HowStuffWorks Answers Your Gardening Questions

The pH of soil should be around 6.5 for best growing.
The pH of soil should be around 6.5 for best growing.

In this article, HowStuffWorks answers your gardening questions. You want to plant a garden or cultivate an enviable lawn, but you also want to ensure that the money you invest in it is well spent, right?

To create a beautiful landscape, it's important to know a little about agriculture. You don't have to have a PhD in the subject, but you should be aware of those elements that will guarantee you the best success. From the initial planning stages to maintenance, we've asked the tough questions and given you the simple, straightforward answers.

Q: How should I raise the soil pH from a 5.0 to 6.5?

A: Apply lime in granular form as ground limestone at a rate of 4 to 5 pounds per 1,000 square feet. Repeat in about six months; season is unimportant since lime (calcium) won't burn the plants. It takes a year or so to raise the pH to the desired level, and gradual application works better than one heavy treatment. Have the soil tested again the following year for further recommendations.

Q: What are the most common lawn weeds about which I should be concerned?

A: Naturally, the weeds you'll deal with will be different from those in another region, but general problems will be similar. The best weed control is prevention. A thick, healthy lawn has no bare soil where weeds can become a problem. Broad-leaved weeds -- like dandelion and plantain -- and annual grassy weeds -- like crabgrass -- can be kept under control with herbicides. Annual weeds will die in winter, scattering thousands of seeds for next year's onslaught. Use a preemergenct herbicide in spring to prevent those seeds from sprouting.

Q: How should I eliminate existing moss to rejuvenate the lawn?

A: The presence of moss indicates lack of sunlight and poor soil. Soils where mosses grow tend to be acidic, compacted, poorly aerated, and low in fertility. Remove the moss and freshly prepare the soil. Raise the pH with lime and add a complete fertilizer. Deeply cultivate the soil, adding organic matter and sand if necessary to improve drainage and aeration. Reseed or install sod of a shade-resistant turf species.

Q: When should I cut back my ornamental grasses?

A: Part of the beauty of ornamental grasses is their attractiveness in a winter garden -- the seed stalks and foliage can be enjoyed throughout the winter. Then, just before the grasses begin their new growth, cut the dead part down. Cool-season varieties begin their growth in late winter; warm-season varieties begin when the soil has warmed significantly. To prevent damage to the emerging leaves, cut back the grasses before your plants break dormancy.

Q: How can I sketch my property to scale?

A: First, make a non-scaled sketch of your area, noting the dimensions of existing details. Next, use graph paper to sketch the plan to scale using each square to represent a certain distance (for example, one square equals one foot). Photocopy your sketch so you're able to try several different ideas without having to repeat the process. Remember that plants will grow, so sketch your layout as it would look, say, 10 years from now. By using scale during the planning process, you'll get a better perspective on your garden design.

Q: When shopping for a building lot, what characteristics should be considered to make my landscape planning easier?

A: First, consider your outdoor living areas. Do you need a large, flat area for the children to play? If so, don't buy a steep lot. Perhaps you'll want to plant a vegetable garden, or want another area that requires full sun; a wooded lot might not suit your needs. Use a list of your household's requirements for the property to determine if the lot can fill those needs.

Q: It will be years before our trees grow large enough to shade our deck. Is there anything to do in the meantime?

A: A simple open trellis or arbor overhead will provide support for fast growing vines, annuals such as morning glories, or perennials such as clematis. An overhead structure identifies a comfortable living space while affording protection from the sun. Be sure to build the structure high enough for comfort, while realizing that cascading vines will take space.

Q: I need to make our backyard more private. Should I enclose the yard with a privacy fence?

A: Unless you need to keep people out, or keep children and pets in, you probably don't need the entire yard enclosed. Strategically placed sections or panels of fence in combination with small trees and large shrubs, for example, make for a more aesthetically pleasing atmosphere. An enclosure will make the yard seem small. Take advantage of neighboring trees and gardens to make your yard feel larger.

Q: Is it important to collect the grass clippings when cutting the lawn?

A: Remove excessive amounts of clippings from tall grass, as they will smother and kill the grass underneath. A few species of turfgrass produce a heavy thatch buildup (matted, dead grass) that can prevent water, fertilizer, and air from getting into the soil, thus weakening the health of the lawn. Regular cutting will usually produce only light clippings that will quickly deteriorate -- adding valuable nutrients back into the lawn.

Q: What time of year should I start a new lawn from seed?

A: It depends on the type of grass you plan to grow. Most likely, if you're planting seed, you'll be using a cool-season grass. It's best to prepare the soil at the end of the summer and sow seed about six weeks before the first average frost in your area. The seed will sprout during the remaining warm weeks and continue to develop deep roots through autumn and into winter. By mid-spring the lawn will be well established.

Q: Does it really matter whether I use fresh barnyard wastes and compost as opposed to old, seasoned organic matter?

A: Microorganisms that break down the vegetative matter use much of the available nutrients (especially nitrogen) from the soil. Material will decompose in a compost pile faster than if the matter is directly cultivated into the soils, as the microorganisms also need air. If fresh organic matter is used in or on top of the garden, you will need to apply additional nitrogen to protect plantings from a nutrient deficiency.

On the next page, read more about gardening your questions. From selecting a garden sight to purchasing plants, we've got the answers that will help you grow a lovely garden.

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Gardening Questions

Good shears will last a long time and ensure proper plant growth.
Good shears will last a long time and ensure proper plant growth.

These basic gardening questions and answers will have you successfully planting in no time. Become familiar with the language of gardening, and learn how to select plants that are appropriate for your gardening style and that will thrive in your environment. If you're a beginning gardener, reading up on these questions and answers is a good place to start building the landscape of your dreams.

Q: Which type of pruning shears is best?

A: There are basically two types of pruning shears: anvil and scissors. A good quality pair of shears should last many years. An advantage the scissors type has over the anvil is that it won't crush the stem while cutting. Good shears can be taken apart for sharpening, and replacement parts can be easily obtained for high quality models. Long-handled lopping shears are helpful when thinning shrubs and cutting larger stock than hand pruners can cut.

Q: Although I understand the benefits of using compost in the garden, I will probably never be disciplined enough to build and maintain a pile. What can I use instead?

A: Many municipalities have old piles of leaf mold -- from autumn collection -- that is free for the taking. Arm yourself with a few plastic bags and a shovel and head for the lot. Another option is purchasing composted manure from a stable or barnyard. You can also buy dehydrated manure or compost and incorporate it into the soil as you would with fresh compost.

Q: My neighbors have no problem growing a beautiful camellia, but after many failures, I've stopped planting them. Their soil seems the same as mine.

A: The successful camellia is probably growing in a microclimate that may not exist on your property. A protected microclimate is a good situation to try marginally hardy plant species, since it's protected from extreme daily temperature changes and winter winds. Visit your neighbors' site and try to determine the origin of the unique location -- you may have a site that is equally suitable.

Q: I'm looking for a particular cultivar that I can only find through mail order. Is it safe to buy plants from another temperature zone?

A: If you know the type of plant will grow in your climate, you should have no problem -- if it's a spring purchase. If the nursery's zone is warmer than yours, specify a safe ship date for your area. The newly installed plant will have all summer to acclimate to your seasons, and should survive the upcoming winter.

Q: There are a bewildering number of varieties available of the kind of plant I'm looking for. How do I make a wise decision as to which variety to purchase?

A: Sometimes the color of the bloom is the only difference in variety, making the choice one of personal preference. Other times the differences are more drastic, such as a resistance to a disease that may be prevalent in your area; and still other times the difference may be in the ultimate height, width, or form of the plant. Read nursery catalogs and talk to garden center salespeople to determine which varieties interest you and best suit your conditions.

Q: What does it mean to have "well-drained soil"?

A: Although it's necessary for your soil to have water available for your plants, too much water held for long periods of time will disturb the balance of air that is necessary for healthy root growth of most plant species. Without air in the soil, many plants will likely drown. Loam, a balance of sand, clay, and organic matter, is usually well-drained. Heavily compacted clay soils are often poorly drained.

Q: Being a weekend gardener, I'm not sure I want to spend the energy necessary to double-dig my new perennial bed. What are the advantages?

A: Double-digging provides a better quality soil for the deep roots that many perennials develop. Remember, perennials are long-lived plants, and the time and effort you use to develop a perfect growing environment is well spent. Imagine your investment withering up a few years after planting because the soil 12 inches under the surface is too compact for the roots to develop properly!

Q: How can proper site and plant selection make insect management easier?

A: There are many types of landscape plants that are virtually pest free (or at least pest resistant). Find out which pests are a problem in your area, and steer clear of plants that attract such pests. Additionally, a plant that is growing out of its optimal environment -- full sun as opposed to partial shade -- may not be able to support the beneficial insect predators that normally keep the pests at bay.

Q: I have seen collections of perennials, trees, and bulbs advertised so inexpensively that it's hard to resist purchase. Are such bargains worth the price?

A: Beware of such bargains -- you get what you pay for. The trees, shrubs, and perennials are often no more than rooted cuttings, six inches tall -- and sometimes they're species that won't thrive in your climatic conditions. Bulb collections are often an inferior quality of small size or outdated cultivars; they may take several years to become large enough to bloom.

Q: How do I select which shade tree is the right one for our property?

A: Determine the height, width, and density of shade needed for the site. Also decide how important the rate of growth is to your plan. Consider the environmental conditions -- temperature zone, soil type, light exposure of your proposed tree site, and how much pest control you are willing to use. Take this information and compile a list of possibilities -- with help from catalogs or by talking to local gardeners. Then go to a local garden center or botanical garden to see your choices.

On the next page, discover the answers to many commonly asked gardening questions, and learn about optimal planting conditions.

Want to find out more about growing a flower garden, a houseplant, or a vegetable garden? Check out:

Commonly Asked Gardening Questions

Zinnias add a pop of color to a garden.
Zinnias add a pop of color to a garden.

Commonly asked gardening questions frequently focus on how best to cultivate a garden. When should you plant? Where should you plant? And how should you plant? We've answered your commonly asked gardening questions to help you cultivate a lovely garden, so smile. Things are looking rosy.

Q: I have several large patio containers of trees and shrubs growing with mixed annuals. How do I overwinter these containers?

A: Remove the annuals from the containers at the end of the season. Move the containers to a location protected from the warming sun and winter wind. Insulate the soil with mulch -- compost, bark, or leaves -- and make sure the containers receive adequate water during dry spells. Try planting some spring flowering bulbs in place of the annuals to enjoy some early season color.

Q: I have trouble growing flowers in my shade garden. Are there any colorful shade-tolerant plants that I can use?

A: Aside from using perennials with some bloom, and contrasting color and texture, a few annuals will thrive in the shade given proper moisture and nutrients. The most shade-tolerant annuals that add color all season are coleus (grown for colorful foliage), wax begonias, and impatiens, which are available in a host of colors. Depending on the depth of shade, still other annuals, such as ageratum, sapphire flower, caladiums, and sweet alyssum, may be successful.

Q: When can I safely plant annuals in the spring?

A: From your local Extension Office, find out the date of your area's average last frost. After that date, planting should be safe; but remember, this date is an average and you can expect a later frost some years. When you purchase annuals, condition them to the sunlight, wind, and night temperature for several days before planting them in the garden. Be prepared to protect them from a late-season freeze.

Q: My hanging baskets of annuals look great each spring when I purchase them. By midsummer they look dried up and have few blooms. How can I keep them fresh and full of flowers?

A: Follow three basic principles when growing flowering baskets -- water, fertilize, and groom. The soil mass in a basket is very small -- it heats up and dries out quickly -- so daily watering may be needed. Fertilize the plant with a liquid balanced fertilizer every two weeks. And groom your plant often. Deadhead and pinch back leggy growth to promote heavier flowering and branching.

Q: What should be done this fall to prepare a bed of annuals for next spring?

A: When this year's plants have died from frost, cut them to the ground and, to prevent this year's pests from overwintering, remove all debris from the area. Have your soil tested now -- add lime if necessary but wait until spring to fertilize. Cultivate organic matter into the soil and apply a fresh layer of mulch to prevent winter weeds from germinating. Your bed should be ready for spring planting.

Q: Is it possible to save any of my annuals through the winter for next year's plantings?

A: Several types of annuals overwinter well in the house. Coleus, geraniums, impatiens, and wax begonias hold nicely as houseplants. Dig up the plant with as much of its root system intact as possible and pot it, using quality potting soil. Cut the plant back by 40 to 50 percent, leaving some foliage on the plant. In the house, provide the plants with as much light as possible, keeping the soil slightly moist.

Q: I'd like to grow annuals for cutting and arranging. What types make the best cut flowers and where should I plant them?

A: Look for varieties with tall stems in the colors you'd like to use for arranging. Many species of annuals are available in varieties that have different characteristics. Some will be short and bushy for edging and massing, while others will be tall -- excellent for cutting. It is a good idea to grow them in the back of the border or design a bed especially for cutting. A row or more in a sunny vegetable garden, for example, serves as an ideal place to grow cut flowers.

Q: What is the best way to stake my tall and floppy annuals?

A: Use materials that will be unobtrusive in the garden. Natural brush and twigs blend in well with garden plants; green bamboo stakes are available at garden centers. It is best to set up the stakes during planting time so the roots are not damaged during installation. Tie the plants loosely with string, plastic wrap, or even leaves of tall ornamental grasses. Avoid wire ties, as they easily cut flower stems.

Q: Which annuals require the least amount of maintenance time?

A: Choose varieties that will not require deadheading or much additional irrigation. Some annuals drop their flowers naturally while others put energy into seed production, and must be groomed for continual bloom. Ageratum, alyssum, begonias, dusty miller, impatiens, and vinca are a few self-cleaning annuals. Ageratum, marigolds, ornamental peppers, portulaca, and vinca are among the drought-tolerant species. Prepare your soil well with organic matter (such as wood chips, leaves, or compost) to increase the intervals between waterings and to save maintenance time.

Q: It seems that the only bedding plants available are short varieties suited for the front of the border. What can I do to get some height for the back of the border?

A: A greater selection of varieties is available through mail-order seed catalogs. Some companies sell a large selection of starter plants as well as seeds, but you may enjoy starting your own seedlings. Start small-seeded varieties on a sunny windowsill several weeks before planting outside. Many varieties can be sown directly in the garden.

Q: Do you have any suggestions to help encourage children to enjoy gardening?

A: Success is the best motivator. Encourage children to have a garden space of their own, but work with them to ensure success. Grow plants from large seeds, or use transplants for immediate color. Grow varieties like morning glories and gourds -- quick growing vines which produce abundant flower or fruit -- and colorful zinnias, or balsam. Encourage the child to collect seeds to save for next season. Most of all, go out and enjoy the garden together!

On the next page, learn how to maintain your plants so you can enjoy them year after year.

Want to find out more about growing a flower garden, a houseplant, or a vegetable garden? Check out:

Gardening Questions Answered

Crocus bulbs will flower after they have established their root system.
Crocus bulbs will flower after they have established their root system.

We've got your gardening questions answered right here. If you have questions about perennials, bulbs, and fertilizers, we've got answers. Find out the difference between inexpensive and expensive plants, how to protect your plants, and how to coax your plants to bloom. With this information, you'll be armed with knowledge to help you grow a beautiful garden.

Q: It's late winter and I've not yet planted the spring-flowering bulbs purchased last fall. Can they still be planted?

A: Spring flowering bulbs need the winter to establish new root systems and to finish development to bloom. If the bulbs are not spongy -- an indication of a dying bulb -- you should still be able to grow the bulbs; just don't expect flowering the first year. Care for the plants with fertilizer and regular waterings. If the plant is able to build back its strength, it will probably flower the following season.

Q: It's mid-winter and my bulbs and some perennials are beginning to emerge. Should I cover the plants to protect them from the elements?

A: Bulbs and perennials usually begin their growth at the right time, and are prepared for additional cold weather. Remove a bit of the mulch from around the plant. This will cool the soil and slow some of the growth. Just allow the plants to grow naturally and they'll bloom when the time is right.

Q: When is the best time to dig and separate bulbs?

A: The foliage of most spring bulbs will naturally turn yellow about six weeks after flowering. This is a good indication that the plant has produced and stored enough energy to survive and bloom next season. When leaves have begun to turn yellow, dig deeply to remove the entire clump. Gently shake the soil from the bulbs and break individual bulbs from the clump. Immediately replant the bulbs.

Q: After several years in a sunny location and well-drained soil, my peony hasn't bloomed. What's wrong?

A: Your plant is probably planted too deeply. Dig the plant in early fall and inspect the roots for any unusual damage. Adjust the pH to between 5.5 to 6.5. Replant so that the crown -- the part where the buds form -- is one to two inches below the soil surface. Water deeply and apply mulch so the plant can reestablish itself.

Q: When do I divide clumping perennials such as coralbells and Japanese iris?

A: Most perennials divide easily in fall, if done early enough for the roots to establish themselves several weeks before the ground freezes. Late blooming types can be divided in spring, providing there is ample rain or irrigation to encourage rapid rejuvenation of the root systems. Expect a reduction of flowering until the plants become reestablished in their new positions.

Q: What is the difference between inexpensive perennials grown from seed and the more expensive ones grown from divisions?

A: Some perennials are easily grown from seed, and produce flowers within a year or two. However, named cultivars -- plants with specific desired characteristics -- may only be reproduced through cuttings or by division from the parent plant, which displays the unique features. Because it takes longer to produce quantities of plants by division than by seed, production of these cultivars is usually more expensive.

Q: How can I keep spreading perennials like Monarda from invading my more timid plants?

A: Control invasive perennials by forming a barrier around the parent plant. The barrier needs to be set in the ground deep enough to prevent the rhizomes from growing beneath it. Use a large black nursery container with its bottom cut out; sink it in the ground to about 1/2 inch higher than soil level. Plant in the center of the pot and disguise the rim with a light layer of mulch.

Q: Most of the perennials have finished blooming, and I'd like to clean up the garden. How far down can I cut the plants?

A: It's important to leave the crown of the plant undisturbed so the basal leaves can continue to grow and produce food for the plant's winter survival. Cut flowering stalks to about four inches. The remaining stubble will identify the plants' locations so that you won't disturb them during bulb planting or winter gardening.

Q: What is the best method of fertilizing a perennial border of many different types of plants?

A: If the soil is properly prepared with organic matter, and the bed is mulched, only an annual application of complete fertilizer is needed. In early spring, when the plants actively begin growth, sprinkle fertilizer on the soil. Apply by hand to avoid fertilizer settling on the leaves. Use the directions on the bag to calculate the amount to apply.

Q: Why do some of my "full sun" selections of perennials burn up in my southern garden?

A: Garden books categorize light requirements of perennials according to the average light intensity of North American gardens. Plants that need full sun in New England may need protection from the hot afternoon sun in Georgia. Use references to guide your planning, but the best advice comes from experimenting with different species under various light conditions. Also, the use of mulch will aid in keeping soil temperatures lower.

On the next page, learn all about how to plant and care for trees, including your old Christmas tree.

Want to find out more about growing a flower garden, a houseplant, or a vegetable garden? Check out:

Tree Questions

Only female holly produces berries.
Only female holly produces berries.

If you have questions about trees, we've got answers. Trees require different care and maintenance than plants. They also develop different symptoms of illness. If you want to know how to plant, prune, and protect your trees, read on.

Q: Why does my wisteria never bloom? It grows so quickly that it must be pruned often.

A: You may be pruning off next year's flower buds. Encourage short side shoots for flower buds by partially pruning the longest side branches. To avoid excessive growth, do not fertilize wisteria. Wisteria blooms best with ample exposure to the sun. Root pruning may shock the plant into flowering -- in June, use a spade to cut a six-inch deep circle about two feet from the base of the plant.

Q: When should I prune my trees?

A: Pruning shade and ornamental trees not only adds to the aesthetics of the landscape, but prolongs the life of the tree. Prune to thin out branches in late winter when the sap is rising. The sap "bleeding" helps prevent disease organisms from entering the wound and the tree will heal quickly at this time of year. Limbs that need to be removed because of storm or disease damage can be pruned any time of year.

Q: To receive more light into the yard, should I have the trees topped?

A: Topping not only disfigures a tree aesthetically, but drastically degrades its long-term health. The large, open wounds that topping creates will not heal completely, allowing easy entrance to disease-causing organisms. Rapid, dense, shoot growth (called suckers) grow to the original height of the tree, consequently defeating the purpose of topping. The new growth will not be as structurally sound as normal branching, becoming more susceptible to storm damage.

Q: I have several hydrangeas, all of which are the same kind. Why are some blue flowering while others are pink?

A: The availability of aluminum in the soil, determined by the soil's pH, determines the color of your type of hydrangea. If the pH is high (7.0 or above), the flowers will be pink. Blue flowers develop from acidic soil (4.5 to 5.5), and purplish flowers in between. To ensure blue flowers, lower the pH with a sulfur-based product. Raise the pH with lime for pink blossoms.

Q: Can a live Christmas tree be planted after the holidays?

A: Yes. Prepare the hole well before the ground freezes. Amend the loose soil as you dig so it will be ready for planting, and store the soil where it will not freeze. Choose a tree with a tight, solid root-ball and wrap the ball in plastic to keep moist while it's in the house. A cool room for no more than a week is advised. Plant the tree as soon as possible; mulch and water well.

Q: What causes the bark of young trees to crack, and how can it be corrected?

A: The vertical cracking, or sunscald, appears on the southwest side of the trunk; where the tree heats up on warm, sunny, winter days, and freezes rapidly when the sun sets. Young trees are most prone to sunscald because of their thin bark. These cracks provide a path for diseases and insects. Sunscald can be prevented by wrapping the trunk in a protective covering for the winter. Expandable, white plastic tree wraps are available at garden centers.

Q: What makes some hollies produce berries when other don't?

A: Hollies are either male or female; only the females produce berries. A pollen-producing male plant needs to be growing nearby to pollinate a female, otherwise berries will not form. Although some species can pollinate other species, it's generally necessary to have both a male and a female of the same type. Other reasons for lack of fruit include a shortage of sunlight where the female is planted, or severe drought while berries are forming.

Q: Is it possible to transplant trees from the woods to the yard?

A: Although it's possible, the success rate is low. Forest tree roots are quite entangled with other trees; either with wide-spreading shallow roots, or a deep taproot, depending upon species. The tree is already acclimated to the woods exposure. Both the shock of transplanting and the loss of roots often kill the tree. Nursery-grown trees have been tended by root pruning to encourage the development of a small but concentrated root system, making transplanting more successful.

Q: Is it possible that road salt is killing the shrubs at the end of my driveway?

A: Salt toxicity is common in areas where deicing salts are used in winter. The worst damage occurs right where the salt is applied, near roads and walks. Plants will display general dieback, yellowish foliage, and weak growth. Wash salt residue from plants with a hose, and soak the soil to leach the salt from the beds. Don't use salts around the home. Some fertilizers can be safely used to melt ice and will not harm nearby plants.

Q: Is it necessary to stake newly planted trees?

A: If the crown of the tree is relatively large compared to the size of the root ball, staking may be needed to prevent the tree from tilting as it settles. Be sure the root ball sits on a firm soil base. Tie with flat plastic guy string or wire covered in old garden hose to protect the bark from being cut or wounded. Remove stakes and wires as soon as the tree roots become established. Evergreen trees do not usually require staking.

Want to find out more about growing a flower garden, a houseplant, or a vegetable garden? Check out: