Maine Home Garden News — March, 2010

seedlingsMarch Is the Month To . . .

By Hannah Todd, Horticulture Aide, University of Maine Cooperative Extension, Somerset & Piscataquis Counties,

  • Purchase seeds from a reliable source.
  • Start seedlings according to their temperature requirements (soil and air) and growing schedule.
  • Start plants such as head and leaf lettuce, celery, onions, pansy, and geraniums. By mid to late March, it is safe to start peppers, tomatoes, ageratum, and alyssum, to name just a few.
  • Take care while watering seedlings. If you have chlorinated water, allow water to sit in an open container for 24 hours before use.
  • Provide seedlings with adequate light (14 to 16 hours a day).
  • Wash pots with a 10 percent bleach to water solution.
  • Prune fruit trees and certain shrubs. Typically, shrubs that flower after June should be pruned in the late winter/early spring, but it is important to know what stage of bud development the shrub is in before you prune! Keep in mind the rudimentary three “D’s” when pruning: remove damaged, diseased, and dead branches.
  • Check fruit tree trunks for mice, voles and rabbit damage.
  • Prune raspberries and blueberries before the buds break.  See article on pruning in this issue.
  • Transplant cold-hardy vegetables (greens) to cold frames or hoop houses.
  • Plant greens and root crop seeds directly in cold frames or hoop houses.
  • Wait until your garden spot has dried before tilling. Tilling wet soils destroys soil structure and causes clumps of soil to form, which makes general gardening practices hard to perform (seeding, hoeing, etc.).
  • Attend your local Maine Maple Sunday event (always the 4th Sunday in March).
  • Clean your magnifying glass and get ready to look for spring pests. The lily leaf beetle will be showing up in April!
  • Start cleaning up perennial beds as the snow leaves by removing debris from last season.
  • Rake out mole hills on your lawn with a hard rake.
  • Consider starting a garden journal this year by keeping track of your garden related activities and items such as temperatures, tree bud break, bulb emergence, wildlife sightings, etc.

girl peeks into bucket that is collecting maple sapHow to Tap Sugar Maple Trees

By Kathy Hopkins, Extension Educator, University of Maine Cooperative Extension in Somerset County,

No one really knows who discovered how to make syrup and sugar from the sap of a maple tree. However, we know that maple syrup was an important commodity in the North American Indian economy. Maple syrup and sugar were used for barter by Indians living along the Great Lakes and the St. Lawrence River.

How Much Syrup Can I Get?

The yield of sap varies much with the method of tapping, the size of the tree, and seasonal differences. Sugar maple trees (Acer saccharum), also known as rock or hard maple, are usually the best producers. Red maples (Acer rubrum) also provide sweet sap. Sugar content can also vary by time of day. It may be high in the morning and lower in the afternoon.

What Happens in the Tree?

In the later summer and fall, maple trees stop growing and begin storing excess starches throughout the sapwood. This excess starch remains in storage as long as the wood remains colder than about 40 degrees F. Whenever wood temperatures reach around 40 degrees F, enzymes change the starches to sugars, largely sucrose. This sugar then passes into the tree sap.

As the temperature increases to about 45 degrees F, the enzymes stop functioning and sugar is no longer produced. In late March and April, depending on the weather, the sugar changes back to starch.

How to Do It

A tree should be at least 10 inches in diameter, measured at 4-1/2 feet above the ground, before tapping. Trees between 10 and 20 inches in diameter should have no more than one tap per tree. A second tap may be added to trees between 20 and 25 inches in diameter. Trees over 25 inches in diameter can sustain three taps. No tree should ever have more than three taps. The shape and size of the crown are also important. Trees with large crowns extending down towards the ground are usually the best sap producers.

Step 1: Drill the hole using a drill bit with a diameter of 7/16 inch, at a convenient height and two inches deep if you are using standard size spouts. If you are using small taps (5/16 inch), or the health spout (19/64 inch), use the corresponding drill bit size and drill the taphole only 1-1/2 inches deep. Look for unblemished bark. Do not bore closer than two feet directly over or under a former taphole or closer than six inches from the side of an old taphole. Drill the taphole with a slight upward angle so the sap flows out readily. Use a sharp drill bit to minimize rough wood in the taphole, which can reduce sap yield and cause sap quality problems.

Step 2: Tap in the spout so that it is tight and cannot be pulled out by hand. Don’t drive it in so hard that you split the tree. Tap on warm days when the temperature is above freezing to minimize the risk of splitting the tree.

Step 3: Hang your bucket or container on the hook of the spout if it is a purchased one; or, if you have made your own, fashion a length of wire to serve as a hanger. Be sure to cover the bucket to keep out rain, snow and foreign material.

Step 4: To boil sap, use a hobby-sized evaporator, an outdoor gas range or an outdoor fireplace. Prepare to boil the sap by making sure your selected fuel is ready in ample supply, and having a large pan or series of pans ready for the sap. (Do not plan to cook the syrup indoors on the stove, without a stove vent fan or a dehumidifier. Boiling sap creates a lot of steam.)

Step 5: Once the sap has started to run and you have collected enough to fill your pan for boiling, you are ready for the fire. Do not fill your pan to the top, as it will boil over.  A bit of butter or vegetable oil rubbed on the rim will often prevent boiling over.  As the sap boils down, keep adding more sap. Keep the sap at least 1-1/2 inches deep in the pan, or it may burn. You can pour cold sap right into boiling sap, or you can preheat it. It will take a lot of boiling to make syrup. Never leave boiling sap over a wood fire unattended. Sap can quickly boil away and burn the pan.

Step 6: Do not leave an accumulation of sap in the collection buckets, especially in warm weather. Sap is like milk: it will sour if left in the sun. Keep the sap in cold storage. Boil it as soon as you can.

Step 7: Sap becomes finished maple syrup when it reaches 66-67% sugar content and 7.1 degrees F above the temperature of boiling water. You can learn the boiling point of water, which varies depending on your elevation and the barometric pressure, by measuring the temperature of the raw sap when it begins a rolling boil. A syrup or candy thermometer is very useful. If you have a large operation, you might consider using a syrup hydrometer and testing cup to tell you when the syrup is done. Concentrations below 66% sugar content can sour over time. If the syrup is boiled above the 67% density of syrup, sugar crystals can form in the bottom of storage containers. Using a hydrometer is an accurate method of determining sugar concentration.

Step 8: When the syrup has reached the correct density and temperature, filter it to remove “sugar sand” before you hot-pack it in containers. Filter the syrup while it is still hot, through clean filter material such as wool or Orlon™, available from maple equipment dealers. If you don’t have filter material, you may put the syrup in a container and let it cool for 12 hours or more. The sediment will settle to the bottom and the clear syrup can be carefully poured off. This should be reheated to 180 degrees F (almost boiling) before it is poured into sterile containers for final storage.

Step 9: Syrup should be canned hot (180 degrees F). Pour the hot syrup into sterilized canning jars and seal. Fill them full so that very little air will be in the jar. Lay them sideways while cooling for a better seal.

Step 10: Store your syrup in a cool, dry place, with the jars turned on their sides to coat the air space at the top of the jar. After a container has been opened for use, it must be refrigerated. Should mold form on syrup that has been stored for several months, discard the syrup because of the possibility of contamination by microorganisms that may cause a food borne illness.

Step 11: After the season is over, clean your equipment with plenty of hot water and a solution of one part chlorine to 20 parts water. Use a brush or cloth to scrub any buildup or scum and triple-rinse with hot water. Never use soaps or detergents on any equipment, as these will leave a residue that will   contaminate the syrup with off flavors. Wash  filters with hot water only, as residues cannot be rinsed out of most filters. Store the equipment in a dry area.
You may want to visit a commercial maple producer to pick up tips on how to make syrup. Many producers hold open houses during the spring and will welcome your questions.  To see what sugarhouses are open near you visit and click on Maine Maple Sunday.

How to Prune Blueberry Bushes

Excerpted from Growing Highbush Blueberries, Bulletin #2253, prepared by David T. Handley, Extension vegetable and small fruit specialist, University of Maine Cooperative Extension

Blueberry bushes should be pruned every year to in order to keep them producing high yields of good quality fruit. Prune the plants when they are fully dormant during the late winter or early spring (January-March). For the first two years after planting, simply remove any dead branches and all weak, spindly growth. For plants that have been established for three years or more follow these four steps:

  1. Prune out any weak, low-growing or diseased canes.
  2. Prune out all canes that are over six years old (these are usually the thickest canes, which are gray in color with peeling bark). Blueberry canes tend to be less productive once they get more than six years old and should be pruned out in favor of younger, more productive canes. Cut the old canes to the ground level unless new cane growth has been sparse, in which case leave a four to eight inch stub above the ground.  New canes may sprout from these stubs.
  3. Thin the remaining canes, leaving those with the most vigorous shoot growth (long, thick branches with good fruit buds). Leave six to seven vigorous two to five-year-old canes and two or three one-year-old canes per bush.  A mature blueberry plant should have six to ten healthy canes varying in age from one to six years old.
  4. Remove any weak fruiting shoots on the remaining canes, especially those under six inches in length. Most fruit is produced on vigorous one-year-old shoots on healthy two to five year old canes.  The fruit buds on these shoots are large and teardrop shaped. Each bud will produce a cluster of five to eight flowers.  The shoots also have smaller, pointed buds that will produce leaves.

diagram showing how to prune a shrub

How to Prune Raspberries

Dormant pruning of raspberries should be left until the late winter or early spring. The first step in the pruning process is to remove canes that have emerged outside of the desired one and a half foot row width. This narrow row width will assure adequate light penetration and air circulation to promote healthy cane growth and reduce disease problems. Next, remove all of the old canes that fruited the previous summer. These have gray, peeling bark and branches (they are dead and won’t fruit again). Also remove any canes that are showing signs of insect or disease injury. Only the most vigorous canes, those with the greatest height and basal diameter, should be left in the row. Thinning should continue until only four to five canes per foot of row length is attained. These remaining canes should be attached to the trellis wires. Finally, all of the prunings should be removed from the field.  These may harbor diseases and insects that may attack the healthy canes.

diagram showing how to thin raspberry canes

For more information about pruning and growing raspberries, see Growing Raspberries and Blackberries, Bulletin #2066, prepared by David T. Handley, vegetable and small fruit specialist, University of Maine Cooperative Extension.

University of Maine Cooperative Extension’s Maine Home Garden News is designed to equip home gardeners with practical, timely information.

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Maine Home Garden News was created in response to a continued increase in requests for information on gardening and includes timely and seasonal tips, as well as research-based articles on all aspects of gardening. Articles are written by UMaine Extension specialists, educators, and horticulture professionals, as well as Master Gardener Volunteers from around the state, with Professor Richard Brzozowski serving as editor.