When to Plant
Container-grown plants and balled and burlapped (B&B) plants with well-developed root systems can be planted throughout the year. However, most B&B plants are dug and planted during the cooler months after leaf drop. Red maples, crape myrtles, hollies and Southern magnolia can be dug at certain times during the summer. Innovative methods of digging during the winter and then potting the B&B trees for subsequent sale during the summer have begun in South Carolina.
As stated, container grown plants can be safely planted at any time of the year, but they are best planted in the fall to take advantage of the dormant season root growth. Unlike the tops of ornamental plants that go dormant and cease growth for the winter, roots of ornamental plants in the Southeast continue to grow throughout the warmer fall and winter months. Fall planting allows the carbohydrates produced during the previous growing season to be directed to root growth since there is little demand from the top. This additional root growth may lessen the dependency of the plant on supplemental irrigation the following summers.
Trees and shrubs must be planted at the right depth and receive the right amount of water if they are to establish themselves and flourish. Planting too deeply and under- or overwatering are among the most common and serious planting errors.
Soil Preparation
While shaping the final grade of the planting beds, remember the importance of good drainage. Poorly drained soils are a leading cause of plant problems in the landscape. Therefore, before placing the first plant in the ground it is important to take steps to assure adequate drainage.
If a site is known to be poorly-drained, create raised beds. Often beds can be elevated 8 to 12 inches above the existing grade by using native soil on site, but sometimes it is necessary to bring in additional well-drained soil. In extreme cases, you may have to install a drain tile to help carry water off the site.
In shaping the final grade, avoid leaving dips or pockets where water is likely to stand. Shape beds so that excess water will be carried off the site and away from buildings. Water also can be directed to unplanted areas. Few ornamental plants, with the exception of pond plants, can tolerate long periods of standing water. Good drainage is critical for most ornamental plants.
If you are planting around new construction, remove any debris left on the site that may cause plant growth problems. Chunks of concrete, roofing shingles, globs of tar, oil spills and sheetrock are a few of the hazards of new construction sites. These can result in long-term growth problems. Soil compaction is also a problem near new construction. Tilling deeply and incorporating organic matter is often sufficient to loosen hard compacted soils.
Soil Test
In addition to examining the physical properties of the soil and taking corrective measures on poorly drained soils, a soil test will determine which nutrients need to be applied and whether you need to adjust the pH. A soil sample is best taken several weeks before planting so you will know how to treat the soil at planting time. However, if new soil is brought onto the site at planting time or if soil is moved around during the final grading, it is best to wait until all the soil is in place before sampling. You can adjust pH or surface-apply fertilizer at the recommended rate later, after plants are established. Soil testing is available at a nominal fee through county Extension offices.
The majority of ornamental plants prefer a soil pH from 5.8 to 6.5. Above or below this pH range, nutrient deficiencies often result. To raise the pH level of an acid soil, dolomitic lime is usually added, while the pH level of alkaline soils can be lowered with amendments like sulfur or aluminum sulfate. Adjusting soil pH without the benefit of a soil test can result in nutrition problems that are difficult to counteract and correct. Follow soil
test results.
Organic Amendments
Organic amendments such as composted products are applied to soils to improve the nutrient and water-holding capacity of soils, or, in general terms, to improve soil tilth. Research has shown that when adding organic matter to a soil, it is best to incorporate it throughout the rooting zone as opposed to placing it in the planting hole. By incorporating an amendment uniformly in the soil, the entire rooting area becomes a uniform growing environment for roots.
On the other hand, when a planting hole alone is amended, the structure of the soil in the hole can differ significantly from that of the surrounding native soil, if an excessive amount or the wrong type is added. This can encourage the roots to stay within the confines of the hole and discourages them from entering the surrounding native soil, especially if a perfectly round planting hole is dug.
Some types of organic materials and quantities of them can also upset the water equilibrium between the surrounding native soil and the soil in the hole. Fine-textured organic matter such as peat moss, placed in the planting hole can act like a sponge in a bathtub, holding too much moisture after rain or irrigation. Coarser-textured material, such as composted pine bark, is less likely to hold excess moisture. In heavy clay soils, use a shovel or mattock to notch out the sides of the round planting hole. This will enable growing roots to more easily enter the surrounding soil.
Organic matter should comprise approximately 10 to 20 percent of the total soil volume. For example, preparing a bed 8 inches deep requires the addition of about 1 to 2 inches of organic matter such as compost, leaf mold, or composted pine bark. Drainage can be improved in clay soils by subsoiling or deep tilling prior to adding organic matter.
Composted materials immediately provide organic matter to the soil. Do not use uncomposted bark products as amendments. Freshly milled bark that has not been composted will slowly rob plants of nitrogen when used as an amendment. As microorganisms in the soil feed on bark and decompose it, they will use nitrogen in the soil. Also, the pH of the soil often drops dramatically below the desirable range when uncomposted materials are used as amendments.
Well-composted organic products have a rich, earthy smell, a crumbly appearance, and the original organic materials are no longer recognizable. For the best choices of composted material, choose either well decomposed material from your home compost pile, or purchase composted pine bark. The composted pine bark may still contain some small bark chips, but this can aid in improving the internal drainage in fine-textured clay soils. Additionally, composted pine bark may help suppress certain soil borne disease causing organisms.
How Deep to Plant
Trees and shrubs must be planted at the right depth and receive the right amount of water if they are to establish themselves and flourish. Planting too deeply and under- or overwatering are among the most common and serious planting errors.
In well-drained soil, the planting hole should never be dug any deeper than the height of the root ball. This means that the soil at the bottom of the hole is left undisturbed. Setting the root ball on loosened soil will cause the tree to settle and sink too deeply into the soil. Locate the topmost layers of roots in the root ball so that it will be level with the soil surface. Check to be sure that there is not an excess layer of soil (or container media) already covering the root ball. As little as a half-inch of excess soil over the root ball can inhibit or prevent water from entering the root ball, especially on trees planted from containers. Only mulch should be placed over the root ball. In well-drained soil, the planting hole should be at least twice and preferably five times wider than the root ball. Roots will grow more quickly into loosened soil, thus speeding up the tree’s establishment time.
In poorly drained or compacted soil, the plant is best placed higher than its original planting depth at about 2 to 4 inches higher than the surrounding soil. Be sure to build the soil up beside the root ball so that the sides are not exposed, and do not place additional soil on top of the root ball. This will allow oxygen to reach the roots in the upper surface of soil. It will also cause excess water to drain away from the plant rather than collecting beneath it. Do not disturb the soil under the root ball to prevent any later settling, which will move the plant roots deeper into the soil. The top of the root ball may dry out quickly in the summer on some sites, so be prepared to irrigate accordingly.
Preparing and Setting the Root Ball
Trees and shrubs grown in plastic or other hard-sided containers can be removed from their containers and placed directly in the holes prepared for them. Cut any circling roots so they will not strangle the tree later on. If a tree or shrub is pot-bound, use pruning shears or a serrated knife to make slices 1 to 2 inches deep going from the top of the root ball to the bottom. Make these slices in three or four places around the root ball. Pull the roots growing along the outside of the root ball away from the root ball. Research has shown that although this kind of pruning does not increase root growth after planting, slicing root balls, whether pot-bound or not, enhances the distribution of regenerated roots in the surrounding landscape soil. New roots grow from behind the cut ends.
When preparing the hole for a bare-root tree, dig it wide enough so that roots can be spread out. Do not cut or break roots or bend them in order to fit the hole. Use a sharp pruning tool to cut or trim any roots that are obviously dead, injured or dried.
Spread the roots out and position the topmost root just under the soil surface. Shallow roots either may be parallel with the soil surface or angled slightly downwards. Some people spread the roots over a mound of firm soil in the planting hole and carefully place soil between groups of roots; others wash soil between the roots.
Natural or synthetic burlap is used on trees that are balled-and-burlapped (B&B). To determine which type has been used, hold a match to a small portion of the burlap. As a rule, natural burlap will burn and synthetic will melt.
Synthetic burlap will not decompose in the soil and can cause roots to girdle the tree. Because this could ultimately strangle the tree, remove synthetic burlap entirely. After pulling burlap away from the sides of the root ball, tip the root ball to one side and push the burlap underneath it as far as possible. Then tip the root ball to the other side and slide the burlap out from under it. The tipping should be performed by handling the root ball; pushing on the trunk of the tree could crack the root ball. When a wire basket is holding synthetic burlap in place, cut away the basket to remove the synthetic burlap, or, if the lower portion of the basket must be left intact, cut an “X” in the burlap in each section of the basket.
Natural burlap is biodegradable and can be left along the sides and bottom of the root ball, but should always be removed from the top of the root ball where it is subject to drying out. Dry burlap repels water, making it difficult to rewet the root ball. In poorly drained areas, remove the natural burlap entirely, if possible, to prevent it from holding too much moisture near the roots.
Wire baskets and wire wrapping are frequently used to help hold a B&B root ball intact during shipping and handling. Trees that are stored after being dug with a tree spade are also placed in wire baskets. This is an effective means of keeping roots in contact with soil until planting. Remove at least the top portion of the wire basket after the root ball is in place.
Filling the Planting Hole
The soil used to fill in around the root ball of the newly planted tree or shrub is called backfill. Your best backfill will be the loosened original soil from the planting hole mixed with 10 to 20 percent compost.
Loosen and break up any clods of soil before backfilling. Clods in the backfill create detrimental air pockets around the root ball and could hinder root growth and establishment. Place the plant into the planting area or hole at the correct depth, and then backfill the bottom half of the space around the root ball.
Tamp the soil lightly with your foot. If amendments are not used, do not tamp so heavily as to compact the soil. Finish filling the hole with loose, unamended soil, and gently tamp again.
Construct a 3-inch-high water ring around the edge of the root ball to hold irrigation water. Initially the root ball will need to be watered directly because roots have not yet spread into the surrounding soil.
Pruning at Planting
Little if any pruning should be necessary at the time of transplant. Do not prune a B&B plant to compensate for root loss. Research indicates that pruning does not help overcome transplant shock unless the plant is receiving insufficient water.
Branches that are injured, diseased or dead may be pruned but are also an indication of a poor-quality tree. It would be best to exchange it for a healthy one.
Trees with poor structure should be pruned at planting to correct the problem, especially if no further pruning is planned for the next year or two. Poor form should not be permitted to develop, as it will become increasingly more difficult to correct. On trees with adequate form, begin pruning for structural development a year or two after planting.
Mulching
Apply 2 to 4 inches of organic mulch over the planted area. Do not allow mulch to touch the stem or trunk to reduce chances of stem rot. Mulching helps to eliminate weeds, retain moisture in the soil, moderate soil temperatures, and eventually adds to soil organic matter content. It also helps decrease erosion of raised soil around plants that are planted above the soil level. Some commonly used mulches include pine needles, pine bark, hardwood bark, wood chips and partially ground leaves.
Watering
Initially the root ball will need to be watered directly because roots have not yet spread into the surrounding soil. The raised soil water ring will help concentrate the water in the root ball area. Water the plant slowly and well after mulching. It is important to note that many plants die from too little or too much water during the first few months after planting. Plants in well-drained soil often get too little water, and those in poorly drained soil get too much water.
Become familiar with the planting site, and try to maintain constant moisture (not saturation) in the root ball for the first few months after transplanting. Some sites dry out more quickly than others and will require more watering. Water rings should be removed by the end of the second growing season if they have not settled on their own. Good watering practices result in plants that establish more rapidly and thus become more quickly resistant to drought, pests and disease.
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Trees and shrubs are living investments that grow in value with each passing year. When properly selected and planted, trees and shrubs can be expected to thrive with the right care, which may include watering, fertilizing and pruning. Just as certain established drought-tolerant plants may not require water during dry spells, mature trees and shrubs growing in favorable soil conditions may require little or no fertilizer.
Fertilizer is often misunderstood and misused. Fertilizer is not “food.” Plants produce their own food in the form of sugars through photosynthesis. The minerals or nutrients supplied by fertilizer provide the ingredients needed for photosynthesis and growth. When minerals are lacking or absent in the soil, fertilizer can be added to maintain an adequate supply.
Fertilizer should not be considered a cure for ailing plants when unadapted or unhealthy plants are chosen, carelessly planted or improperly watered.
When fertilizing trees and shrubs, keep these two points in mind: (1) Fertilizer is beneficial when it is needed; but (2) Use it in the right amount, at the right time and in the right place.
Establish a Need for Fertilizing
Consider the following conditions to help you decide if you should fertilize your trees and shrubs:
Soil Test: Have your soil tested through the Clemson Extension Service. A soil test determines the acidity or alkalinity (pH) of the soil, along with the levels of nutrients that are present. Depending on the results, you may need to add nutrients to make up for any deficiencies in the soil. For more information on soil testing refer to the fact sheet HGIC 1652, Soil Testing.
Growth: Look at shrubs and trees for signs of poor growth: poorly colored leaves (pale green to yellow); leaf size smaller than normal; earlier than normal fall coloring and leaf drop; little annual twig growth; or twig or branch dieback. These symptoms of poor growth are not always related to low levels of nutrients in the soil, nor should you assume that fertilizers would cure these problems. Heavily compacted soil; stresses induced by insects, diseases and weeds; or adverse weather conditions can cause these symptoms. Before fertilizing, determine the cause of the problem and correct it.
Planting Age: Fertilizer applications in the early years of established, transplanted trees and shrubs can speed up top growth and help young trees fill their allotted space in the landscape. Slow-release fertilizers are well-suited for recently planted trees and shrubs.
Location: If shrubs or trees are growing in a lawn that is regularly fertilized, there is no need to fertilize them separately. The roots of trees and shrubs will absorb some of the fertilizer applied to the lawn. However, trees and shrubs growing in planting beds may need to be fertilized, especially on sandy soils with little or no organic matter.
Commonly Applied Nutrients
The most commonly applied nutrients are nitrogen (N), phosphorus (P) and potassium (K). Other plant-essential nutrients used in fairly large quantities are calcium, magnesium and sulfur. It is usually unnecessary to apply magnesium and sulfur because they are generally sufficient in South Carolina soils.
Micronutrients such as zinc or iron are added to many fertilizers. If your shrub or tree has a micronutrient deficiency, either apply the recommended rate of the deficient nutrient or use a fertilizer containing the micronutrient that is deficient in the soil.
Kind of Fertilizer to Use
A complete fertilizer, such as 16-4-8, 12-6-6 or 12-4-8, is generally recommended, unless the soil test reveals that phosphorus and potassium are adequate.
Two kinds of fertilizers are available: fast-release and slow-release. Fast-release or water-soluble fertilizers are less expensive than slow-release products, which release nitrogen over an extended period; however, the nutrients in a fast-release fertilizer may leach quickly through the soil. In sandy, well-drained soils, the soluble fertilizer may move past the root system after only a few inches of rainfall or irrigation. In fine-textured clay soils, leaching will be slower, but runoff may be greater.
Slow- or controlled-release fertilizers have extended release periods compared to fast-release fertilizers whose nitrogen is water-soluble and readily available to the plants. The nitrogen in slow-release fertilizers may be sulfur-coated or a form such as IBDU or urea-formaldehyde. One-half or more of the total amount of nitrogen in controlled-release fertilizers should be “water insoluble” or slow-release nitrogen. For newly planted shrubs and trees, or in areas where the potential for runoff is very high, such as slopes or compacted soil, slow-release fertilizers are a good choice. Since the nutrients are released slowly, the potential for fertilizer damage (“burning”) and water contamination is less.
Natural fertilizers, like composted sewage sludge, cow manure or complete fertilizer blends, provide nitrogen and other nutrients slowly. An advantage of these natural “nutrient suppliers” is that they provide minor nutrients – minerals required in small amounts such as iron or zinc – not usually found in synthetic fertilizers. Natural fertilizers also improve the soil structure.
A disadvantage of natural fertilizers is that usually the concentration of nitrogen, phosphorus and potassium are lower. Therefore, a greater amount of a natural fertilizer must be applied to provide the same amount of nutrients that can be obtained with a lesser quantity from a synthetic nutrient source.
Many fertilizers are formulated for use on lawn grasses. Some, known as “weed-and-feed” fertilizers, may contain a herbicide that can damage groundcovers, vines, shrubs and trees. Read the labels and carefully follow the directions.
Amount of Fertilizer to Apply
Similar to lawn fertilizer applications (HGIC 1201, Fertilizing Lawns), the recommended rates for fertilizing shrubs and trees are based on actual pounds of nitrogen. Shrubs and trees can receive 2 to 4 pounds of actual nitrogen per 1,000 square feet of root spread area per year. The root spread area occupies 1½ times the area of the crown spread (3.14 x radius²; see Figure 1). Generally, younger shrubs and trees should receive higher rates of nitrogen than mature plants.
For shrubs and trees in lawns, follow the fertilizer recommendation rate and timing for the turfgrass. Depending on the formulation, applications exceeding 2 pounds of actual nitrogen can overstimulate or burn the grass. If trees or shrubs growing in fertilized lawns show nutrient-deficiency symptoms indicating a need for additional fertilizer, space the fertilizer applications a few months apart, not exceeding the total yearly amount of nitrogen required by your lawn grass (follow the rate and timing for the lawn grass).
Avoid adding too much fertilizer which can harm the plant and the environment. Excessive fertilizer produces rank, weak growth that breaks easily and is susceptible to injury from cold, drought and pests. Also, fertilizer not absorbed by the plant roots may contaminate groundwater and surface water.
Fertilizer Application Methods
Plants may be fertilized by either indirect or direct methods. With either method, apply the fertilizer to the entire root zone area. Because of the naturally high oxygen concentrations near the soil surface, a plant’s principal feeding roots are usually within the top 10 to 14 inches of soil. Many roots of mulched plants are located just beneath the mulch on the soil surface. Apply fertilizer to the surface of the soil or mulch; rainfall or irrigation water will carry it to the roots.
Whatever fertilizer or method of application you choose, irrigate soon after you apply fertilizers to wash any fertilizer from the leaves and to help nutrients dissolve and penetrate through the mulch and soil to the roots. Without irrigation or rainfall, some of the nitrogen applied may evaporate and be lost to the atmosphere without benefiting the plants.
Indirect Fertilization: Shrubs and trees growing in lawns are fertilized indirectly when the lawn is fertilized.
Direct Fertilization: The cheapest and most effective method of directly fertilizing trees and shrubs is broadcasting. Using a cyclone or drop-type spreader, scatter a prescribed amount of fertilizer over the entire root zone area. To obtain the best coverage, split the total amount of fertilizer to be applied in half. Apply one-half of the total amount in one direction and the other half in a direction perpendicular to the first for excellent coverage. When fertilizing over the top of shrubs and groundcovers, make certain the leaves are dry and use a leaf rake or broom to brush fertilizer off the leaves and onto the ground after application. Some plants, like liriope and azaleas, can collect fertilizer granules in the whorls of their leaves and injury may result.
If the soil in a lawn is compacted, aerate the soil, then fertilize. Watering the fertilizer in afterwards will reduce the chances for injuring any groundcover or lawn grasses.
Fertilizer can be applied in liquid form to the leaves of shrubs and trees. Liquid application is commonly used to correct micronutrient deficiencies such as iron chlorosis or yellowing in azaleas (the youngest leaves are yellow leaves with green veins). Foliar applications provide a temporary solution that controls deficiencies in existing leaves with best results achieved in the spring. However, applying fertilizer to the leaves will not cure the real reason for the micronutrient deficiency, which can be the result of an improper soil pH. To find the underlying problem, refer to the soil test. If the pH will not be cor-rected, then the foliar application will have to be repeated.
A liquid or dissolved dry formulation of fertilizer can also be applied in the irrigation water. This practice will place nutrients in the upper soil surface where most of the absorbing roots are located. Use care to get even coverage and the proper dilution rate. A backflow preventer should be installed on the irrigation system.
When to Apply
Apply fertilizer when plants need it and when they can readily absorb the nutrients with their roots. Time your application to coincide with active root growth and adequate soil moisture. Trees and shrubs should be fertilized in early spring, and a light fertilizer application can be made in early summer if conditions are conducive to plant growth (that is, reasonable temperatures and soil moisture). Avoid fertilizing trees and shrubs stressed by drought during the summer months. If water is unavailable, do not fertilize at all because plants will be unable to absorb the nutrients.
For shrubs and trees in lawns, apply the fertilizer at the appropriate time and rate for the turfgrass. Always be sure that adequate moisture (supplied by either rainfall or irrigation) is available.
For fertilizer instructions for new plantings of shrubs and trees, see the fact sheets HGIC 1052, Planting Shrubs Correctly, and HGIC 1001, Planting Trees.
Calculating Area and Fertilizer
Shrubs and trees growing in lawns should be fertilized at the appropriate time and rate for the turfgrass (see Amount of Fertilizer to Apply section). When trees and shrubs are growing in beds or natural areas, you need to calculate the amount of fertilizer needed.
Trees: Apply the fertilizer to the area occupied by the tree’s roots or root zone area. The root zone area is roughly a circular area with the tree in the center. The root zone area extends beyond the drip line or outermost branches of the tree with the roots extending 1½ times the distance from the trunk to the drip line or outermost branches (see Figure 1). For example, if the distance from the trunk of your tree to the drip line, which is called the crown radius, is 8 feet, the “feeder” or mineral-absorbing roots can extend an additional 4 feet beyond the drip line. So, the root zone area can occupy an area up to 12 feet away from the trunk.
Tree cultivars that have a narrow canopy, such as Fastigiata English oak (Quercus robur ‘Fastigiata’) or columnar Japanese pagoda tree (Sophora japonica ‘Columnaris’), or trees with small canopies, or trees that were pruned into unusual shapes, have a root zone area that can be much more than the drip line. In these cases, make your fertilizer calculation based on the trunk diameter. Measure the diameter in inches at 4.5feet above the soil level (dbh) and multiply it by either 1 or 1.5 to get a number expressed in feet. This number will be used as the radius measurement for the fertilization area. For example, the radius of the fertilization area of a 12 inch diameter tree would be 12 to 18 feet, depending on the multiplication factor that was used.
Figure 1. Apply fertilizer evenly on mulched and unmulched surfaces out to about 1½ times the crown radius.
Follow these steps to determine the amount of fertilizer needed to supply 2 pounds of nitrogen per 1,000 ft²:
- Calculate the root zone area (assuming it occupies a roughly circular shape), using the following formula where Pi = 3.14:
Pi x (radius)² = 3.14 x (root zone radius) x (root zone radius)
In the example given above, the root zone area would be:
3.14 x 12 x 12 = 452.16 square feet
- To calculate the amount of fertilizer required per 1,000 square feet, use the following equation:
Lbs N desired x 100%
%N in bag |
= |
Number of pounds of fertilizer required per 1000 square feet in order to apply the desired amount of actual nitrogen |
To deliver 2 pounds of actual nitrogen per 1000 square feet, the equation would look like this:
2 Lbs N x 100%
%N in bag |
= |
Number of pounds of fertilizer required per 1000 square feet in order to apply 2 pounds of actual nitrogen |
Assuming you have a 16-4-8 fertilizer, the equation for this example would look like this:
2 Lbs N x 100%
16% N |
= |
12.5 pounds of 16-4-8 required per 1000 square feet |
- Calculate the actual amount of fertilizer to apply using the following equation:
Root area ft²
1000 ft² |
x |
Pounds fertilizer per 1000 ft² |
= |
fertilizer to apply over root area |
In our example, calculate the amount of 16-4-8 fertilizer required in order to apply 2 pounds of actual nitrogen to 452 square feet:
452 ft²
1000 ft² |
x |
12.5 pounds fertilizer per 1000 ft² |
= |
5.65 lbs fertilizer to apply over root area |
Apply 5.65 pounds (about 11 to 12 cups; 2 cups of 16-4-8 is equivalent to 1 pound) of 16-4-8 evenly over the root zone area. Since most of a tree’s roots can be found in the top foot of soil, broadcast the fertilizer evenly with a rotary or drop-type spreader over the root zone area to fertilize the tree. Water after application to make the nutrients available to the roots. If the tree’s root zone area is confined by a sidewalk or driveway, reduce the root zone area accordingly.
Shrubs: When fertilizing individual shrubs, follow the directions given above for trees. When several shrubs are grouped together in a bed or natural area, however, it is easier to measure the entire area to determine how much fertilizer to apply. Measure the area of the entire bed, making an allowance for the roots that extend beyond the branches of the outermost shrubs. To determine the bed area, use this formula:
Length x width = root zone area
Let’s assume the bed is 30 feet long and 10 feet wide. The bed (root zone) area is 300 square feet.
Calculate the amount of fertilizer required to apply 2 pounds of nitrogen per 1,000 square feet using the same equations from the tree section. Assuming you have a 16-4-8 fertilizer, the first equation would look like this:
2 Lbs N x 100%
16% N |
= |
12.5 pounds of 16-4-8 required per 1000 square feet |
Since the root zone area is 300 square feet, the actual amount of 16-4-8 fertilizer to apply is calculated as follows:
300 ft²
1000 ft² |
x |
12.5 lbs fertilizer per 1000 ft² |
= |
3.75 lbs fertilizer to apply over root area |
Apply 3.75 pounds (about 7 or 8 cups) of 16-4-8 evenly over the mulched bed. Sweep fertilizer off the branches and water afterwards to make the nutrients available to the roots. If the shrub’s root zone area is confined by a sidewalk or driveway, reduce the root zone area accordingly.
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