by Joshua Criss | Mar 6, 2025
Ah, springtime is approaching quickly. You and I both know you’re getting anxious to get out into your gardens to grow your plants. I’m not faulting you, far from it. You’ll find that your local Extension agents want your garden to succeed as much as you do. Because we all want you to have a bountiful harvest, we need to have a conversation about fertility in your lawns and gardens.
Definitions
Before we get too deep into this topic, let’s define nutrition. You may hear some refer to fertilizers as “plant food.” While this is a common phrase concerning fertilizers, it is not factually accurate. Food is associated with energy creation within an organism. Plants are autotrophs, meaning they convert sunlight into energy. So, under this premise, sunlight is plant food, whereas plant nutrition is the building blocks of tissues or catalysts of metabolic processes.
The 17 elements designated as plant essential nutrients are categorized based on the quantity needed for healthy growth. All are important to have in your soil; as per the “Law of the Minimum,” your plant’s development will be limited based on the most deficient element.
UF/IFAS Photo
Macros
Those elements with the largest demand within the plant are known as macronutrients. The three most critical of these are very often absent in fertilizer conversations as they cannot be added to soil in granule form. These are carbon, hydrogen, and oxygen, and their presence in your garden results from your cultural practices. You get them from air and water in the pore spaces of your soil. Appropriate tillage and irrigation are the only ways to provide these elements to your plants. They are critical for proper photosynthesis and fluid balance in the plant.
The most discussed elements are so vital that they make up the three numbers on every bag of fertilizer. These are nitrogen (N), phosphorous (P), and potassium (K), all of which may be added to soil to overcome deficiencies (N often being the limiting factor). These elements are crucial for protein creation, photosynthesis, and fluid movement.
Secondary Nutrition
UF/IFAS Photo: J. Criss
The next set of nutrients have less demand than NPK. They are sulfur (S), magnesium (Mg), and calcium (Ca). Ca is essential for cell structure but is often abundant in our soils. S is frequently rained out of the atmosphere (though you may still need to add some) and facilitates enzymatic processes in plant cells. Mg needs the most attention in this category as it has a lot of mythology among gardeners. You’ve likely heard you should add this element to “green up” your plants. While it is true that Mg is critical to chlorophyll, adding it without testing for deficiencies first is a recipe for poor plant growth.
Micros
Our final category of fertilizer is micronutrients. These are iron (Fe), manganese (Mn), boron (B), chlorine (Cl), zinc (Z), copper (Cu), molybdenum (Mo), and nickel (Ni). These serve various functions in the plant, mainly in metabolic processes.
To Sum Up
Plant fertilization is critical for lawns and gardens. It behooves gardeners to understand these elements and their role in plant growth. Once you do, you’ll understand the importance of applying the correct version of the element in the proper amount at a time and location to maximize use efficiency. You can learn more about what they do and how they react in the soil here. For more information, contact your local extension office.
by Joshua Criss | Jan 9, 2025
Well folks, the earth has made yet another trip around the sun, and we find ourselves in another of hopefully many a new year. The weather has been cold, but it’s important that we spend a few moments plotting a strategy for our lawns in the coming year. Lawncare is a subject which is shrouded in myths and often misunderstood. Luckily, a little bit of knowledge can help you achieve stress free healthy turfgrasses.
Lifecycle
The first thing homeowners should understand is how turfgrass grows throughout the year. Turfgrass is split into warm and cool season species. You may have guessed that in the Florida Panhandle, warm season grasses are dominant. These grasses perform well in warmer weather going dormant when temperature begins to fall. During this dormant period, these grasses turn brown and may appear to have died. The grass itself is alive and well, but the roots have died back significantly.
Fertilizers
Why is this an important piece of information? There is no point in applying fertilizers to turfgrasses with no ability to absorb them. Instead, waiting until mid-April (think Tax Day) for fertilizers provides two key benefits. First, it allows time for the grass to develop a thick mat of roots. As roots are the main tissue for nutrient entry into plants allowing your lawn to utilize the applied nutrition. Second, waiting until a little later evades late season freezes. Cold weather may harm early season growth which stresses your lawn which could cause die back allowing weeds to take over.
UF/IFAS photo: GI-BMP
Weed Prevention
The subject of weeds brings us to a critical cultural practice in terms of lawncare. The application of preemergent herbicides. These herbicides are designed to create a barrier in the top 1/2 inch of soil which prevents shoot and root growth after weed seed germination.
Now, it’s important to understand, there are hundreds of thousands of weed seeds in the top layers of soil all over the world. Weeds take advantage of open spots in your lawn as does any plant in any ecological system.
A preemergent herbicide prevents weed from being able to fill those spaces, by preventing their growth. Given the proper watering and fertilization, your grass may now fill these voids. Your lawn will outcompete the weeds and become its own preventative.
Selecting and application of a pre-emergent herbicide does have some nuance. Not every product is compatible with every grass type, consult our Weed Management Guide to select a product that will work for your lawn. Another concern is application timing and frequency. Multiple applications will likely be required in the spring due to those triggers which break seed dormancy combined with product efficacy timelines. Local extension offices are a great resource for specificity, but generally application will need to be mid-February with a second application 6-8 weeks later based on the product label. Also important to note is that this is a long-term process. It may take a few years of spring and fall application to eradicate the weeds in your lawn.
Lawn decline from weed infestation UF/IFAS Photo: Pawel Petelewicz
To Sum Up
Turfgrasses make excellent groundcovers and are look best when grown as stress free as possible. In the early parts of the year that entails holding off on fertilization and adding a layer of protection for summer weeds. Getting to know your turfgrass and familiarizing yourself with proper cultural practices will go a long way to making a healthy lush lawn. For more information you may read through our Florida Lawn Handbook or consult your local Extension Agent.
by Joshua Criss | Nov 21, 2024
A Sea of Yellow
You do not often see a sea of yellow flowers on what was recently a field of row crops in North Florida. In this instance, the culprit is a cover crop called sunn hemp (Crotalaria juncea). Cover cropping, or green manure as it is sometimes known, is not a new concept. It is a great method for improving soil quality, adding organic matter, augmenting nitrogen supply, supporting pollinators when resources begin to wane, and combating nematodes. Incorporating this sustainable agriculture practice into home vegetable gardens is an excellent method to build long-term viability and production.
Many plants may be used in this capacity, but this article will focus on sunn hemp. This annual is an herbaceous, short-day flowering plant in the Lamiaceae or legume family. Its erect stems produce a great deal of biomass and, as a legume, will augment nitrogen stores within your soil profile. As if that wasn’t enough to sell you, this plant is also known to suppress nematode populations. Native to India and Pakistan, where sunn hemp is grown for fiber, this plant grows well in tropical and temperate environments. It will thrive in even sub-par conditions and requires little fertilizer input.
UF/IFAS Photo: Josh Criss
Seed Time
Seed this plant once your summer gardens have begun to wane. The shorter day length will keep the plant confined to about 3-4 feet while still allowing it to flower. It may also be planted earlier in the year to maximize below-ground biomass and add organic matter. In this scenario, the plant will likely grow to 7 feet tall with a closed canopy within 10 weeks.
Sunn hemp requires little fertilization as it is a legume, a plant family known to fix nitrogen from the atmosphere. This same mechanism is one of the features of this plant as a cover or green manure crop, as it can add up to 320 pounds of nitrogen per acre back to the soil when planted en masse.
Seeding rates within a home garden are much smaller. A farmer may plant 30-50 pounds of seed, which is not practical in small-scale growing. Instead, aim to cover the garden area through broadcasting seed, as a denser planting will reduce the later branching of this plant. Ensure you have 8-12 weeks of warm, frost-free weather, and terminate them prior to reaching the full bloom stage. Doing so will provide your gardens with the same benefits seen in farm fields utilizing this sustainable practice.
UF/IFAS Photo: Josh Criss
To Sum it Up
Sunn hemp is an excellent plant for your gardens before your fall greens. The biomass it produces and the nitrogen it recovers make it very attractive to farmers and should raise eyebrows even in the home garden. The trick is learning to manage this plant within your crop rotation. For more information on soil management refer to these IFAS documents, or contact your local extension agent for additional information on this and any topic regarding your gardens and more.
by Joshua Criss | Oct 4, 2024
Winter color is not always easy to find here in Florida. While staple annuals such as snapdragons (Antirrhinum majus) require planning and extra effort in the autumn. Instead, envision a perennial powerhouse that will not only provide colorful berries when the temperature drops but is a pollinator magnet in the spring. The Holly tree (Ilex spp.) perfectly embodies this vision. These low-maintenance evergreens, with their waxy leaves and colorful berries, are a sight to behold in your landscape, whether as a hedge or an accent plant.
Where and How to Plant
Hollies generally prefer partial shade and well-drained soils. However, exceptions exist, such as the Dahoon holly (Ilex cassine), adapted to wetter environments. Whatever cultivar you place in your landscape, following the planting and care instructions is crucial. Plant it in a hole approximately one foot wider than the root ball. Dig deep enough to cover most of the root ball but shallow enough so the uppermost root is slightly above the soil line. This may be counterintuitive, but roots need air to thrive, and shallow planting allows infiltration in the rhizosphere. To regulate soil temperature and soil moisture, add a 2-3 inch layer of mulch around the base of the plant. It is critical to leave some space between the tree trunk and mulch.
Photo: Edward Gilman, UF/IFAS.
Cultural Practices for Success
Irrigation is critical to establishing these plants, which should take between 3 and 6 months. Once established, cease irrigation except in drought conditions. Don’t apply too much water in either case, as hollies will suffer with wet feet. Fertilizers should be applied twice yearly in March and September. Have your soil tested before applying fertilizer to ensure a complete nutrient profile.
Pruning is not routinely required with holly trees. It is advisable to remove dead, diseased, and dysfunctional branches. Dysfunctional branches are those that grow back toward the main leader of the tree. These risk rubbing against one another, causing wounds that may become infiltration sites for pathogens. You should also remove sprouts coming from the root zone, commonly called suckers.
Potential Issues
Pests and pathogens are infrequent in hollies and are usually the product of improper growing practices. Occasionally, scale or spittlebug insects can infest the tree. Their presence will be punctuated by the appearance of blackened leaves, which is a symptom of sooty mold. Scouting these plants often will allow early detection and control of these pests. Some pathogens may also affect these trees. Most often, these are fungi caused by excessive moisture. Look for dieback or strange growth patterns in the plant’s foliage. When you see these, make sure the roots are not waterlogged.
Photo: UF/IFAS
Summing Things Up
Hollies are an excellent and low maintenance addition to any landscape. Their berries and flowering patterns provide multiple seasons of interest and are a resource for birds and pollinators alike. For more information on Florida wildflowers, see these Ask IFAS documents, or contact your local extension agent for additional information on this and any topic regarding your gardens and more.
by Joshua Criss | Aug 12, 2024
Managing your soil is easily the most critical task in gardening. Well-managed soils retain water and nutrients, making them available to your plants, thus enabling them to thrive. It may seem daunting, but with a bit of knowledge, you’ll quickly discover that soil management is much simpler than you thought. Soil management can be broken down into two major topics. The first is the physical properties outlined in a previous article, which may be found here. The second, and arguably more complicated of the two, are those chemical properties that drive plant growth.
The What and Why of Soil pH
When considering chemical properties, you first need to look at soil pH. This is the measure of acidity or alkalinity within your soil profile. Innate soil pH is a product of the parent material from which your soil has formed, which tends to be slightly acidic on the Panhandle. Testing is the only accurate way to measure your soil’s pH level and buffering capacity. Your county extension office will be happy to facilitate that testing.
So, why is pH so important to plant growth? You’ll want to manage your soil’s pH for two reasons. The first is that soil acidity greatly influences the form that fertilizers and herbicides take in your landscape. Put into context, if you add fertilizers into the soil with an incorrect pH, that fertilizer may not dissolve in the water present. It will thus be unavailable to your plants. Here is another example of putting the right plant in the right place. Some, such as centipedegrass, thrive in a low-nutrition environment created by a low pH, whereas most vegetable plant species and many other landscape species only want a slightly acidic environment. Placing plants that will grow in the natural pH of your soil is a great way to ensure success in your gardens.
UF/IFAS photo
Ok, you’ve tested your soil and discovered it is not optimal for the plants you want to grow. Fear not, as you can take some actions to adjust your soil’s inherent acidity levels. Keep in mind that any changes will be very localized and are temporary. To raise soil pH, you must apply some version of calcium, colloquially called liming. Your calcium source should be based on soil testing, as different types may also add needed nutrients. Most notably, dolomitic lime will change soil pH while adding magnesium. Soil testing will also tell you to provide the buffering capacity of your soil, which will dictate the amount needed to adjust the soil properly. Soil pH may also be lowered through elemental sulfur additions, but this process is very difficult and may become detrimental to plant growth through repeated application. In this instance, it may be preferable to address via plant selection versus pH adjustment.
How Does Soil Hold Onto Water and Nutrition
The other main consideration for soil chemical properties is cation exchange capacity or CEC. Now, this can be a very complicated topic. Put very simply, it refers to your soil’s ability to retain both water and applied nutrients. It’s important to understand as it holds components critical to plant growth in the root zone of said plants. This happens as there are negative charges on the surfaces of clay particles in your soil that latch onto the positive ions of applied fertilizers.
Photo: University of Georgia Extension
So, what about soils low in clay, such as those in Florida? Organic matter will help in this arena. It mimics clay’s properties and will retain nutrients better than your native soil. However, this is not a pass to add endless amounts of compost, as they come with a nutritive load that must be considered in your garden management plan. Adding 1-3 inches worked into your plant root zone is more than enough when establishing new gardens.
Understanding your soil is critical when gardening anywhere. In Florida, where soils are less than optimal, understanding how water and nutrients are retained and used by your plants will help avoid much frustration. For more information on soil management refer to these IFAS documents, or contact your local extension agent for additional information on this and any topic regarding your gardens and more.
