I recently added some shrubs close to my lawn because I felt l needed a scenery change. Initially, the shrubs seemed to adapt to the new environment as they were growing new leaves and stems and appeared to thrive. However, soon, the leaves started turning brown, and on close inspection, the roots were thin, while some were rotting.
You shouldn’t fertilize newly planted shrubs because nitrogen suppresses root growth. They need their energy to establish roots, not leaves and stem growth. The shrubs also absorb fertilizer from the lawn. Drought-stressed and newly planted shrubs only need water and mulch.
It is natural to be tempted to add fertilizer when planting shrubs. I thought I was helping the shrubs, but I did more harm. This article will discuss why you shouldn’t fertilize newly planted shrubs, when to do it, and the best fertilizers to use.
What You Should Know About Fertilizing Newly Planted Shrubs
Newly planted shrubs are establishing their root system, and they need all the energy for root development. Before fertilizing shrubs, you need to know what to expect and why it is not a good idea to fertilize shrubs when planting them.
Here is what you should know about fertilizing newly planted shrubs:
1. Know When to Fertilize Your Shrubs
Even though shrubs do not require fertilizer when newly planted, they will need it later. If the soil conditions are ideal, and you water them regularly, the shrubs will grow well for at least a year. After utilizing the soil nutrients for months, the shrub will need additional nutrients to support the new growth.
The best time to fertilize shrubs is when the roots are well established and ready to absorb more nutrients to support more growth. Fertilize shrubs in early spring, as they are ready for accelerated growth after dormancy during winter. The soil also has adequate moisture in spring.
Avoid fertilizing shrubs when you cannot water them, especially during summer. If you have to, only fertilize the shrubs lightly, but ensure you water the shrubs. You also should not fertilize in the fall because the shrubs will be slowing in preparation for winter when plants are dormant.
Here is a video that discusses the best time to fertilize shrubs:
2. Determine the Type of Fertilizer to Use
When choosing the type of fertilizer to use, you need to consider what the soil needs. Get a soil test to find out which nutrient is missing so that you can choose the ideal fertilizer for your shrubs. Fertilizers have different concentrations of nitrogen (N), phosphorus (P), and potassium (K).
When choosing the fertilizer to use, it is best to get a complete fertilizer with nitrogen, phosphorus, and potassium. However, go for one with a ratio that meets the soil’s needs and the shrubs’ growth stage.
Nitrogen (N) is essential for lush foliage growth. However, fertilizers that contain nitrogen inhibit root growth. If you feel like you need to fertilize your newly planted shrubs, go for a fertilizer with less nitrogen content.
Phosphorus (P) helps with root development and helps with seed and fruit production. It helps perennial shrubs develop hardiness and resistance to harsh environmental conditions.
Potassium (K) stimulates optimal shrub growth. It also aids with flower blooms and fruiting. Shrubs are also more disease resistant and can withstand freezing temperatures because of potassium.
There are three types of fertilizers you can consider for your shrubs:
Fast-release fertilizers are also known as water-soluble fertilizers. These fertilizers leach into the soil quickly. When you use fast-release fertilizer, the shrubs will show sudden growth of shoots, and the will also be greener within a very short time.
There are instances when fast-release fertilizers are ideal. One example is when you want to push growth to stop weeds from interfering with your shrubs.
However, fast-release fertilizers introduce high concentrations of nitrogen, which encourage shoot growth while inhibiting root development.
Slow-release fertilizer is the opposite of fast-release fertilizer. It is insoluble, so shrubs absorb it slowly over a long period. The advantage is that the shrubs utilize the nutrients when in need, so it will be a long time before you need to fertilize again.
You can also use natural fertilizer if you have compost. This is a great option if you prefer an organic solution for your shrubs. However, you will need to apply plenty because natural fertilizer has low nitrogen, potassium, and phosphorus concentrations.
Despite the drawbacks, natural fertilizers contain traces of iron and zinc, which are lacking in fast-release and slow-release fertilizers.
Below, you will find the list of pros and cons of using each type of fertilizer to help you decide which one suits your shrubs best:
3. Observe When Your Shrubs Need Fertilizer
Shrubs can do well in poor soil or soil with decomposing matter when newly planted. Newly planted shrubs only need water and mulch to thrive in the first year of growth.
Avoid applying mulch around the trunk. Instead, add the mulch (shredded bark or wood chips) to the soil when planting the shrubs. For some shrubs, after a few months of watering and mulching, you will need to use fertilizer.
Meanwhile, it is best not to fertilize drought-stressed shrubs because they need to recover first. Ideally, you should give newly planted shrubs at least a year before fertilizing. This allows the roots to develop sufficiently to support the growth of extra foliage.
Although you can decide when to add fertilizer based on your preference, you also have to consider the location of your shrubs. If you plant them adjacent to your lawn, they will absorb the nutrients you use on your turf. Adding more nutrients to the shrubs will result in overfertilization.
The shrubs can also show you that it is time to add fertilizers through the following signs:
- Slow or stunted growth
- Smaller leaves than the normal expected size
- Poor blooming.
It is sometimes easy to miss the telltale signs that your shrubs need fertilizer. However, if you are keen, you will not miss the signs, and you can go ahead and fertilize the soil. Once the shrubs develop strong roots, they are ready to take in fertilizer to support the growth of the shrubs.
It is important to remember that before applying fertilizer, you need to establish a need for it.
Test the soil pH. Most shrubs thrive when the soil pH is 6.2-6.8. Some shrubs, like azaleas (Rhododendron spp.), prefer soil with a pH of 4.5-6.0. Stunted growth may also be a sign the shrubs need extra nutrients.
The Ross Tree & Shrub Fertilizer on Amazon.com has a nutrient ratio of 25:10:10. It is easy to use, and it boosts root fertility. For faster application, it is best to use a root feeder.
4. Determine How Much Fertilizer Your Shrubs Need
Once you identify a need to fertilize your shrub, you will need to determine how much fertilizer to use. When you use too much fertilizer, expect impaired growth, brown leaf margins, defoliation, and root discoloration.
Over-fertilization can affect the long-term health of the shrubs, while under-fertilization will deny the shrubs important nutrients needed for growth.
How much fertilizer your shrub needs will depend on its age, root area, and nitrogen needs. Younger shrubs need more nitrogen than older shrubs. Most shrubs absorb 2-4 pounds (0.9-1.8 kg) of fertilizer per 1,000 square feet (93 sq. m.) of root spread yearly.
Most manufacturers recommend the amount of shrub fertilizer to use according to root spread. The best way to calculate root spread is to look at the foliage spread.
The root spread is approximately 1.5 times the size of the foliage spread. For example, if the foliage spread is 3 feet (0.9 m), the root spread is 4.5 feet (1.4 m).
5. Know How to Apply Fertilizer on Shrubs
In the first year of newly planted shrubs, the change in foliage will not be much since the shrub would have spent the year adjusting to the new environment and establishing the roots.
When you start applying fertilizer, you will need to decide if you will be doing it through the soil or on the foliage.
You can apply fertilizer using the following methods:
- Inject liquid fertilizer into the soil: Drill some holes around the shrub. Ensure the injection sites are at least 2-3 feet (61-91.4 cm) apart. Inject the fertilizer 15-18 inches (38.1-45.7 cm) deep. This method also helps with soil aeration.
- Spray liquid fertilizer on the foliage: This method is ideal when the shrub is in active growth. It quickly corrects nutrient deficiencies in shrubs and encourages normal bud growth in shoots.
- Apply fertilizer granules around the base of the shrubs: These are slow-release fertilizers. The shrubs will feed on the nutrients slowly, according to need.
You can use a deep root irrigation wand to apply liquid fertilizer deep into the roots of the shrubs. It delivers fertilizer directly to the root, so there is no risk of a runoff.
Shrubs are delicate in the first year you plant them. Avoid planting shrubs in a place where they are likely to absorb fertilizer from other plants or your lawn. If necessary, use very little fertilizer in the area close to the shrubs in the first year.
When you start fertilizing your shrubs, schedule to fertilize your lawn and shrubs simultaneously. This way, the shrub gets a break and doesn’t suffer from overfertilization all year long.