Sunn Hemp for Home Gardens

Sunn Hemp for Home Gardens

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.

Sunn hemp

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.

Sunn Hemp as a cover crop

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.

Hollies for Winter Interest

Hollies for Winter Interest

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.

Holly Tree

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.

Holly branch suffering dieback

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.

The Chemical Properties of Soil

The Chemical Properties of Soil

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.

Nutrient availability chart

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.

depiction of nutrient being held through cation Exchange

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.

 

The Physical Properties of Soil

The Physical Properties of Soil

Understanding soil composition is crucial for successful gardening. Soil is the slow interaction of parent material with regional climates, topography, and soil biota over millennia. The breakdown of parent materials results in layers of material called horizons. A subset of soil science is dedicated naming soils with similar horizon development. In North Florida, three of these soil types predominate. Near the northern border, we find ultisols, these sandy soils have a higher clay content and are suitable for row crops with proper management. Through the center of the Panhandle counties, you’ll find entisols. These are sandy and undeveloped, thus requiring close attention to irrigation and fertilization. Finally, by the coast are spodisols rife with mineral pockets and known for being waterlogged. All are usable for plant growth, and with little knowledge of cultural practices can make your landscape thrive.

Soil horizons of ultisol

Soil horizons of ultisols
Photo: USDA/NRCS

The Panhandle Parent Material

In Florida’s panhandle, the parent material stems from the Citronelle formation transitioning into the Miccosukee formation around Gadsden County. The Citronelle formation consists of unconsolidated quartz (sand), gravel, clay, and mineral deposits from rock formations in the Appalachian Mountains. Clay associated with this formation is the basis for the ultisol concentrations in the northern portion of the state. Alluvial flow or deposits left by rivers washes the sandier particles down into the center portions of the panhandle, and siltier particles flowing to the coast depositing minerals as they settle. The Miccosukee formation is similar but has different textures and particle sizes in the quartz deposits. Knowing where your soils originate will help you understand two major aspects with regard to soil’s physical properties. Those being texture and aggregation.

Soil Texture

Soil, a blend of sand, silt, and clay, is not just the ground you walk on but the very foundation of your garden. These components, deposited in your location through natural processes (as outlined above), have been blended to create a soil unique to your garden. Sand is the largest of these particles, with silt considerably smaller and clay smaller still. This size difference, means there will be air spaces known as pore space within what appears to be a consistent material. These spaces comprise approximately 45% minerals, 25% air, 25% water, and 5% organic matter. Higher sand soils have larger pore spaces which facilitates water flow through that soil profile. What that means for your soil is less water holding capacity and higher losses of nutrients. In contrast, higher clay percentages have smaller pore spaces which coupled with charges at the atomic level are better at holding onto water and nutrients. Understanding your soil texture is key to determining the right timing for irrigation and fertilization while providing insight as to potential aggregation of your soils.

Soil Texture Triangle

Soil Texture Triangle
Photo: USDA

Aggregation

Soil structure is an often overlooked aspect of garden management. Well structured soils resist compaction, hold on to water, and retain plant nutrients. They also provide growth space for roots which have access to the resources they need to fuel healthy plants. Conversely, poor soil structure makes your garden more susceptible to ponding and inhibited plant growth. Soil aggregation is what provides this structure. Aggregation is the conglomeration of soil particles bound through chemical bonds and physical forces bolstered by soil biota. Aggregates form through a few mechanisms both inherent and dynamic. Inherent factors include clay content which form and break with changing moisture levels. Other inherent factors include those minerals inherently present in the soil such as calcium. Dynamic factors include levels of organic matter, and those fauna present in that soil.

Soil structure types

Types of soil structures
credit: USDA/NRCS

Maintaining Healthy Physical Structures

Many Florida soils are poorly structured which is why they need to be properly managed for homeowners to have successful gardens. Before you can begin to improve your soil, you must understand your soil’s story. Start with testing for compaction by pressing a screwdriver into the ground.  If this is difficult, you need to take action to relieve the situation and increase the availability of air in your root zone. Tillage is a good way to do so, but be wary as excessive tilling can lead to higher compaction problems long term. Look into conservation tillage as a methodology to avoid this problem. Perform a jar test to understand the texture of your soil and thus its propensity to develop aggregates. For high sand soils, add organic matter to improve structure. Be careful to add smaller amounts at a time as organic matter has an inherent nutrition load and too much may begin to limit nutrients. Cover crop strategies are a great way to add organic matter while keeping soil covered during non-active growth periods.

Soil improvement and management will take multiple growing seasons. Stick to it and monitor your soil to keep your gardens healthy and thriving. For more information on soil, see these Ask IFAS documents, or contact your local extension agent for additional information on this and any topic regarding your gardens and more.

Daylilies in the Landscape

Daylilies in the Landscape

Overview of Daylilies

Spring has begun, and the flowers are making their debut en masse. The daylily is an exceptionally versatile plant that grows in various colors, shapes, and habitats (Hemerocallis spp.). This plant garners its name from a combination of Greek terms meaning “beauty for a day,” given the tapestry a mass planting provides, they live up to that name. These plants tend to bloom repeatedly for 4-7 weeks, though each individual flower only lasts one day. The time of year flowering begins varies by cultivar, but typically, they may be seen beginning in March, with later bloomers starting around mid-May. Add to their beauty that they are also edible, and you have a plant that can’t be beaten.

UF/IFAS Photo: J. Criss

These perennials are widely available as bare-root or potted plants. Both may be planted in Florida year-round, but planning in spring or autumn will increase success. Inspect roots before you plant them, removing any that are circling or damaged. Plant with the crown at ground level, much like a tree, and keep the soil moist until the plant is established.  Though drought tolerant with deep roots, you’ll still want to apply mulch to retain moisture. Fertilizers may be added in spring, summer, and fall based on soil testing. Scouting this planting is important, but insects rarely cause lasting damage. They may be propagated vegetatively or via seed. Vegetative propagation will become important as these plants fill in spaces over the years and will need to be thinned.

Uses in the Landscape

Thanks to the hybridization efforts of growers worldwide, daylilies are available in every spectrum of color and a variety of flower shapes. Daylilies are clumping plants with grasslike foliage and flowers on a scape that may reach up to 36 inches tall. They can be striking when planted in groups of 10, included in a mixed border, or used to highlight a specific area of your gardens. Because they are so varied, it is important to carefully consider the design elements of your landscape and the growing conditions of your landscape when selecting varieties. All cultivars will require some sun, so avoid heavily shaded areas.

Daylily as a border

UF/IFAS Photo: J. Criss

A Note on Color

Your biggest concern when considering daylilies in the garden will be color. When it comes to landscape design, color integration has three main theories. The first revolves around monochromatic flowering. Simply put, except for the green foliage, all flowers in this type of garden will be one color.  Certainly, daylilies fall into this category, which are often yellow and may be quite striking. The second theory on color in your garden spaces is an analogous scheme in which 3-5 colors on the color wheel are utilized to create continual flow.  In this case, find daylilies with red flowers and pair them with violet or yellow flowers. The final theory on color use in gardens is a complementary scheme. In this instance, colors on opposite sides of the color wheel are utilized. The contrast created by this method can create a striking difference that draws the eye to a specific point. Keep in mind that these are all theories. Ultimately, it is your landscape, and you should use those flower colors which satisfy your sensibilities.

Color Wheel

UF/IFAS: Gail Hansen

Daylilies are a wonderful plant for your landscape. Easy to grow with great variety, few others can compete with them. For more information, see this Ask IFAS document. As always, please contact your local extension agent for additional information on this and any topic regarding your gardens and more.