Demystifying Nitrogen

Demystifying Nitrogen

Fertilization is a subject that throws many a gardener for a loop. It can be confusing, and we in the professional horticulture world understand. This topic will almost always be approached from the prospective of nitrogen. So why does nitrogen get so much attention? What is its role in plant growth? Nitrogen is the primary driver of protein synthesis, plant metabolism, energy creation, and is the structural component in chlorophyll. These are all extremely important functions leaving little doubt as to why it’s so critical. Your plants use this resource abundantly for healthy growth. The reason it gets so much attention is owing to its frangibility in the soil. Nitrogen goes through changes once applied to soils and is readily lost to the environment. For this reason, nitrogen application needs to be timed appropriately, and your cultural practices need to be such that encourage plant uptake over losses to the environment. Fear not my friends, this article will bolster your insight into the wonderful world of nitrogen, and have your plants growing strong and healthy.

The What and Why of Nitrogen

Nitrogen is one of three macronutrients identified in every fertilizer bag as the first of three numbers. This standardized NPK labeling refers to the amount of this nutrient in the bag by percentage of total weight. Application rates should be based on this number, and how much nitrogen you’ll need to cover a specified area. which number you use is based on the equipment you have to apply more so than the plant requirements.

Fertilizer bag
UF/IFAS Photo: Dan Culbert

Nitrogen can be natural or man made. Natural sources come in the form of composts, manures, and through atmospheric deposition. The later of these sources means rain, which washes nitrogen out of the atmosphere and into your soils. Man made sources conversely come in bags and are the result of a combustion process developed by Fritz Haber, and Carl Bosch circa 1910. Either way, nitrogen will be in the form of ammonia, nitrate, ammonium, or urea. Knowing this is important as it will dictate application methodologies. For instance, urea applied to the surface will escape into the atmosphere if not incorporated into your garden.

Fertilizer label showing types of nitrogen used.
UF/IFAS photo: T.W. Shaddox

Nitrogen type will also affect soil pH. This is especially important with ammonia-based fertilizers as residual acidity from them may lower pH. Applying the correct type will mitigate large unwanted changes in soil. Why are we concerned with soil pH? It speaks to nutrient availability and, thus how well your plants grow.  It can be overwhelming, but with soil testing and a call to your extension office, it’s easy to identify the appropriate fertilizers for your application.

Reactions in Soils

Soil is often considered inert, holding plants in place while providing a pantry full of the nutrients they crave. Nothing is further from the truth. Soil is a living entity with its own physical and chemical properties. The addition of anything, including irrigation, affects these properties.

Nitrogen takes two forms in your soil aside from nitrogen source. Inorganic nitrogen is converted from soil organic matter in a process known as mineralization or added from bagged fertilizers and is available for plant uptake. Organic nitrogen is unavailable for plant uptake and will be present in the natural forms listed in the previous section. Both are susceptible to the nitrogen cycle and may be lost to the environment. This happens as water passes through soil (leaching), erosion, runoff, or is lost to the atmosphere through volatilization and may have negative effects on surrounding water bodies.

Nitrogen cycle illustration

To mitigate these risks through responsible fertilizer application, irrigation management, and landscape design. Apply fertilizers when plant uptake is favorable, and only to the level required by your plants. This will be during heavy vegetative growth periods such as initial installation. Irrigate as dictated by your plant life vs on a timer. Watering is a vital practice, but often overdone. Keep water levels enough to avoid plant stress but not excessive. Doing so reduces leaching potential and will keep your plants healthier. Finally, design your landscape with Florida Friendly Landscaping principles. Integrate diverse plant life, including turfgrasses and landscaped beds. The goal here is to allow enough plant life to absorb excess storm water, and support local pollinator populations.

Nitrogen is a critical piece of your fertilizer routine. It’s important to understand how it reacts with both your plants and your soils. A little knowledge can go a long way to keeping your plants healthy while mitigating risks from over fertilization. For more information, see this Ask IFAS document, or contact your local extension agent for additional information on this and any topic regarding your gardens and more.

Mix Landscapes to Maximize Impact

Mix Landscapes to Maximize Impact

Landscapes can be a tricky topic. Doubtless, you’ve heard people debate the ecological benefits of a turfgrass lawn. An internet search will have your head swimming in opinion pieces detailing the benefits of keeping and removing your turfgrasses. Some outline the aesthetic virtues while others speak to pollinator support from native flowering plants. It can be overwhelming and there are a lot of factors to weigh in these decisions. Luckily this is a situation in which following the Florida Friendly Landscaping program means you may have your cake and eat it too.

Florida Friendly Landscaping

Florida Friendly Landscaping or FFL is a series of nine principles designed to maximize the ecological services of your landscaping while minimizing inputs. It all begins with selecting the correct plants and placing them in the proper place. Once in place, proper maintenance is covered by the following three principles which involve proper watering, fertilization, and mulching. Since we planted good larval and nectar plants our landscape attracts wildlife, which is the next principle. In this process, you’re likely to also attract insects you don’t want. Managing these responsibly is our next principle. The final three principles involve utilizing plant waste from your landscape, managing stormwater, and protecting waterways. Where a good deal of these involves proper maintenance and selection of plants, the purpose of this article is to highlight the two main ecological services outlined in these principles.

FFL yard sign
UF/IFAS Photo: Tyler Jones.

Support Wildlife

The first of these is attracting wildlife which for a wide swath of homeowners will focus on supporting pollinators. Pollination is critical for non-vegetative reproduction in plants. It’s the reason they produce vegetables or flowers. Many creatures aside from the well known ones perform pollination including bats, birds, flies, and beetles. Look into the needs of the pollinators you wish to attract and understand how these creatures eat, breed, and nest. These pieces of knowledge will help you decide on landscape plants. Create habitat by planting smaller areas with native and noninvasive plants which meet the needs of the pollinators you wish to attract. These areas need not replace all the turfgrass areas, and in fact, it’s better if they don’t. 

flowering garden bed
Photo: Joshua Criss

Turfgrasses are Crucial in Your Landscape

Turfgrasses are ecological workhorses. They cool your environment, build soil, prevent erosion, aid water infiltration, and are arguably the best bio-filter in the plant world. Properly maintaining your grass is much easier than you may think. They need 1/2 to 3/4 inch of water per irrigation event, and generally only 1-2 pounds of nitrogen per 1000 square feet per year (Bermudagrass may need up to 5 pounds). Even this may be less pending soil testing. Keeping these grasses stress free through proper maintenance allows them to grow lush with little input.

Their benefit as a bio-filter comes into play with regard to storm water. This runoff is a seldom thought of as a pollution source. On top of moving debris and latent chemicals into local waterways, it washes dissolved organic nitrogen through the soil. All of this eventually finds its way into local waterways. Grass areas of your landscape slow free flowing storm water and filter pollutants preventing excess nutrient and pollution loads in the watershed.

Turfgrass surrounded by flowering beds
Photo: Joshua Criss

Following the principles of a Florida Friendly Landscape can boost the aesthetics of your property and provide an ecological boon. Mix flowering and turfgrass sections of your landscape to meet these goals. For more information on these principles, see this Ask IFAS document, or contact your local extension agent for additional information on this and any topic regarding your gardens and more.

Blackberries in the Home Landscape

Blackberries in the Home Landscape

The Blackberry

When you think of fruit production in Florida, blackberries (Rubus spp.) will not quickly jump to mind. Many people envision viny plants infiltrating your gardens and attacking you with their tiny spines. These are dewberries and are not known for large or consistent fruit. Though scientifically of the same name, bush varietals are a world apart. Bush blackberries fall into the rosaceae or rose family. They are deciduous fruiting shrubs, generally acclimatized to temperate environments. Luckily for us, they grow in the Panhandle. They’ve not taken off as an agronomic crop large scale due to the brittle nature of their fruit. However, with estimated production rates of 6000lb per acre many parts of the country, their value in home food production is undeniable.

close up of blackberry fruit
UF/IFAS photo: Brent Sellers

Which to Pick

The University of Florida has been heavily breeding blackberries, but as with all gardens, plant selection is vital. The most critical factor in selecting blackberries is the chill hour requirement. You may recall that chill hours are the total time below 45 degrees a plant needs to set fruit the following spring. The vast majority of our area gets 660-700 chill hours per year on average, with the extreme north end getting upwards of 800 hours yearly. Once this is determined, the focus shifts to growth habit. Many grow erect and will not need trellising, but there are cultivars that vine and will need support. A final consideration for cultivar selection is whether or not they will need pollinator plants as an accompaniment. If the berries you want have this need, pick a compatible cultivar with a similar bloom time. Some cultivars that will do well in north Florida include ‘Arapaho,’ ‘Chickasaw,’ and ‘Choctaw.’

Blackberry bush
UF/IFAS photo: Mary Salinas

Planting and Care

Plant blackberries over the winter months much as you would any deciduous fruits. If you must store the plant before planting, keep the roots moist if you will be holding the plant for any amount of time. Ensure the first main root is just above the soil line, and remove any air pockets as you backfill the planting hole. Keep the soil moist but not overly wet, and avoid overhead watering. Space the plants according to their full size, which varies based on cultivar. These have shallow root systems and are therefore not heavy feeders. As a result, apply nutrients in the spring of the year they’re planted at ¼ pound per plant. In subsequent years apply ¼ to ½ a pound per plant twice a year. Irrigation and weed control will also be critical in their first year. Irrigation will become less important once the shrubs establish in their location.

Growing food in your home landscape is a great way to reconnect with your property and bring your food system as local as possible. Blackberries are low-maintenance fruit that, once established will provide years of production with minimal effort. For more information, see this Ask IFAS document. Contact your local extension agent for additional information on this and any other topic regarding your gardens.

Gardening in the Panhandle LIVE! Program Summary: Citrus in the Home Landscape

Gardening in the Panhandle LIVE! Program Summary: Citrus in the Home Landscape

This month’s program focused on Citrus for the Home Landscape. Citrus is a wonderful addition to your landscape. You may have tried it before and run into some issues. This episode of Gardening in the Panhandle seeks to demystify these trees. Below is a summary of the program with links and references.

Panelists introduction:

Daniel Leonard – County Extension Director/Agriculture, Horticulture, and Natural Resources Agent, Calhoun County (Moderator)

Beth Bolles – Horticulture agent, Escambia County

Matt Lollar – Commercial Horticulture agent, Santa Rosa County

Danielle Williams – Regional Commercial Horticulture agent, Gadsden County

  • Danielle was asked what the best cold hearty citrus is in the Panhandle:

She began by describing the conditions brought to the region by winter storm Elliot, and that one tree which performed well during it was Satsuma Mandarin (Citrus unshiu) which tends to be the most cold hearty citrus in our area that will grow. Some of these varieties are Brown Select, Owari, and Zaishan. Another variety of citrus that may be grown here is kumquat (Citrus japonica) and calamondin (Citrus x microcarpa) are other types that typically grow here. At the moment, there is evidence of damage to other types of citrus from the cold. Particularly with lemons, limes, and grapefruit.  

Link: Cold Hearty Citrus –

  • Matt was then asked which limes grow best in N. Florida:

His top two recommendations are limequat (Citrofortunella x floridana) or if you’re interested in more juice or zest, a rangpur lime (Citrus x limona) which is a lemon crossed with a mandarin. They produce heavily and make an excellent key lime pie. They can be propagated from seed and be true to type. However, it was noted that it is illegal in Florida to propagate your own citrus tree and that they must be purchased from a certified citrus nursery.  

Link: Citrus in the home landscape –

  • The next question returned to Matt concerning growing key limes in containers:

There are a number of citrus recommended for containers as they are very adaptable to containers. Key lime (Citrus x aurantiifolia) should do well in containers though you’ll want a large container to accommodate root growth and drainage. The second of these is important as citrus does not like to sit in excessive moisture. Purchase a potting mix (one that does not specify “garden soil”) from the store preferably one without a moisture control element. They will need to be put inside for cold protection and will need supplemental lighting while indoors.  

Link: Growing fruit crops in containers –

  • Beth was asked next about the viability of growing citrus under the canopy of other trees:

She said that citrus needs sunlight to produce well in general, but there is a possibility of growing citrus with a little shade.  They will most likely not do well in excessive shade and if grown in a pine hammock you may need to amend soils. Recent research has shown promise in citrus production and potentially some greening protection under a 30% shaded environment.

Link: Made in the Shade –

  • The panel went back to Danielle about which lemons do well in the Panhandle:

She said that Meyer lemon (Citrus x meyeri) is one of our more cold-tolerant types, but that is not always the case. Harvey lemons (Citrus x pyriformis) may work as well though they may suffer the same as Meyer types.

Link: Meyer lemon –  Meyer Lemon – Gardening Solutions – University of Florida, Institute of Food and Agricultural Sciences (

  • The whole panel was asked to provide some varieties of grapefruit that may do well:

Danielle suggested ruby red grapefruit (Citrus paradisi ‘Ruby Red’) or marsh grapefruit (Citrus paradisi ‘Marsh’) are her favorites that may do well with cold depending on the microclimates where they are grown. Matt agreed with Danielle and added that a pomelo (Citrus maxima) could also be an option though they can get very large fruit and may need extra work to eat. Beth added that she agreed but to keep in mind that these may still suffer in colder years and emphasized microclimates and knowing your growth environment.

  • Matt was asked next about cold mitigation strategies for citrus:

He said you should plant new trees close to your house on the south side or use surrounding trees to create microclimates. Heavily wetting the soil will also provide some protection when cold is expected due to heat absorption with wet soil. You can also pile dirt or mulch around the graft union of the tree which will need to be removed when the cold is gone. He also pointed out that commercial growers often use microjet irrigation throughout the night in freeze which can release some heat.

Link: Citrus cold protection –

  • Beth then answered a question about growing in containers:

She said you may have to accept the frangible nature of citrus. She went on to say you need to match the container to the tree and that will come with a large amount of work. So containers are not worth it in her opinion.

Link: Growing fruit crops in containers –

  • Danielle was asked if the tree will bear fruit from suckers:

All citrus is grafted, and where the scion wood and root stock meet is called a bud union. Above this union is the desired tree capable of producing the anticipated fruit, below is the rootstock that was chosen for its ability to survive and will not necessarily produce good fruit which is most likely this is a sour orange.  The sprouts originating from the rootstock are known as suckers which may present differently than the rest of the trees (leaves in threes, excessive spines).  Growth from above the graft union will be the desired tree capable of producing the desired fruit.

Link: Citrus rootstock –

  • Matt was then asked if Meyer lemon is grafted:

The answer is that there is a high likelihood that your tree was grafted if bought from the nursery. Citrus may be grown from seed but will take a long time to grow and produce fruit.

  • Danielle was then asked about letting citrus grow in a pot prior to planting into the environment and whether this will add cold protection:

She said that you can of course allow the tree to grow in a container prior to planting in your yard, but this is not a requirement. Established trees handle cold weather better than stressed trees which have recently been planted. To this end, make sure you plant the trees in spring or summer prior to August to allow them some growth time in your yard before the cold arrives.

Link: Citrus cold protection –

  • Beth was asked next about post-freeze pruning:

She advised waiting on pruning after a freeze to allow the plant to come back naturally. Once the plant has come back with enough new growth to help it survive. At about 4 months post-freeze event you may begin to assume the plant has died if growth is not beginning. Danielle added that there is a chance the tree will begin to grow again, and the new growth will not survive. This is not unusual, and you should wait to prune till May or June to ensure you’re only removing dead tissue.   

  • Matt next answered a question about cold damage in containerized citrus:

He pointed out that your tree in this situation may be more susceptible to damage as it did not have the surrounding soil as an insulator from the cold.

Link: Post-freeze damage in citrus –

  • The whole panel was asked about replacing a tree in the same spot that has died:

Danielle answered that you should take into account that the tree was in the correct place to begin with and if the reason for death was from the cold or something else.  If from cold there should be no issue with replacing that tree.

  • Danielle was then asked about citrus greening:

Citrus is a major crop in Florida and has been declining due in part to citrus greening. It is a bacteria transmitted by the Asian Citrus Psyllid. This disease plugs up the phloem or nutrient transmission tissue in the tree leading to poor quality fruit and causing decline in tree health. There is a research station dedicated to breeding and dealing with this disease. UF has developed varieties with greening tolerance, and the disease is not as widespread in the Panhandle. ‘Sugarbelle’ and ‘Bingo’ are two of these varieties and are a type of mandarin that did somewhat ok in the cold.  Look for the adult insect in the new growth to monitor tree health along with yellowing, corky veins, and lopsided fruit. The difference between this and nutrient deficiency lies in the leaf which will lose symmetry with the disease. Contact your extension agent to identify the disease.

Link: Selecting Citrus –

  • Beth then addressed when you should plant citrus trees:

She emphasized the need to buy registered citrus trees from a reputable nursery. Pick the correct location and plant spring to summer. The key to citrus is planting depth. They need to be shallow in the soil to allow proper water, nutrients, and air flow.

  • Matt was asked next about fertilization:

He said you can begin fertilization about a month after planting keeping in mind where the root zone of the tree. Trees that are a year old or more will benefit from multiple fertilizations throughout the year approximately 6 times in ¼ to ½ pound increments. The table at the end of the link below will guide you to correct fertilization.

Link: Citrus in the Home Landscape –

  • Danielle then further described fertilization:

For satsuma, the tree requires more fertilizer with age. Anything five years of older needs about 1-1.5 pounds of nitrogen per year, split into multiple applications. Reference the guide from Matt’s answer for the number of applications. The preblended fruit tree fertilizers sold in the store are great for use with citrus trees.  

  • Beth was asked next about mulching:

Many documents don’t recommend mulch due to the disease potential. This is for commercial groves and does not necessarily relate to the home landscape. Be careful to keep the mulch away from the base of the tree to prevent water retention.

Link: Citrus in the Home Landscape –

  • Matt was asked next about trees that flower but don’t produce fruit:

Two guesses to the reason are irrigation being off (too much or too little), the other is too much fertilizer at one time particularly when the tree is setting fruit. This is especially important when the tree is flowering as it can discourage reproductive growth. Danielle added that it is not uncommon for citrus to have a “June drop” of fruit.

  • The panel went back to Matt to discuss using permaculture concepts with citrus trees.

He said this will work with citrus though you’ll want to remember the tree may have a larger canopy so something like lettuce (Lactuca sativa) may be a better option to grow below the tree and to avoid vining plants in this scenario. Keep in mind the local environment and that we have a higher moisture level so spacing your crops apart is important to avoid disease pressure.

  • Danielle next answered a question about when to harvest the fruit of your citrus tree:

She said that the commercial growers use a Brix to acid ratio, but that requires special equipment which most homeowners don’t own. A better solution for homeowners is to watch for color break (this is when your fruit changes from green to its mature color) and begin tasting the fruit at this time. Things here tend to be ready Oct-Dec (may differ based on variety), and you’ll want to remove the fruit at that point. Leaving the fruit on the tree through winter may result in a loss in a hard freeze.

  • Beth was then asked about citrus pruning:

She said that in a home scenario, you’ll not need to prune much. It’s okay for your trees to look different. Pruning involves the removal of dead or diseased wood to a live bud or lateral shoot. You can also remove any branches which have become too large or out of bounds. As well any branches growing too close to the ground can be taken off. Also, any suckers originating from the root stack should be taken off. Finally, any aggressive growth through the center of the plant should be cut off. Branches that are growing downward don’t necessarily need to be removed completely unless appropriate to do so.

Link: Citrus Pruning and Recovery – Citrus Recovery and Pruning – YouTube

  • Next, Matt was asked about using kumquat as a hedge:

He said it is possible and has been done commercially to ease equipment use or promote health after the plant is harvested. He emphasized Beth’s thoughts on cutting back to a lateral bud to simplify making a hedge from citrus. One plant he said will do well in this scenario is a trifoliate orange (Poncirus trifoliata), but keep in mind their thorns.

Link: Citrus pruning –

  • The panel finished with a few questions for Danielle on insects:

The first was what is and what to do about wrinkled leaves on your citrus:

To this she said the damage is most likely old citrus leaf miner (Phyllocnistis citrella) insect injury. These are the larval form of a moth which lays eggs in new growth of citrus. The biggest signifier of this are lines or tunnels throughout the leaf. As the tree grows, the leaves are stunted and become curled. There is nothing that may be done about these as the larvae have grown and moved on. It will not harm the tree aside from destruction of photosynthetic materials but is generally not broad ranging. The effect is cosmetic and will not cause harm to the tree or yield.

Link: Citrus Leafminer –

The next question was about insect protection through the summer using natural products.

She began by emphasizing the FFL concept of right plant, right place. Essentially, make sure you’re setting your plant up to thrive. Once you’ve picked the proper spot, purchase a disease free tree from a certified nursery that has been inspected and is tagged. You’re likely to see leaf miners as discussed above or “orangedog” caterpillars. These are the larval form of the giant swallowtail butterfly (Papilio cresphontes) which are a pollinator. She pointed out that pest identification is crucial. One example is a friendly fungus that is entomopathogenic and attacks white fly nymphs. That said, there are natural solutions such as neem oil and Spinosad. You always want to know what you’re controlling and make sure you follow the label for all pesticides.

  • The program wrapped up with a question to Danielle about citrus resources for novice growers:

She began with our Gardening in the Panhandle newsletter. Another resource recently launched from the Citrus Research and Education Center has videos on everything from planting to insecticide use in citrus.

Link: CREC Home Citrus –

Citrus trees are a wonderful addition to your home landscape. As with all plants, there can be challenges growing them. A little patience and knowledge will go a long way to helping you grow a beautiful tree that can provide a bountiful harvest. Your local extension professional is always on hand to help.  Reach out to us at this link: local extension agents.

This program has been recorded and is available on Facebook here:

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The Price of Mowing

The Price of Mowing

It’s early spring which means time to pull the mower out of the garage and turn that engine over for the first time in months. As with most years, this task may be easier said than done. You fill the tank, check the oil, then pull that string hoping to hear that engine hum to life. Instead with a disappointing spurt, it putters back to sleep. Discouraged, you bounce between the carburetor and spark plug just knowing there is a simple solution. Finally, everything gets cleaned then reassembled, you pull that cord but this time the mower springs to life. As you stand there feeling the cold air on your skin you survey the lawn and think about how little you’re up for this effort today. Why not take another month off of this lawncare duty by partaking in your Panhandle horticulture agents’ “No-Mow March” initiative. Doing so can not only save you the early season frustration outlined above but may help you hold on to a little bit of your hard-earned dollars.

The Underlying Cost

It’s time we talk about the price of cutting your grass. A universal expense should you push your mower or ride on top is gasoline. Have you ever taken a minute to determine how much it costs to mow your lawn across the course of a season? For our purposes here, we’ll consider a single season to be March through September. Assuming you mow weekly as you should, that accounts for 28 sessions. On average, assuming your grass is dry, a walk behind mower will burn through about a liter or roughly a quarter gallon per acre of mowed lawn. With gas prices in Florida running at $3.45 per gallon according to AAA, that will cost $24.15 to cut your lawn across a single mowing season. Riding mowers exacerbate this even more burning through half to three quarters of a gallon per acre mowed. To be fair, they have a bigger job being as they must propel their own weight and that of the operator. In this instance, the cost of gas can run you anywhere between $48.30 and $72.45 in a season.  All of this assumes that your mower is running efficiently. Why not cut yourself and your wallet a break and avoid mowing at all early in the season.  Sit back and relax for a while longer this year and skip mowing in March and save yourself a little time and money. Your neighbors may complain. Tell them you’re helping both your back and the bees.

IFAS Photo


Early spring begins with emerging pollinator species. They spent the winter months holed up in their nests bunkered against the cold weather. Around March they stick their heads out and begin looking for nearby nectar sources. A good place to start is with the flowers which have popped up in your yard over winter. We see them as weeds, but to these titans of pollination they might just be the key to life.

Butterfly on flower
Monarch (Danaus plexippus), Butterflies in the McGuire Butterfly Garden, flowers, plants. UF/IFAS Photo: Sally Lanigan.


Information on “No-Mow March” may be found by heading over to our information page located here. Information on pollinators may be found on these Ask IFAS documents or by contacting your local extension agent for this and any topic regarding your gardens and more.