When to Fertilize Your Lawn in Delaware

Delaware’s classic, four-season climate makes it hard for many of us to figure out lawn management. Worry not. All you have to do is master the most crucial routine – fertilization. Learning when to fertilize your Delaware lawn and using the right kind of product will help you create a strong, healthy, and lush green lawn. 

The traditional approach is to combine fertilization with other lawn care tasks, such as raking, aeration, mowing, weeding, etc., in the springtime. But this practice isn’t ideal for Delaware lawns. Fall is the right time to fertilize your lawn here so it has all the nutrition it needs for the winter and grows generously the following spring. 

In this article, we will learn about fertilization in depth:

Why Timing is Important

No matter what kind of plants you’re feeding, scheduling the correct timing will set them for success or failure in the coming season. The right time to fertilize your lawn depends on many factors, including the climate, light exposure, soil type and pH, plant types in your lawn, and more. 

A good practice for most lawns is to fertilize at least twice a year to ensure good overall health. To be safe, you can remember this rule of thumb: Apply lawn fertilizer when the grass is actively growing. For Delaware lawns with cool-season grasses, this time is early fall or early spring, when the temperatures are still a bit chilly. 

Applying fertilizer in the wrong season can encourage tender new growth that easily gets damaged, encourages weed growth, or simply burns your lawngrass. Early leaf development will simply give you a vulnerable lawn. A few general rules to keep in mind:

  • Always follow the manufacturer’s instructions about application methods and recommended rates.
  • Always perform a soil test before selecting fertilizers.
  • Never fertilize plants until they have fully established. It makes the plant leggy and weak.
  • Try to fertilize outdoor plants and turfgrass in the coolest part of the day. 

The Four R’s of Fertilization

A person fertilizing his/ her lawn

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Knowing the right time to fertilize isn’t enough. There are 4 R’s of nutrient stewardship that should guide fertilizer application for any lawn, advocated by many agricultural conservationists. 

  • Right Source: This involves testing the soil to assess the health of your lawn and then figuring out what it lacks. Selecting the right source could mean choosing an organic fertilizer (manure or compose), dry or liquid form, controlled-release fertilizer, or a product that delivers multiple nutrients. It’s an important step that may save you from overfeeding and burning your lawn. 
  • Right Rate: Fertilizers and soil amendments should be applied at the right rate to balance the nutrients for optimal growth. Some fertilizers, for example organic ones derived from manure, usually need a higher application rate to get to the required level of nutrients. Read more about the right rate of fertilizer application here
  • Right Time: Fertilizer application at the right time is essential to ensure the nutrients are absorbed into the soil. Applying to saturated or frozen ground or right before rain increases the rate of runoff. That’s why fertilizer is generally best applied right before the period of active, increased growth.
  • Right Place: You need to ensure you apply fertilizer in the right areas of the lawn. This means applying fertilizer in the root area and away from driveways, bodies of water, or walkways to prevent spreading the fertilizer to undesired areas. Right placement ensures maximum nutrient efficiency.

Getting all four R’s right fosters a beneficial environment for your plants and wildlife. For fertilizer, remember that more is not always better.

Lawn Fertilization Schedule for Your Delaware Lawn

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Before we get to the monthly lawn fertilization schedule for your Delaware lawn, here are a few pointers to remember.

Nutrient Utilization

Something you need to know before you start is how grass utilizes its nutrients. Lawn grass uses more energy for root growth in the fall and puts energy into growing leaves in the spring.

If you fertilize your lawn when it’s focused on top growth – spring – you basically just push the grass leaves to grow faster and taller, translating into more mowing. On the other hand, fertilizing in the fall promotes a healthy and deep root system that encourages grass to spread by tillers. 

Importance of Nitrogen 

Nitrogen is a major nutrient that contributes to the health of grass plants. It’s a mineral fuels hungry and growing plants. It also boosts chlorophyll production and contributes to a darker, deeper, more emerald-green grass color. 

Nitrogen enters the grass plant through its root system. You can see new shoots appear within hours of nitrogen application. This is why you will likely need to mow more after you apply high-nitrogen fertilizer. 

Nitrogen gives strength to the roots and supports strong shoot growth and makes up a major portion of most types of fertilizers. 

Lawn Fertilization Timeline

Most lawns need to be fed twice a year – once in early spring and once in the fall. The same goes for lawns in Delaware. But, lawn care experts recommend applying 65 to 75% of the total amount of nitrogen fertilizer your lawn needs between September and November

Here’s a timeline that can help keep track of what your lawn eats:

  • Between March and May, apply fertilizer for a nice nutrient boost as your lawn enters the new growing season. Follow-up with a second application in late April or May. 
  • Between June and August give your lawn another light round of fertilizer in the summer to strengthen the grass and help it power through summer stress. 
  • Between late August and early October apply 20 pounds of 10-10-10 fertilizer or two pounds per 1,000 square feet of actual nitrogen to your lawn once in the fall. This goes for homeowners who use a fertilizer that contains at least 35% slowly available nitrogen. 
  • If you’re using a quick-release fertilizer, your first fertilizer application should be  between late August and September. Apply one pound of nitrogen per 1,000 square feet. The second application should be around mid to late fall, or between October and November. We recommend splitting the application for quick-release fertilizers to make sure the plants take up the fertilizer optimally and prevent nitrogen from seeping into our water system. 
  • If you love to see your lawn green up early in the spring, you can apply a mini dose of fertilizer in late October or early November

Suitable Fertilizer Types for Delaware Soils

Your lawn needs three major nutrients. These are:

  • Nitrogen (N): For a deep green color and top growth.
  • Phosphorus (P): For strong root production and spread.
  • Potassium (K): For regulating turf grass chemistry.

And there are different types of fertilizers that your Delaware lawn may need:

Single-Ingredient Fertilizer

Single-ingredient, as the name suggests, contains only one primary plant nutrient. It targets the specific needs of plants at different developmental stages. It is free from fillers as well – no wood ash, marl, lime, manure, limestone, or other materials. 

So, you can get nitrogen, phosphorus, or potassium fertilizers to treat a single problem or boost a certain quality in your Delaware lawn. For example, if your lawn has winter damage, potassium fertilizer will aid plant growth and healthy recovery. Potassium helps to synthesize proteins and starches and assists with nutrient and water uptake. 

Combination Fertilizer

These fertilizers contain all three nutrients in different percentages. Every combination fertilizer comes with a number/letter code that corresponds to the nutrients inside. You can see N-P-K or nitrogen, phosphorus, and potassium coordinate with their percentage found in the fertilizer. 

For example, a 20-5-10 mixture means the presence of 20% nitrogen, 5% phosphorus, and 10% potassium whereas the remaining percentage includes inert filler that aids in even application. This would be classified as a high-nitrogen fertilizer. 

You can pick from a variety of fertilizer ratios depending on what your lawn soil needs and the type of grass. Commonly Delaware soil works well with 10-10-10, 20-5-10, or 6-6-18 fertilizer mixtures. 

Quick-release or Soluble Fertilizers

This type of fertilizer releases nutrients rapidly into the soil. Typically, quick-release fertilizers are water soluble and show immediate results. 

Typically, you have to apply soluble fertilizers more than once for them to show effect since they dissolve quickly and plants may not take up all the available goodness. 

Your Delaware lawn might need a quick-release fertilizer if you need a quick response. For instance, you’re building a new lawn and want it to green up quickly or you want the top growth to be aggressive enough to block weeds. However, soluble fertilizers aren’t always a good idea because they can encourage too much growth, too fast. 

Slow-release Fertilizers

The most suitable type of fertilizer for Delaware soils is slow-release. These fertilizers discharge all their nutrients slowly and over time, making sure your ground always has nitrogen available for growth. They are water-insoluble and dissolve slowly. 

Slow-release formulas are easier to distribute evenly in the lawn, especially if you’re applying granular variety, and assist in a more paced growth. They are designed to release by weathering, water penetration, or microbial action at a rate that is consistent with the grass’s needs. 

These fertilizers are good for regular maintenance. Typically, only one application of slow-release fertilizer is enough and also proves cost-effective for many homeowners. 

Fertilization Guide for Common Grass Types in Delaware

Grass is classified into two categories based on the climate they are adapted to:

  • Cool-season grasses thrive in colder climates. They grow best in spring and fall when the temperatures are somewhere between 60 and 75 degrees Fahrenheit. 
  • Warm-season grass is adapted to hotter climates and grows best in the summer. They need temperatures around 80 to 90 degrees Fahrenheit for optimal growth. 

Delaware is located in the transition zone and typically favors cool-season grasses including Kentucky Bluegrass, Tall fescue, Bentgrass, and Perennial Ryegrass. These grasses take the majority of the nutrition they need in the fall to prepare for winter and recover from summer stress. Mostly, they just need nitrogen to encourage growth and develop a nice green color. 

The only warm-season grass that can make do in Delaware is Zoysiagrass due to its hardy nature. A closer look at different grass types and their fertilization needs:

Kentucky Bluegrass

This is a fast-growing cool-season grass that comes with unique fertilizer needs. Kentucky bluegrass is pretty prone to fertilizer burns. You need to be careful when, how, and what type of fertilizer you apply to it. 

A general guide for fertilizer application on Kentucky bluegrass lawns in Delaware:

  • Use a rotary-type spreader and apply the fertilizer in two different directions to avoid streaking. Water the fertilizer immediately. 
  • Apply a balanced fertilizer, for example, a 10-10-10, at the appropriate rate in the fall, say September. Kentucky bluegrass typically needs 4 to 6 pounds of nitrogen per 1,000 square feet annually, do not exceed that and plan fertilization accordingly. 
  • Use a partial slow-release, high-nitrogen fertilizer, such as 32-3-8, early in November for strong root development. 
  • In spring, apply a slow-release, balanced fertilizer if you need more color in the yard. Try to use an organic, non-burning product. 
  • Never use a quick-release product since Kentucky bluegrass is very prone to fertilize burns. 

Perennial Ryegrass

This cool-season turfgrass thrives in transition zones. It’s a highly drought-tolerant grass that requires little maintenance. 

  • Perennial ryegrass needs 1 to 5 pounds of nitrogen annually per 1,000 square feet. 
  • Apply some fertilizer in the spring after the grass has greened up and save the majority of it for early fall. 
  • Use a slow-release fertilizer that contains a higher percentage of phosphorus and potassium than nitrogen. Phosphorus and potassium are good for a strong root core and proper growth of ryegrass. Whereas nitrogen demand is naturally met by existing legumes in the lawn. So, less nitrogen content in the fertilizer won’t affect growth or grass color. A 6-20-20 fertilizer is a good choice. 

Tall Fescue 

Tall fescue is a low-maintenance turf choice for lawns and sports fields. Thanks to its deep roots, this grass type is pretty resilient and holds up well to dry conditions. 

  • Use a slow-release formula with ideally a 3-1-2 ratio. Most brands have a combination of slow-release and soluble forms of nitrogen. Opt for a fertilizer with as much nitrogen in slow-release form as possible. 
  • Avoid using hose-end sprayers or dry fertilizers for tall fescues as they don’t apply evenly. 
  • It’s preferable to use an organic, balanced fertilizer. 
  • Apply fertilizer in late fall when the soil temperatures are around 50 degrees to stimulate deep root growth. 
  • Tall fescue needs 3 to 5 pounds of nitrogen per year. 


This perennial, cool-season grass is typically used as a part of a seed mix for golf courses, home lawns, and fields. Bentgrass is a creeping grass that develops fine blades and is considered a high-maintenance grass type. It is susceptible to nutrient deficiencies too. 

  • The best time to fertilize bentgrass is fall and early spring.
  • Use a soluble nitrogen fertilizer that contains balanced amounts of nitrogen, phosphorus, and potassium as bentgrass needs all these nutrient supplements to survive. 
  • Bentgrass needs a total of around 5 pounds of nitrogen per 1,000 square feet, per year. 

Tips for Responsible Fertilization

Photo Credit: Pixnio

Who doesn’t like a green, thick lawn? But you need to consider the impact of your lawn management practices on the environment. This includes water waste, chemical pollution, emissions from the production of synthetic herbicides, and more. 

Several studies and research show that a mindful approach to lawn fertilization can reduce the dangers of climate change. A properly maintained lawn does not require immediate remedies and saves you from using harsh, environmentally-unfriendly products to bring it back to life.

Follow these tips to fertilize your lawn more responsibly and minimize nutrient loss:

  • Opt for slow-release fertilizers to reduce leaching into water bodies and reduce the need for multiple applications.
  • Mow at a height of 2.5 inches or higher and return the clippings. 
  • Never apply fertilizer to drought-stressed or dormant grass. Only fertilize your lawn when it is actively growing. 
  • Clear any fertilizer particles that spill on hard surfaces such as roads, sidewalks, driveways, etc., and use a blower or broom to drop them onto the turf. 
  • Consider using organic fertilizers to reduce your carbon footprint. 
  • Avoid using high-nitrogen fertilizers as the manufacturing process for one ton of nitrogen typically involves the release of four to six tons of carbon into the atmosphere. 
  • Consider using rotary spreaders instead of drop-type spreaders. They are easier to work with, give more uniform coverage, and are less time-consuming. 

Seems Too Much? Just Call a Pro!

Keeping track of the right time, fertilizer type, ratio, application technique, and quantity can be too much. Don’t worry, our local pros in Delaware are fully qualified and equipped to discuss, advise, and fertilize your lawn for you. 

Main Image Credit: BanksPhotos / Canva Pro / License

About Wikilawn

Wikilawn’s mission is to provide the best resources and information to help you enjoy your outdoor spaces the way you want. Whether you are a DIY, lawn-loving, gardening guru, or someone who wants help in picking a local lawn care professional, we can smooth your path to a beautiful backyard!

About Wikilawn

Wikilawn’s mission is to provide the best resources and information to help you enjoy your outdoor spaces the way you want. Whether you are a DIY, lawn-loving, gardening guru, or someone who wants help in picking a local lawn care professional, we can smooth your path to a beautiful backyard!