Maine Home Garden News
April 2009

April is the month to . . .

• As the snow leaves your lawn, rake out any mole hills.  Reseeding is probably not necessary in these areas. Moles are carnivores and are attracted to your lawn area by underground grubs, earth worms and insects. The University of Arkansas has an informational fact sheet on effective mole control: "Controlling the Eastern Mole" (FSA-9095). Download it for free from their site or call UMaine Extension at 1-800-287-1471 for a copy of the fact sheet.
• Remove mulch from plantings such as herbaceous perennials and strawberries. Allow the plants to receive sunshine as the weather and soil warms.
• There’s probably still time to prune fruit trees and blueberry plants before they break dormancy. Be cautious as your pull or remove cut branches from the tree/bush so as not to damage buds on remaining branches.
• As the soil thaws, consider getting your soil tested. Are there specific gardens or lawn areas that did not perform well last growing season? A soil test can provide useful information to make this growing season more production. Contact your local UMaine Extension county office for soil testing forms, boxes, and fact sheet, or see the Maine Soil Testing Service. Some UMaine Extension county offices have soil sampling probes for borrowing. The probes make soil sampling faster and easier. The price for a soil test from the Maine Soil Testing Service has recently increased to $15.00 per sample but it is still cost effective. Make your liming and fertilizing decisions on real facts not by the seat of your pants.
• Inspect trees and shrubs in your landscape and prune out any damaged or dying branches. Winter can take a toll on plants. Use sharp pruning tools.
• Consider purchasing new pruning tools needed to work effectively such as hand shears, loppers, pruning saw, or pole pruner.
• If you have not done so already, start planning your vegetable garden. What do you want to grow?  What vegetables does your family enjoy eating? How much should you grow? There are some frost tolerant crops that can be planted in April if the snow is gone and the soil is workable.
• Consider extending your growing season this year by planting some cold hardy vegetables well before the traditional planting time of Memorial Day weekend. These vegetables include broccoli and cabbage by transplants, onion sets, as well as endive, lettuce, peas, radish, spinach, and turnip by seed.
• Rake out and level any turf areas damaged or disturbed by the snow plow. Do some spot seeding if necessary. Garden centers generally have a suggested turf seed blend for such situations.
• Encourage a friend to garden this year. Gardening is a great way to stay active, be outdoors, socialize, and enjoy nature.
• Help individuals in your neighborhood or community who might need assistance with their garden this growing season. People who lack the physical ability to garden by themselves due to age or disability appreciate others who lend support. You would be surprised at the friendships you can cultivate!

By Richard Brzozowski, Extension Educator, Cumberland County, Maine; rbrz@umext.maine.edu

Gleason Gray at the arboretum. Photo by Edwin Remsberg, USDA.

Backyard Greenhouses
By Gleason Gray, Extension Educator, Penobscot County; ggray@umext.maine.edu

A backyard greenhouse can take any one of several forms. It can be a stand alone structure or be attached to an out building or to the home.  It can be designed for growing crops in the ground or growing on benches. It can be a heated or unheated structure. It can be in a fixed location or movable for crop rotations when used for in ground growing.  When planning for a backyard greenhouse there are a few things to think about before and during the planning, construction, and use of the structure.

1. Know why you want a greenhouse:

   • Is it to grow spring transplants?

   • Is it to grow vegetable crops in the ground?

   • Is it to keep plants growing all year for ornamental use?
      

2. Select an appropriate site:

   • A greenhouse needs full sun to provide optimum growing conditions.

   • The site should be well drained to avoid wet soils and spring flooding.

   • The greenhouse should be close to needed utilities like power and water.

   • The structure should be located so it does not interfere with other activities.
      

3. Build your greenhouse is large enough:

   • Try to estimate how much space you need for the crop(s) you plan to grow.

   • Add at least 25% to your estimate because a first greenhouse is never large enough.
      

4. Do not overcrowd your greenhouse:

   • Be sure plants are properly spaced in the greenhouse.

   • Plants that are crowded get leggy reaching for light.

   • Plants too close together do not get adequate air flow around the plants increasing the chances of disease problems.
      

5. Remember  that environmental control is important in all seasons:

   • The structure must protect the plants from freezing.

   • More importantly, small green houses overheat very easily in all seasons so adequate ventilation is critical to the success of the crops.

   • High humidity promotes diseases so ventilation to remove excess moisture is important in all seasons.

There are many excellent greenhouse kits available for back yard use. A quick Internet search will yield a large number of vendors and a wide variety of structures in all price ranges. If you do not have access to the Internet, your local library probably does. I suggest such a search as a great starting point for deciding on what type of structure might suit your needs. It is also a good source of design ideas if you want to design and build your greenhouse without a kit. Be aware that the total cost of materials may equal or exceed the price of a kit.

When evaluating structures, remember that we live in snow country and you need to make sure the structure you select can withstand our snow loads. Also be aware that truly adequate ventilation for warm season use is a must, so compare the types of ventilation systems offered and select one that will provide adequate cooling. If you have questions about a particular structure, contact someone familiar with greenhouses for their opinion. You can call your local University of Maine Cooperative Extension office for advice or you can contact me at the UMaine Extension Penobscot County office in Bangor (207-942-7396 or toll free in Maine at 1-800-287-1485). The UMaine Extension publication catalog also offers an excellent reference: Greenhouses for Homeowners and Gardeners (Item #1051) for $30.

Growing in a backyard greenhouse can be very rewarding, but it also requires a higher level of management than growing in an outside garden area. So be prepared to become familiar with all of the needs of the crops you hope to grow and of all of the pest problems that can thrive in a greenhouse. A small growing structure provides a uniform set of environmental conditions, which will often limit the diversity of crops that can be produced successfully in a single structure. Attempting to grow multiple crops with widely differing needs will usually result in failure of at least one of the crops.

Select a structure that will meet your needs. Be aware of the needs of the plants you are growing and manage the environment in the greenhouse carefully. You will then enjoy many seasons of highly successful plant production.

Extending the Gardening Season
by Marjorie Peronto, Extension Educator Hancock & Washington Counties; mperonto@umext.maine.edu
Photos by Dr. David Handley, Small Fruit & Vegetable Specialist

Many vegetable crops are very sensitive to cold weather, and the majority of them grow only during the frost-free months of the year. This greatly limits the length of the growing season in Maine. There are several methods that you can use to help protect your plants from the cold and extend our short growing season.

Materials such as plastic mulches and row covers can speed up crop development and allow you to harvest earlier by raising soil temperatures or daytime air temperatures around the plant. Structures such as cold frames and hoop houses can extend the growing season at its beginning and end. Surrounding individual plants in the garden with hot caps, such as insulating plastic water tubes or wax paper caps, can keep your plants a few degrees warmer during cold nights and speed up growth.

Plastic Mulches

Plastic mulches help conserve soil moisture, reduce soil erosion, and inhibit weed growth. The most commonly used plastic mulches in Maine are black plastic mulch and infrared-transmitting (IRT) mulch. When stretched tightly over the garden soil surface, they warm the soil, leading to earlier harvest and increased yields, which is most helpful with heat-loving crops like melons, peppers, and tomatoes. They also improve the quality of your harvest by keeping the edible portions of the plants off the ground.

When applying plastic mulch, follow these steps:

1. Smooth the soil evenly. Make sure the soil is moist.

2. Stretch the plastic tightly over the soil, and bury all edges.

3. Cut or burn planting holes in the plastic.

4. Plant seedlings or seeds through the holes.

5. Since colored plastic mulches are left on the soil for the whole gardening season, check soil moisture regularly, and water as needed through the planting holes. Better yet, before laying down the plastic mulch, install a simple drip irrigation system to keep the soil evenly moist.
   
   
   Black plastic row cover

In order to get good soil warming with plastic mulch, make sure it is pressed flat for good contact with the soil surface.

Row Covers

A row cover is put over the growing plants to create a greenhouse effect. Row covers are made either of perforated plastic or of spun-bonded or woven synthetic materials. They enhance growth by raising daytime air temperature around plants by up to 10°F, and insulate the plants with residual heat at night. They offer some wind and frost protection, and provide a barrier to pests. It is important to secure all edges when installing them so that they don’t blow around. However, you will need to remove the row covers for pollination. If handled and stored properly, they may be used for several seasons.

Spun row cover

Spunbonded or woven row covers are lightweight, white fabrics that allow air, water, and sunlight to pass through. This type of row cover can be supported with hoops, or laid loosely over plants and allowed to “float.”

Black plastic row cover

A slitted or perforated plastic row cover must be supported by wire hoops. Excess hot air can escapes through pre-cut slits or holes. It is commonly used in combination with black plastic mulch for weed control. Monitor temperature carefully to avoid overheating on sunny days.

Cold Frames

A cold frame is simply a bottomless box placed over the plants, with a glass or clear plastic top that lets in the sunlight and opens to allow ventilation. It can be built from a variety of materials. It is generally used to harden seedlings off and protect direct-seeded crops from cold temperatures. Cold frames offer a greater degree of frost protection than floating row covers, but if not monitored carefully, they can overheat. When using a cold frame, be mindful of the following:

• Select a site with well drained soil.

• Orient the glass face towards the south/southeast.

• Monitor the temperature inside the frame and adjust the opening to ventilate and prevent overheating.  Consider investing in automatic openers.

Cold frame

Hot Caps

A hot cap is a cone-, bell-, or tent-shaped individual plant cover that acts as a miniature greenhouse, trapping heat from the sun. These types of covers raise soil and daytime air temperatures, accelerating germination and plant growth while providing some frost and wind protection. Wax paper hot caps shelter plants from wind and discourage insect pests, but they also greatly reduce light transmission to plants. Insulating plastic water tubes keep the air around the plant several degrees warmer. However, these covers are costly and labor-intensive, so they are practical only for small plantings of high-value crops. These are often sold under the trade names Wall O’ Water and Kozy Coat.

Wax paper hot caps

Insulating plastic water tube

© 2009

Published and distributed in furtherance of Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture cooperating. Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Call 800-287-0274 or TDD 800-287-8957 (in Maine), or 207-581-3188, for information on publications and program offerings from University of Maine Cooperative Extension, or visit www.extension.umaine.edu.

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