility is that the eggs will hatch extremely early this year and the host plants will lag far enough behind with their bud swelling to be non-useful to the caterpillars leading to their starvation. Deciduous plants that are currently dormant will experience a slight effect from the warm winter but are not nearly as affected by these temperatures as are the insects and, therefore, may not be ‘ready’ for the winter moth should it appear much earlier than the norm. Success for winter moth is strongly tied to being in close synchrony with the host plant bud swelling and opening.”

For more winter moth information, go to: http://extension.umass.edu/landscape/fact-sheets/winter-moth-overview.

MV Agricultural Society hosts the annual spring potluck supper and social Saturday, March 31, 6 pm, at Agricultural Hall, 35 Panhandle Rd, West Tisbury. Susan Klein and Alan Brigish will present “History of 150 Years of Local Agriculture.”