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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Due to several unique challenges home gardeners and nursery owners are often baffled when trying to incorporate roses into landscapes. Consequently, they ignore roses altogether or limit themselves to cultivars in the knockout or drift series. While knockout roses and drift roses are commonly planted throughout the lower south, and deservedly so, many other roses that will perform equally well should be considered for inclusion into landscapes and flower gardens.
‘Anna Jung’ Tea Rose. Image Credit: Matthew J. Orwat, UF / IFAS Extension
While there are several rose classes that will perform well throughout the Florida panhandle, the focus here will be on the Tea class. Roses in the Tea class originated in China over 1000 years ago. Many cultivars of ancient origin reached Europe through trade routes with Italy, England, and France. In the 1700s, the art and science of plant breeding was taking Europe by storm, so horticulturists were crossing the repeat-blooming Chinese roses with well-known European and Middle Eastern cultivars such as the Autumn Damask and Tuscany. Throughout the 1800s, many of these European and Chinese hybrid roses were created to grow around the Mediterranean. In the mid-1800s, Tea roses began to be bred with high centered form and long vase life, therefore aristocratic families throughout northern Europe began to grow them in greenhouses for rose exhibitions and competitions.
At the end of the 1700s and throughout the 1800s, a substantial quantity of Tea roses were brought to the southern USA where they were noted to be of easy culture outdoors. Thus, by the mid-1800s, they graced the gardens of both the humble and the aristocratic. These roses became popular foundation landscape plants from zone 7b to 10, all the way to Bermuda, where many “mystery roses” are found growing today.
Although the popularity of the Tea roses were eclipsed in the 1920s by the showier Hybrid Teas, they have regained popularity in mild-climate locales in the USA due to their ease of culture and prolific blooming habits. Most showy Hybrid Tea and Floribunda roses require fungicide sprays to thrive in the humid Florida Panhandle climate, but most of the Tea roses will thrive without the application of fungicide sprays of any kind. When established, most are drought and insect resistant, and flower well into November and December, unless an early hard freeze occurs. One small disadvantage to Tea roses is that they are more cold-tender than other classes of roses. Almost all these roses will survive well in zones 8a-10, with a few of the climbing types only suited for zones 9a and warmer. None of the Tea in the author’s garden were killed by the December hard freeze, and only a few showed damage.
While there are over 100 worthy Tea cultivars to recommend, this article will focus on five Tea roses:
Anna Jung: Bred in 1903 by Nabonnand, Anna Jung is a showy cream and pink tea in the tradition of other large Tea roses Marie van Houtte and Safrano. It makes a six-by-five-foot shrub clothed in large apple-green leaves. Flower color is variable but ranges from cream and light pink to fuchsia in warm weather conditions. The scent is pungent, like freshly dried green tea leaves. This rose is highly vigorous and free flowering and tough, the author’s plant survived being partially uprooted by Hurricane Michael and is thriving again. Anna Jung was lost to commerce for decades in the United States, imported once again from France, where it has been available in the nursery trade continuously since its introduction. It is now sold by a few specialty rose nurseries in the southern USA.
Single flower of the Tea Rose Anna Jung. Image Credit: Matthew J. Orwat, UF / IFAS Extension
Le Pactole: This Tea rose was bred in 1834 and has been grown in the United States for many years. Some time in the 1930s-1950s it was no longer available commercially and was thought extinct but was found by rose hunters in California and re-introduced to the public in the 1990s. It has light yellow flowers, fading to white, with a lemon-tea scent that floats in the air. This prolifically blooming rose is rather thorny and makes a handsome plant 5 feet tall by 4 feet wide in zone 8a. This rose experiences some dieback under prolonged freezing conditions below 20 degrees F. It recovers well from setbacks and is relatively easy to grow.
Fragrant Tea Rose Le Pactole. Image Credit: Matthew J. Orwat, UF / IFAS Extension
Rosette Delizy: In 1922, the Tea roses were on their way out, but Paul Nabonnand had one last trick up his sleeve with the introduction of Rosette Delizy. This rose was meant to make a splash in European greenhouse rose production with its perfectly formed yellow and pink flowers, but it made an unlikely hit in the Gulf South due to its disease resistance and vibrant colors. Although Rosette Delizy struggles with cold hardiness north of USDA zone 8a, it is perfectly suited to the Florida panhandle.
Especially brightly colored example of Rosette Delizy, a Tea Rose introduced in 1922. Image Credit: Matthew J. Orwat, IF / IFAS Extension
Safrano: Peachy and cream blooms adorn this 4–5-foot plant with an eight-foot-wide, spreading habit. The new growth is deep red, and the foliage is dark green. Safrano can produce the most beautiful flowers in the garden during spring and fall, but summer blooms are small and few-petaled. This rose is ideal for a foundational landscape planting because of its wide stature and nearly evergreen foliage in zone 8b and warmer. Safrano is also one of the oldest available Tea roses, being introduced in 1839.
Spice:Often thought to be one of the original tea roses, ‘Hume’s Blush Tea Scented China’ or the 1830s rose ‘Caroline’, the cultivar we now refer to as “Spice” or “Bermuda Spice” was re-introduced to the horticultural world in the 1970s from the island of Bermuda. Spice thrives in the sub-tropical climate of the Florida panhandle, staying evergreen and producing flowers almost year-round. Blooms are light pink, fragrant, and often borne in clusters. This is one of the most disease-resistant roses of all, rarely showing any incidence of blackspot or powdery mildew. Mature plants are drought and heat tolerant and sit at about 5 feet tall and 4 feet wide.
“Spice”, the Bermuda Mystery Rose, might actually be the original ‘Hume’s Blush’, or the old Tea Rose ‘Caroline’ . Image Credit: Matthew J. Orwat, UF / IFAS Extension
A few notes about Tea rose culture:
They do not like to be pruned back hard, during the first 5 years of growth, only remove dead or diseased wood. Since they are usually sold own root, they need 3-4 years in the garden to become well established. Lastly, Tea roses do not bloom much during the hottest part of the summer but make up for it during late winter and late fall.
Here is a list of mail-order nurseries in the Southern USA that carry tea roses. This list is not exhaustive and does not contain nurseries on the west coast. If any nurseries were left off this list, it is not the author’s intention. No endorsement is made or implied.
Welcome to the world of symbiotic serenity, where ants and aphids work in harmony to create a thriving ecosystem. Ants farming aphids is a fascinating phenomenon in nature, where ants tend to aphids, protecting and nurturing them like precious livestock, while aphids provide the ants with a sweet and nutritious honeydew secretion.
The relationship between ants and aphids is complex and benefits both parties. Aphids, which are soft-bodied sucking insects that feed on plant sap, secreting honeydew – a sugary secretion that aphids produce as waste from their sap consumption. This sweet substance is highly attractive to ants, who actively tend to aphids in order to obtain honeydew as a food source.
One of the most fascinating aspects of ant farming aphids is the behavior exhibited by ants when caring and protecting aphids. Ants are known to carefully tend to aphids, often referred to as “herding”. In doing so, they stroke the aphids with their antennae, stimulating them to release honeydew. Ants then collect and consume this honeydew, which serves as a valuable source of nutrition for them.
Aphids also benefit from this mutualistic partnership by relying on ants for protection from predators such as ladybugs, lacewings, and other aphid predators. In the presence of ants, aphids are less likely to be attacked by natural enemies, which allows them to feed and reproduce more freely. In addition, ants can transport aphids to new feeding sites, which helps aphids access fresh sources of sap.
However, this mutualistic relationship between ants and aphids can also pose problems for gardeners and homeowners. When ants protect aphids from natural enemies, this can result in increased aphid populations and plant damage. Therefore, it is important to control ant farming of aphids in order to manage aphid infestations effectively.
There are several methods gardeners/homeowners can use to manage ant farming of aphids:
Early detection is key. Regularly check for aphids at least twice a week while plants are growing rapidly.
Utilize natural enemies of aphids such as parasitic wasps, lady beetles, lacewing larvae, soldier beetles, and syrphid fly larvae. These insects can help keep aphid populations at an acceptable threshold.
Ant management is crucial. A band of sticky material can be wrapped around the trunk to prevent ants from reaching the aphids.
Prune and dispose of infested branches.
Insecticidal soaps and oils can be used to suffocate aphids. However, these products only kill aphids on contact. Other synthetic insecticides like malathion, permethrin, etc. are alternatives that can control aphids, but they may harm natural enemies and pollinators such as bees.
*Important to note, follow all manufacturers instruction when using chemical products.
In conclusion, ants farming aphids is a captivating example of mutualistic interactions in nature and serve as a compelling reminder of the wonders and intricacies of the natural world.
Do you have a low-growing weed that is producing tufts of white, fluffy, dandelion-like seeds, which float in the wind when disturbed or mowed? This is Annual Trampweed (Facelis retusa). I did not see this weed in North Florida until recent years. It’s native to South America.
Mid-April to early May is the time of year when this winter annual weed goes to seed in North Florida. That’s what it is doing now and it is a prolific seed producer. Each white tuft contains numerous seeds. Each tiny seed is attached to a small individual bristle, coming out of the larger tuft, which is carried by wind. This allows hundreds of seeds to move to other locations.
Trampweed is approaching the end of its life as we move into early May. As a winter annual, the individual weed dies in response to warm temperatures only to leave behind hundreds of seeds that survive the summer. These same seeds come up the following fall to early winter to begin the next generation. The best time to attempt chemical control with an herbicide is well before these weeds mature and begin flowering.
Trampweed in bloom. Credit: Larry Williams
One chemical control option is to apply a lawn preemergence herbicide during October when nighttime temperatures drop to 55° to 60°F for several consecutive nights. This will be just before these winter annual weeds emerge. Done correctly, the application of a preemergence herbicide forms a temporary chemical barrier along the soil surface preventing the winter annual weeds from emerging. Hence the name preemergence.
A second application of preemergence herbicide may be required six to nine weeks after the initial application to achieve season-long control, based on the product’s label directions.
If you miss this narrow window of opportunity to apply a preemergence herbicide, watch for the small young weeds in winter and treat then with a postemergence herbicide that is labelled for use in the type of lawn grass you are growing.
Waiting until trampweed is producing flowers and seeds in April and May to attempt control is almost worthless in controlling this weed. Correct timing is critical.
Trampweed usually is found in areas of a lawn that are already weak and thinning. It favors open, dry, stressed and low-fertility areas of a lawn. So, try to manage your lawn correctly. This involves learning to mow, irrigate and fertilize correctly for the type of lawn grass you are growing.
Sweet potatoes are ideal for filling the gap between summer and fall crops as they have a long growing season. Photo by Janis Piotrowski.
Take the Summer Off, Grow a Cover Crop
As gardeners in the northern states plant and harvest crops until fall, those in the south know that summers can be brutal. In Florida and other areas in the deep south, temperatures can reach triple digits by the summer solstice, and humidity can make it feel like you’re swimming through the air. Pests, from mosquitos to stink bugs, descend quickly, making it no fun to spend hours weeding and watering in the sweltering heat, only to watch your plants struggle to survive. This is why we take advantage of the summer swelter by relaxing with some ice-cold lemonade and enjoying a well-deserved break.
However, while we take a summer gardening hiatus, it’s essential not to leave our soil bare. Fallow soil can become compacted and lose its structure, as there are no roots to create air channels that allow water from frequent summer storms to penetrate the soil. This makes it more challenging for plants to grow in upcoming seasons and can lead to erosion, nutrient depletion, and weed growth. By planting cover crops during the off-season, gardeners can prevent these issues and improve the health of their soil for fall planting. Cover crops offer a multitude of benefits, such as adding nitrogen to the soil, increasing organic matter content, suppressing weeds, breaking pest and disease cycles, and even providing a crop to harvest in the fall.
Fix Nitrogen with Legumes
Cowpea is a summer annual legume that can fix nitrogen, improving soil fertility for fall crops. Photo by Michasia Dowdy, University of Georgia, Bugwood.org.
Summer cover crops are a great way to keep your garden healthy and productive during the off-season, and leguminous crops like cowpeas, soybeans, and sunn hemp can add an extra boost to your soil’s fertility. These legumes have a unique ability to form a symbiotic relationship with nitrogen-fixing bacteria in the soil, allowing them to convert atmospheric nitrogen into a form that plants can use for growth.
Apart from their nitrogen-fixing properties, leguminous cover crops also have deep taproots that can help to break up compacted soil, improve water infiltration, and reduce soil erosion. When planted in dense stands, they can even suppress weed growth, making it easier to maintain your garden’s health.
It’s important to remember to terminate your leguminous cover crops at the bloom stage, as this is when the nitrogen-fixing nodules on the roots are at their peak. By cutting them down at this point, you can help to release the fixed nitrogen back into the soil, where it will be available for future crop use.
Increase Organic Matter with Buckwheat
Buckwheat not only builds organic matter in soil but it also attracts pollinators. Photo by Russ Ottens, University of Georgia, Bugwood.org.
Buckwheat is an ideal summer cover crop for gardens with poor, sandy soil. It is a rapid grower and can produce a large amount of biomass in a short period of time, which can be used to increase soil organic matter content, improving soil structure. The cover crop’s dense, fibrous root system provides ample surface area for nutrient uptake and helps prevents erosion.
Another major benefit of planting buckwheat is its ability to attract beneficial insects, particularly pollinators like bees and butterflies, which can help increase the yield of crops that rely on pollination for fruit set. Additionally, buckwheat is known for attracting predatory wasps, which can help control insect pests. Buckwheat also has the ability to scavenge phosphorus from the soil, making it available for other crops.
To prevent buckwheat from becoming weedy, it is important to terminate it before it goes to seed. This can be achieved by chopping it down when it starts to flower and leaving it to decompose in place.
Suppress Nematodes with Marigolds
French marigolds can help suppress root-knot nematodes. Photo by North Carolina, USDA APHIS PPQ, Bugwood.org.
Nematodes are microscopic, unsegmented roundworms that can be either be free-living or plant parasites. Among them, the plant-parasitic species, such as the root-knot nematodes, can cause severe damage to crops and even lead to their demise. They are difficult to control as they reside underground or inside plants, and nematicides are not easily available to home gardeners.
However, planting cover crops like African or French marigolds before the main crop can significantly reduce nematode populations. These marigolds release alpha-terthienyl, which suppresses not only root-knot nematodes but also other disease-causing organisms.
Apart from marigolds, several other summer cover crops like sunn hemp and velvetbean can also suppress nematodes, especially for root-knot and sting nematode control.
Cover Crops for the Dinner Table
Growing cover crops that serve a dual purpose of providing ground cover during the hottest months and yielding edible produce in the fall is an excellent way to make the most of garden space. Some examples of such crops are sweet potatoes, field peas, and daikon radishes.
Sweet potatoes are ideal for filling the gap between summer and fall crops as they have a long growing season. They have a deep root system that helps break up compacted soil, and their vines provide ground cover, reducing soil erosion. In the fall, their tubers can be harvested after the leaves have died back to make a nutritious and delicious addition to any meal.
Field peas are a versatile crop that not only provide benefits to the soil as nitrogen fixers and ground covers but also offer delicious edible pods if allowed to develop. There are many types of field peas for which to choose, including black-eyed peas, crowder peas, and cream peas. Pods can be harvested in the fall and used to enhance the flavor of stews, salads, and soups.
Daikon radishes are an excellent cover crop that grow deep to break up soil and they have plenty of flavor for the dinner table. Photo by Guodong Liu, UF/IFAS.
Daikon radishes have a deep taproot that can help break up compacted soil, and their foliage can help suppress weed growth. In addition, daikon radishes can be harvested in the fall and can be used in a variety of dishes such as soups, salads, and stir-fries.
Timing is Everything
To make the most of your summer gardening break, plant cover crops as soon as you conclude your spring harvest, typically from late May through early July. Scatter the seeds evenly over the bed and lightly rake them into the soil. It is important to keep the soil moist during the germination period, which typically lasts four to 10 days depending on the crop.
Regular monitoring of your cover crops as they grow is essential to ensure they are terminated at the appropriate time, preventing them from becoming weeds and competing with other crops. Once terminated, you can leave the cover crop residue on the soil surface as a mulch or incorporate it into the soil.
So, this summer, stay cool and let your cover crops take the heat as they improve soil fertility, increase organic matter, prevent erosion, suppress nematodes, reduce weeds, and even provide food for a fall harvest.
