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Gardening TechniquesAshes bad for garden
Catalogs for gardeners
Fire prevention
Frost protection, what covering
Leach field garden
Lilac propagation
Handicapped access designs
Plastic sheeting isn't really mulch
Plastic sheet mulch: black or clear?
Raised bed gardening for elderly
Soil-free growing (hydroponics & other techniques)
Ashes bad for garden
Q. Would the burnt dust from a charcoal barbecue help enrich the soil in my garden and, if so, how much of the dust would be beneficial? It seems like a good way to recycle my barbecue refuse.
A. The usual answer to questions about using wood ash to enrich soil in New Mexico is—DON’T DO IT! Now, if you are in the mountains and have a low pH soil (rare even in the mountains in New Mexico), it is possible to use the wood ashes, but very carefully). Wood ashes contain a lot of salt. The organic material has oxidized (burned off) leaving behind a lot of minerals, especially potassium. This material increases the salt content of our already salty New Mexico soils. To make the situation worse, most New Mexico soils are not deficient in potassium, so we are creating a problem without gaining any benefit. We recommend that the wood ashes be disposed in a manner that does not add them to garden soil (in a landfill or spread over a gravel driveway, etc.). Do not even add them to the compost pile. The only way to be certain that the above warning applies to your soil is to have your soil tested. Look especially at the pH results and saltiness. If your soil is acid, then you can use the wood ashes in the garden. In other parts of the country, especially east of the Mississippi River (and some areas to the west), the soils are acidic and deficient in potassium. In these areas, the addition of wood ashes is beneficial. It is from garden books written for these areas that we will find recommendations to add wood ashes to the garden.
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Black plastic vs. clear
Q. I have always heard that black plastic mulch in the garden warms the soil faster, but now someone told me that clear plastic causes the garden to warm more rapidly. That doesn’t really make sense to me, but that person is very knowledgeable so I wanted to check.
A. Clear plastic does indeed speed the warming of soil, if the garden is in a sunny location, because it allows the sunlight to pass through to the soil, warming the soil directly. It then holds the warmth next to the soil. Black plastic absorbs the light directly and is itself heated. It then must warm the air under it and the air warms the soil. So why do people use black plastic rather than clear plastic? Because weeds can grow very well under the clear plastic in the early spring. The black plastic, but excluding light from the soil, inhibits weed growth.
As the season advances and the weather warms, it is important to remember that the plastic is still functioning. Clear plastic continues to warm the soil into the summer, perhaps making it too hot for the plants you are growing. In fact, a process called solarization uses clear plastic in the summer to heat the soil to a temperature which will kill disease organisms and weed seeds in the upper layers of the soil. Such heat is not desirable at the roots of our garden plants. Clear plastic may be used early in the spring to warm the soil for early planting of warm season vegetables but, especially here in New Mexico, it is important to remove the plastic or cover it with another mulch or reflective material as the weather warms. Black plastic has the potential to burn whatever touches it. The shading provided by the plants and the rapid heat loss from the thin film, the low heat holding capacity of the plastic film, allow us to use the black plastic as a mulching material without the excess soil heating that clear plastic provides.
Mulch is an important tool for limiting weed problems in the garden and in conserving moisture as well as cooling the soil in mid-summer. However, it can be used to speed the heating of soil in the spring to allow earlier planting of plants which need warm soil. Proper choice of mulch material and then its proper use allows us to maximize the benefits.
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Fire prevention 6-00
Q. What can I plant to reduce fire hazards in my landscape? With all the forest fires this year, I want to reduce the risk of fire to my house and heard that the landscape can cause problems.
A. There are things you can plant to help protect your home from the spread of fire in the surrounding environment. Forest and range fires are a problem that is common in New Mexico. Our landscapes can create a buffer between the fire and our homes or they can help bring the fire right to our houses. Succulent plants such as iceplant are good to use near the house in high risk locations. Succulent plants contain a lot of water and are very difficult to ignite. Many common ground covers and many of our common annual flowering plants are also good plants for resisting fire because, when they are properly irrigated, they resist fire.
Some, but not all, of our native desert shrubs should be avoided in beds close to our homes. One of the mechanisms used by these plants to survive our dry environment is the accumulation of flammable resins in these plants. Some of our native plants burn easily and should be avoided as foundation plantings, though they may be used in the landscape farther from the house if other elements of the landscape create a buffer between them and the house. One such element that makes a good buffer is a mowed lawn. Because the lawn is mowed, it provides very little flammable material to carry the fire to the house. If the lawn is well watered, then it is even more likely to provide a good buffer zone between fire and the house.
Vegetables may even be used in the landscape to help shield the home from fire. A well-irrigated vegetable garden is difficult to ignite and should sustain very little fire. Some plants such as corn are more flammable than others like tomatoes or squash. Keep the more flammable plants at a greater distance from the house.
As important as what is planted is what is removed. In forest areas, don't leave a lot of highly flammable conifer trees near the house. Conifers such as junipers, arborvitae, pines, and spruce contain resins that burn easily. These should be kept at a distance from the house. Many of the deciduous shade trees are more desirable near the house because their leaves are more resistant to ignition. However, since even these can burn, they should not be planted so that they can carry the fire up to the house. Keep some distance between them and the house.
This year's events have shown us the importance of a landscape in either protecting our homes or increasing the hazard to our homes. Now, let's be wise about our landscapes and design them to be beautiful and protective.
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Frost protection covering
Q. What is good to cover plants with so they don't freeze? Plastic? Fabric?
A. You can use either fabric or plastic, but fabric may protect a little better. Clear plastic only protects if there is a layer of moisture on the underside. Clear plastic is transparent to the infrared wavelengths of heat. Plastic will also cook the plants in the morning unless it is moved soon after the sun comes up; however, the temperature may still be freezing outside. It is hard to get the plastic to work to your advantage. Black plastic may be a little better, but it will also heat up in the sunlight. Fabrics may insulate better and won't heat as rapidly in sunlight. Light fabrics may not insulate very well. In either case, tie down any covering materials to protect from wind blowing it away. Moist soil under the covering helps protect the plants too.
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Handicapped access designs
Q. I am trying to find links that have garden designs for gardening from wheel chairs and for garden designs for people with dementia. We have some funding available to us to design and implement a community garden that takes into account access for those with disabilities.
Can you help with plans, images, or basic information to help with this community garden project?
A. There are a large number of articles available on the Internet regarding gardens for the handicapped and disabled. I found these using the search terms "garden handicap" and "garden disabled." If you or other members of your planning committee are experienced gardeners, you can adapt much of what is available on the Internet to your needs.
As you construct your garden, be sure to consider the needs of those who will use the garden. Will adults come to the garden, or will children also visit the garden? The design and the selection of plants and construction materials will differ if the garden's visitors are only adults. If children are among those for whom the garden is designed, raised beds should have lower walls to allow the children access to the plants and to reduce injury should the children want to "tight-rope walk" on the walls. Safety should always be a primary consideration in a public or community garden, but this garden requires that safety be of special concern.
Raised beds are good to allow easy access for elderly or disabled gardeners. Benches built into the top of the raised bed walls will allow the gardener to sit while tending the plants. The bed's width should be such that no point in the bed is beyond the easy reach of the gardeners. That means a bed with access from walkways on both sides can be 4 to 5 feet across, but only 2 to 2-1/2 feet if access is from one side only. Gardeners with weak backs and those using walkers will find that such beds will facilitate their gardening. An additional benefit is that the soil in raised beds may be "formulated" rather than just using that which is in the surrounding environment. Here in New Mexico that means we can add organic matter in the form of compost to adapt the soil if needed for better plant growth. Different beds may have different soil formulations to allow xeric plants in one bed and plants requiring more water in another. Plants needing soil with greater acidity can have beds formulated especially for them. Plants wanting alkaline soil can have their own areas.
Walkways in the garden are also important. Muddy paths make wheelchair and walker access difficult. The walkways may be paved with solid paving materials or with porous materials such as crusher fines tamped and treated to form a firm surface, even after rain. This will require that drainage be provided so that the walks do not hold water after rain or irrigation. The width of the walkway should be determined after considering what traffic will occur. Do you need room for 2 wheel chairs to pass while another person is standing next to a raised bed while gardening?
Wheel chair gardeners may appreciate raised gardens with room for their knees and the chair partially under the bed. This may be designed as a box of soil raised on sturdy legs. The front of the bed will need to be shallow to allow room for knees, but the back of the bed may be deeper to allow adequate root depth.
There is much more to consider, but first consider the garden's visitors and their needs with regard to these design factors.
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Leach field garden
Q. I have an open area over my septic leach field and want to plant a garden or orchard in that area. Is that a good idea?
A. In my opinion, it is not a good idea to plant either a garden (vegetables) or an orchard over the septic leach field. Although plants will not absorb human disease organisms through their roots, it is possible that disease organisms would be on the surface of the vegetables (roots, leaves, or fruit) and could cause disease.
Although there is little chance that the disease organisms would be on the surface of tree fruits, the problem with an orchard over the septic field is that of the tree roots clogging the drain lines. It is best to avoid planting trees too close to the leach field since their roots extend a long distance from the trunk, even if the trees are not directly over the leach field.
Perhaps it would be best to plant either a lawn or an ornamental garden of annuals and other flowers which do not have a deep root system over the leach field. This would preclude the use of edible plants or plants with a deep root system which could cause problems.
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Q. Can I grow lilacs from pieces of stem that I cut off after the lilacs finish blooming?
A. I usually discourage people wanting to propagate (increase) lilacs by cuttings, but there is a chance to succeed when you do it at the time you propose. However, you should realize that growing lilacs from cuttings is very difficult.
The new, very tender growths may be removed from the plant soon after growth begins. My resource says that there is a very narrow window of opportunity for taking the cuttings from the plant. This time is when the new growths have reached a length of 4 to 6 inches. If you wait much longer, the chances of success (already limited) become much reduced.
These very tender cuttings should not be allowed to dry before or during the rooting process. Treat the cutting with rooting hormones (indolebutyric acid is recommended at a rate of about 0.8 percent in talc) by dipping the freshly cut end of the cutting into water and then into the talc containing the hormone. Immediately place that cutting into a prepared hole. (Prepare the hole before inserting the cutting so that the talc is not rubbed off.) Firm the moist potting soil around the base of the cutting after it is inserted. Repeat this process with many cuttings so that there is a chance that one or a few will succeed in forming roots. It may take 6 to 8 weeks for roots to form.
During the period of rooting, the cuttings must not be allowed to dry. Since they do not have roots to absorb water, high humidity must be maintained around the cuttings. This may be achieved by several methods. Advanced gardeners and commercial plant propagators will place the cuttings in a mist propagation bed in which a fine mist is frequently sprayed over the plants to maintain humidity. A cold frame, shaded to provide bright, filtered light, may also be used. Care must be taken to maintain humidity during the time that the cold frame is vented to prevent overheating.
Light is important, but too much light can cause excess drying. Row cover material or cheese cloth placed over the cold frame glazing will help reduce heating while still allowing sufficient light for the leaves to photosynthesize. The foods produced by photosynthesis are necessary for the formation of roots.
Gardeners familiar with plant propagation by means of cutting often use "hardwood cuttings" that have completed growth at the end of the growing season. This method is not recommended for lilacs. In many instances, lilacs are grafted. Grafting is much more successful than propagation by cuttings.
Another method of propagation that is useful for lilacs that are not grafted is to dig suckers from around the base of the plant and replant them. These suckers are sprouts that developed from the roots and have formed their own roots. This is perhaps the easiest way for most homeowners to propagate lilacs.
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Plastic sheeting, really mulch?
Q. You recently wrote about the benefits of black plastic mulch versus clear plastic mulch. My question is about whether the mulch is tilled into the soil to capture the sun's infrared rays below the surface...or whether we simply lay the black plastic over the surface of the soil. I always thought of mulch as something that is mixed into the soil?
A. The English language can sometimes be fun, or sometimes a real pain, because it changes so rapidly. I was using the term "mulch" in a traditional sense, as do most professional horticulturists. I have noticed that in recent times many people, especially home gardeners and the media, use the word "mulch" when traditionalists would say "compost" or "soil amendment." I believe the confusion has developed because when we create a mulch from garden trimmings and debris, we encourage people to shred or grind it. This shredding or grinding has begun to be called "mulching" by many people, including some landscape professionals. We also encourage the shredding or grinding (mulching) of garden debris before adding it to a compost pile. Here is where the problem begins to develop. Then, once the compost has been formed by decomposition of the garden wastes, it is applied to the garden. It is usually tilled into the soil but may sometimes be applied to the surface as a "mulch."
This is a further opportunity for "word confusion." The application of the word "mulching" to the grinding process and the use of compost as a mulch has allowed enough confusion to cause many people to call compost "mulch". To a horticulturist, a mulch is a material applied to the surface of the soil to reduce the evaporation of water, to moderate soil temperatures, to reduce wind and water erosion, sometimes even to create an aesthetically pleasing background for the plant, and to limit weed growth. This term, mulch, is the same whether the mulching material is plastic, rocks, sand, or if it is shredded landscape debris. We use the term compost to describe the decomposed organic materials which are added to the soil as a soil amendment. So, the plastic mulches I discussed are to be placed over the surface of the soil and not incorporated into the soil. I apologize for the confusion and appreciate your letter. I am sure you are not the only one who was confused by this terminology. The English language is one in which the correct definition of the word is determined by the majority usage. Someday we horticulturists may need to coin a new word for what we call mulch, but for now, I will explain how I use the word rather than invent new words.
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Raised garden beds good for elderly gardeners 11-00
Q. My grandmother recently had a hip replacement. She is now unable to kneel in her garden. Is there a special seat that can be purchased to solve this problem?
A. I am not familiar with any chair that would facilitate your grandmother’s gardening. Any chair that would be low enough to make gardening easy would be so low that it would be difficult for her to stand. Perhaps there is a power-lift type of chair that I haven’t seen that would work.
I suggest that her gardening be facilitated by creating raised bed gardens. She could sit on the side of the raised bed and reach into the garden. It is important to design the raised bed garden so that she can reach to the center of the bed from either side. If the bed is against the side of a wall or building so she can sit on only one side, then she must be able to reach across the whole bed. Raised bed gardens have many advantages. You can formulate the soil to the needs of the plants that will be grown in the bed. Different beds can have soil adapted to different plants. The design of the raised bed can be attractive, adding an architectural element to the landscape. The soil in raised beds often warms more quickly in the spring than traditional garden soil, allowing earlier planting. Of course, raised beds reduce the bending and kneeling required in traditional gardens.
You should also contact your local Cooperative Extension Service office for more information. If there are Master Gardeners working with your local Extension Service office, they can also make good recommendations.
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Soil-free growing (hydroponics & other techniques)
Q. Can plants grow without soil?
A. Yes, plants can grow without soil, but they cannot grow without the necessities that soil provides. Plants need support, nutrients, protection from adverse temperatures, an even supply of moisture, and they need oxygen around the roots. It is possible to provide these necessary components for plant growth without soil.
Many of us have grown ivy, sweet potatoes, and other plants in a vase containing only water. The vase supplies the support, the water provides mineral nutrients, and an indoor location provides the temperature protection. In the case of plants in water, the oxygen is the greatest problem. Plants that can be grown in water must extract oxygen from the oxygen dissolved in the water. Many other plants will not survive without the extra oxygen provided by the pore spaces in the soil. We often force spring flowering bulbs to blossom indoors by placing the base of the bulb in gravel and adding only enough water to reach the base of the bulb. Oxygen is not the limiting factor. There are few minerals provided by the gravel and the water for these plants. Bulb plants, however, have their own supply of minerals and necessary food stored in the bulb so they grow and flower in the gravel. Under these growing conditions, the bulb is often depleted and should be discarded rather than saved since the food supply in the bulb is depleted. It is also possible to grow plants hydroponically. Hydroponically grown plants are grown in a solution of water containing the necessary plant nutrients. A variety of methods are used to provide support and oxygen for the roots. Since hydroponic plant production is often in a greenhouse or other protected area, temperature control is provided for both the roots and the top of the plant.
Perhaps the most exotic example I have seem of plants growing without soil was at Disney World where plants were grown "aeroponically". These plants were suspended with their roots dangling in the air inside a greenhouse. The line supporting the plants moved, carrying the plants around a horizontal loop. Along a portion of the loop, the roots were sprayed with a hydroponic solution of water and nutrients. Along the rest of the loop, the roots were exposed to the air. Some tropical plants grow in a manner similar to aeroponic culture. These plants (orchids, ferns, bromeliads, some philodendrons and other plants) grow attached to the branches of trees high above the soil. The tree provides support. Frequent rain showers provide the water. Nutrients are provided by composted materials that run down the trunk and branches of the tree during the rain showers. For most of the day, the roots hang in the air, which provides the necessary oxygen. Yes, plants may be grown without soil as long as we provide for the necessities that are missing when soil is lacking.
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Sources for garden catalogs
Q. My friends have garden catalogs that I have never seen. Where can I find out how to get some different garden catalogs?
A. There are several ways to receive some different and very interesting catalogs. The first is to subscribe to a garden magazine. Unless you instruct the publisher otherwise, they will "share" your name with their advertisers. You will begin receiving catalogs from a variety of nurseries and gardening supply companies. You may even receive catalogs from companies specializing in outdoor clothing. Another way is to send a card to advertisers in the magazines. You can subscribe to the magazines, buy them at the magazine racks in book stores or grocery stores, or just go to your local library and read the garden magazines there. There will be numerous advertisements in the magazine, some of them for specialized types of nurseries. Some require that you send money for their catalog; others are free. Those that require money often provide a certificate good for at least that amount on your first purchase. Once you purchase from a nursery, you will be on their mailing list for a long time. Finally, if your friends have a catalog that is of interest to you, just copy the address from their catalog and send a postcard to the nursery requesting their catalog. This is a good time of year to be requesting a catalog. Many of them are being printed now for delivery during the holiday season. You will receive them in plenty of time to place an order before planting time.
Don't forget to check with your local nursery or garden center. If you do not have a nursery nearby, as you travel across New Mexico, check into the nurseries in the towns you visit. You will find many interesting plants, seeds, and gardening accessories right here in New Mexico. If you don't find what you are looking for, ask the nursery if they can get it for you.
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