Dear Master Gardener: My orchid won’t rebloom. How long will an orchid live as a houseplant? Do they rebloom?

Answer: Assuming you have a Phalaenopsis, which is the most common orchid grown as a houseplant, they will typically bloom for two to three months, then go into a rest period. Unfortunately, many people throw them out when they’re done blooming, but with the right care, you should be able to keep your orchid for decades. A Phalaenopsis orchid can bloom anywhere from one to three times per year. The most common reason for an orchid not re-flowering is inadequate light. They like bright light but not direct sunlight, so if you have a plant that is not re-flowering, move it to a brighter window. Phalaenopsis orchids benefit from light fertilization. Over-fertilizing them will result in lush foliage at the expense of flowers. As a general rule, fertilize actively growing and flowering plants every third or fourth watering with an orchid fertilizer, following the directions on the label. Phalaenopsis orchids tend to form new flowering branches along their old flower spikes. To promote re-flowering, prune yellowed or brown spikes back to about one-half inch above the second node or swelling along the spike above the foliage. Old, dried-up, brown flower spikes can be cut off at the base of the plant.

Related: Ask the Master Gardener: Getting your garden ready for winter

Dear Master Gardener: Tell me about the Saran Wrap method of overwintering dahlias.

Answer: Several years ago, commercial dahlia growers in the Pacific Northwest started wrapping their cleaned, separated and cured dahlia tubers in plastic wrap. Their results, which have finally been tested by Washington State University, have been impressive. I adopted the method and have had much better success at not losing tubers to drying out or rotting. And the biggest bonus has been that they get labeled and stay labeled!

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After a hard frost, dig the tubers as usual. Some varieties make a lot of tubers, some just make a few. Hose off as much dirt as possible and then prepare to do surgery. Study pictures of tubers so you learn what the eye looks like. The size of a tuber has nothing to do with whether you will get a new plant next spring — it’s all about having at least one viable eye. A potato-sized tuber with no eye will never grow a plant, but I’ve gotten new plants from pencil-lead sized tubers with good eyes. The eyes will only form on or near where the stem of the plant you dug up turns into a tuber. Using very sharp nippers or pruners or even a box cutter, snip off all the hairy roots and any damaged tubers. Separate the remaining tubers, making sure you have an eye or at least part of the stem on each one.

Coating dahlia tubers in vermiculite or sand, along with a teaspoon or two of powdered sulfur, and storing them in a piece of plastic wrap will help keep them over winter. 
Contributed / Jackie Burkey
Coating dahlia tubers in vermiculite or sand, along with a teaspoon or two of powdered sulfur, and storing them in a piece of plastic wrap will help keep them over winter. Contributed / Jackie Burkey

Let the tubers dry for a day or two — lay them out on newspaper or cardboard in a warm, dry place with good airflow. The garage is OK, but don’t let them be directly on the concrete — it sucks all the moisture out of them. They have to stay above freezing. Don’t let them sit too long — they will dry out. Write the variety name (or some code) right on the tubers with a sharpie marker — it may prevent confusion later on.

Put a couple cups of fine vermiculite or sand in a gallon Ziplock bag, along with a teaspoon or two of powdered sulfur, which is an excellent fungicide and will help prevent rotting. Don’t use too much sulfur — you don’t want to create sulfuric acid! Add a handful of tubers and do a very gentle “shake and bake” to coat all the surfaces. Take a piece of plastic wrap about 20 inches long. Place the first tuber near one end, roll it so the entire tuber is covered, then place the next tuber, making sure they don’t make contact. Roll and repeat. When you have about 6 inches of plastic left, fold in the sides then tape down the remaining flap to make a neat little packet. Write the species name on the tape and place all the little packets into a shoebox or cardboard box. Store the box in a cool, dark place — 40-50 degrees is perfect. If the tubers freeze, they die. If they are too warm, they sprout early and grow long, spindly sprouts.

Dahlia tubers wrapped in plastic wrap, labeled and ready for winter. 
Contributed / Jackie Burkey
Dahlia tubers wrapped in plastic wrap, labeled and ready for winter. Contributed / Jackie Burkey

In the spring, plant the tubers early in pots in April if you want a head start or wait until the ground has warmed around mid-May. The eyes should be obvious, and probably sprouting. Don’t bother to plant any tubers without eyes — you’ll never get a plant, no matter how perfect the tuber looks.

Related: Ask the Master Gardener: A few tips for overwintering geraniums

Dear Master Gardener: Help! Woodpeckers are ruining our cedar siding.

Answer: Wood siding, especially soft wood like cedar, attracts woodpeckers who leave behind holes ranging in size from a quarter inch to 1 inch or more. One day a few years ago I noticed drywall dust on my nightstand. When I looked up there was a hole in the wall. A pileated woodpecker (which will give you an idea of how big the hole was) had pecked through the cedar siding, sheeting, insulation, and drywall, causing significant damage. Woodpeckers peck for three reasons: communicating, feeding, or roosting. They often focus on the area just below the eaves. The “drumming” you hear is the woodpecker searching the house for hollow spaces. If it’s looking for food it will usually leave several small (less than ½ inch) feeding holes scattered over an area or formed into rows. One or two larger holes (an inch or more) are typically a sign of roosting or nesting behavior. It is critical to take action as soon as a woodpecker starts making holes in your siding, and before it has time to make it a part of its routine.

Here are some ideas from the University of Minnesota and DNR:

  • Hang bird netting from the outside of the eaves to the side of the house about 18 inches below the roof line. Bird netting can also be hung to cover the entire side of a house. Hang it at least 4 inches out from the house staring at the roof line. You will need to close off the ends so that birds cannot get underneath.

  • In hard hit areas attach 1-inch by 1-inch boards to the house and then place metal screening over the boards to prevent the woodpecker from reaching the house.

  • You can purchase scare-eye balloons, which are designed to look like a large predatory bird eye. Place the balloons in front of the affected wall or area and move or remove them after about a week so the bird doesn’t get used to them.

  • Fake owls with mechanical heads that rotate and screech have been effective as a deterrent. Place them 10-15 feet high in a visible spot, such as the edge of the roof or upper floor deck railing.

  • Bird scare tape, also called flash tape, is a thin shiny ribbon of Mylar. It’s silver on one side and colored on the other. The tape flashes in the sun and rattles in the breeze, frightening the birds. Tack several long streamers above the affected surface about a foot apart, making sure they are able to move in the breeze.

  • Attach pie tins or unusable CDs or DVDs to a string and hang them in front of the affected area. Tins should be placed so that they spin freely in the wind.

It’s important to keep in mind that woodpeckers are a protected species and it is illegal to kill or trap one without a permit.

Related: Ask the Master Gardener: Hyacinths can fill your home with fragrance

You may get your garden questions answered by calling the new Master Gardener Help Line at 218-824-1068 and leaving a message. A master gardener will return your call. Or, emailing me at umnmastergardener@gmail.com and I will answer you in the column if space allows.
University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. Information given in this column is based on university research.