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Lowenfels: As snow melts, postpone pruning

Jeff Lowenfels

Lots of questions this time of year. The snow is melting fast enough so that most now believe this really is spring. Having noticed, they ask things like: "Is this a good time to trim up trees and shrubs?"

Actually, this is a really bad time to trim most stuff outside, in my humble opinion. A little earlier when the temperatures reliably stayed below freezing would have been fine, but it is too late now that temperatures are hitting the mid 30s during the daytime.

Prune now and not only are you going to miss the greenery so badly needed (and in the case of lilacs, their flowers this year), but you risk dripping sap from the cut. What this means is that during the days when temperatures are above 32, water is flowing from the roots up into the branches (through the xylem tubes). This time of year, sugars stored in the roots as starch are transported up with water.

Xylem tissue cannot repair itself and just drip sap. Later in the season these sugars run in the phloem which can actually shut itself off. Cut a branch or limb this time of year this xylem sap flows out. It can be messy, especially when you are dealing with a birch. (Birch syrup, anyone?) Hold off until after things have leafed out and the phloem takes over carrying the sugars.

Next, what about those emerging bulbs that were caught by the snows? Are they going to make it?

Fortunately, there is no cause to worry about bulbs that were up. These all have antifreeze systems that protect them from frosts. If they had been in flower, however, things would be different. And, depending on break-up, it may be different for the bulbs that have not appeared yet. A long break-up tends to result in lots of rotted bulbs.

One reader asked if it was possible to grow a bigger dinner plate dahlia or tuberous begonia flower by not pinching back these plants back this time of year. Is this true?

In my experience it is partially true. You can grow Alaska Fair-size begonia and dahlia flowers by not pinching back the plants. However, you do need to pinch back all but one or two of the flower buds so that you limit the number of blooms into which all that plant can put its energy. Its a risky venture if those one or two flowers get damaged.

Several folks have asked about those pesky little flies. It must be going around. The question is how to get rid of the fungus gnats that seem to love their compost starter mix.

Fungus gnats are annoying, but they won't hurt the crop. Still, a hit of AzaMax or other neem oil-based insecticide will help. So will checking your watering habits. If you let the top of the soil dry out in between waterings, they should abate. Air circulation will also reduce numbers, but don't dry out the plants.

My favorite question this week -- and I think it was to settle a debate between spouses -- was whether it matters if the temperature used to water plants is warm or cold. This was a divided family.

From a scientific point of view, warm water is best for your soil. For one thing, nitrogen-fixing bacteria (and there are plenty in your potting mix) and the kinds of other microbes that help plants grow and improve soil structure do best around 70 to 75 degrees. Alaskan tap water can be as low as 38, especially if it is from a well.

Not to take sides in the fight, but getting warmer water to house plants is easy. You can turn the tap for warmer water or let cold water sit at room temperature. It's a bit more difficult to get it to the right temperate water to plants outdoors. It's worth contemplating, however.

Finally, how deep can you transplant a tomato?

This last question is a timely one. Now is the time to start thinking about transplanting tomatoes, either plants purchased or started at home. Tomato stems and leaf sites (sans leaves) will develop roots if buried. You can bury plants as deep as you want provided one set of true leaves remains above ground. This first transplant is a good one to "bury deep" so your tomato plants will have a good foundation of roots for the season.

 

Join Jeff Lowenfels at "The Garden Party," 10 a.m.-noon on Saturdays on KBYR AM 700.

Garden calendar

START: DAHLIAS, SCHIZANTHUS, NIGELLA, PHLOX, NEMESIA, MARIGOLDS, NASTURTIUMS.

NURSERIES: VISIT AND BUY

PEONIES IN ALASKA: JULIE RILEY FROM COOPERATIVE EXTENSION WILL TALK ABOUT GROWING PEONIES IN ALASKA AT 10 A.M. ON APRIL 20 AT ALASKA MILL AN FEED. THE CLASS IS FREE, BUT PLEASE CALL TO REGISTER, 276-6016.

UNIQUE PERENNIALS IN ALASKA: LOCAL ARTIST AND AWARD-WINNING GARDENER AYSE GILBERT WILL PRESENT INTERESTING AND UNUSUAL PLANTS TIPS ON TENDING A HEALTHY, NATURAL GARDEN AT 10 A.M. ON APRIL 27 AT ALASKA MILL AND FEED. THE CLASS IS FREE, BUT PLEASE CALL TO REGISTER, 276-6016.

 



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