Welcome to the Ira Nelson Horticulture Center's Info Center where you can find everything from garden tips to answers to frequently asked questions.
Late summer and going into fall may be considered a time of renewal in the garden. Warm season summer crops may be growing well or just ending their season while the fall and winter crops are just starting.
From August on is a poor time to establish a permanent turf grass from seed and this process should be postponed until the following spring. However, solid sod or over-seeding with a high quality lawn ryegrass may be done to control erosion. Consider October-mid November when planting lawn ryegrass in south Louisiana. Little or no nitrogen should be applied to the warm season grasses because the nitrogen may encourage new growth which may be damaged by frost. These warm season grasses may benefit from a little extra potassium to strengthen the plant for the winter.
Fall is an excellent time to plant shrubs and trees. This allows time for the root systems to become established in the cool soil before the flush of growth next spring. This means that the root system is growing in the winter while the top is going through a period of relatively inactive growth.
For the fall ornamental garden, the gardener may start one of two ways depending upon the plants desired. In most cases the gardener may start with seeds or transplants, normally in some type of cell pack. Seeds suitable for direct seeding which are available for the fall garden include, but are not limited to alyssum, Johnny-jump-up, calendula, annual phlox, and nasturtium. Nasturtium may also be purchased as transplants; however be careful when transplanting so as not to disturb the root system in the transplant process. Other direct seeded items may include larkspur, and sweet peas which are grown for flowers and fragrance. Many other cool season crops may be grown in the flower garden. Additional plants found in the winter garden are statice, delphinium, hollyhock, some poppies, sweet William, ornamental kale and cabbage, blue bonnet, snapdragon, stock, lobelia pansey, viola and even petunias. In south Louisiana petunias do very well in the cooler periods of the year, whereas in hot dry climates petunias may be found growing in the hot part of the year. Last but not least we should not overlook the ever diverse chrysanthemum.
Rose growers should have all roses that need pruning pruned by no later than Labor Day. Remember to take out dead and diseased canes as well as removing the very thin weak growth. This weak growth never develops into anything of value. Look for insect infestation and continue to spray for black spot, an ever present disease which plagues roses and if left unchecked can cause serious damage. Late September should be the cut off date in south Louisiana to apply fertilizer to roses. This should be a light fertilizer application because growers do not want or need excessive grow on the bushes going into winter. Because of the cooler day conditions, and especially of the cooler nights, beautiful roses may be produced in the fall. Some growers consider the fall flowers to be better than the spring flowers.
Spring flowering bulbs should be purchased in the fall and in some cases need to be chilled. Tulips need a chilling period of 8 -10 weeks before planting. Generally, with regards to the selection of bulbs, the bigger the better. The larger the bulb the more stored food it has and the more flowers it has or is capable of producing. Pick large and firm bulbs which do not have cuts or bruises. Many of the bulbs may be planted in October and November, however tulips may also be planted in December and even into early January. Most bulbs will do well the first year because the bulb is full of food and in some cases buds, so a grower ends up forcing the bulb. Re-blooming of many of the bulb crops may be questionable. One notable exception would be narcissus and some of the daffodils that not only grow here, but thrive.
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Poor pecan nut quality may be the result of one or several problems. No nuts on the tree may be the result of poor pollination in the spring. Poor pollination may be an environmental problem, such as too much rain, or too low humidity. Big pecans and no meat might be the result of poor nutrition or the lack of moisture in the latter stages of nut development. On the other hand, if the pecans are small (and they should be of a large size) and are filled out with meat then one possible problem might be poor nutrition or the lack of moisture in the early stages of development. A home owner who has a few trees may easily provide adequate water to the few trees. As a general rule, during the growing season, one inch of water once a week is adequate to produce a respectable crop. One inch of water is easily determined by placing the sprinkler under the tree and placing two or three cans (the types which have commercially processed vegetables) on the ground in the area where the irrigation is being applied. When the cans have one inch of water in each then the gardener has applied one inch of irrigation. Severe insect and/or disease damage may stress the tree and this may influence the size of the nut or the quality of kernel inside.
When pecans start to fall it is best to pick the nuts from the ground as quickly as possible and allow them to dry. The longer the pecan stays on the ground the more moisture it absorbs, which may cause discoloring. Adequate drying in a protected area normally takes place in about two weeks. To determine if the nuts are dry, take a few, crack and remove the kernel. Take the kernel and bend. If it is soft and continues to bend then it is probably too moist and should be dried more. However, if it snaps, it is probably dry enough to store. Cool to freezing extends the shelf life of the meat. If stored in the refrigerator or freezer, place in an air-tight container because the meat will absorb odors in the refrigerator or freezer.
Pears should be harvested before they are ripe and a little on the green side to avoid insect, bird, squirrel and other damage. Another reason to harvest slightly green and allow to soften is to avoid or reduce the numbers of "stone" cells, the cells which develop into small sand-like structures.
It's strawberry time -- that is time to plant the plants. Strawberry plants should be set in November in south Louisiana for the following spring production. There are a few annual berry plants which may be purchased and planted in the spring, but best results are achieved when perennial plants are set in the fall.
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Those who like the wonderful crops of fall and winter may be planting a range of items. Look to plant beet seeds as well as broccoli seeds or plants. Brussels sprouts, a little more challenging to grow may be started along with the wonderful cultivars of Chinese cabbage, cauliflower and collards. Garlic and onions may be considered at this time. Gardeners should not overlook turnips, spinach, rutabaga, radishes and even snap beans. Lettuce may be planted and normally the leaf lettuce types do better in south Louisiana. Most other cool season crops may also be planted at this time. When planting leafy items like lettuce and greens, consider planting at 2-3 week intervals to have an extended harvest period. It is not recommended to over-plant; however if leafy plants are too thick consider using these tender leafy plants in a green salad, don't let them go to waste. Beets are easily over-seeded because the seed a gardener plants is actually a dried fruit which may contain 3-5 seeds. This means each time you plant one beet "seed" it contains 3-5 seeds. As a result, when the seeds sprout the resultant plants are often too close together which prompts the need of thinning. Again, these tiny tender plants may be used in salads. Also, broccoli leaves may be cooked or eaten raw just as the flower buds are consumed.
Snow peas (edible pod types) and English peas may be planted now to avoid the hottest time of the summer and the cold periods of winter. The goal is to get pod set after summer and before cold weather.
Gardeners who planted Winter Squash and Pumpkins earlier should be harvesting now. Harvest these when a good typical color develops and the rind becomes hard. Cut from the vine and store off the ground in a cool, dry place. These fruits normally last for months in a usable condition.
Please be sure to bookmark this page and check back for more seasonal gardening tips and updated planting advice!
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- Container Plantings
- Caring for Plants in the Home
Q. Is an amaryllis hardy?
A. Most Hippeastrum species will survive outdoors in south Louisiana and do well.
Q. Can an amaryllis bulb be potted?
A. Yes. It prefers to be somewhat potbound in sandy soil; needs bright light, lots of water before blooming. Pot 1 inch wider than the bulb with top above soil line.
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Q. My bougainvillea is several years old. I keep it in the garage every winter. It is fertilized regularly and gets plenty of sun. It blooms sparsely. What does it need?
A. This is a very commonly asked question and the answer, most of the time, is that the plant is not getting enough sunlight. Bougainvilleas need 8-10 hours of direct full sunlight every day. Also, cut back on the water and fertilizer and only water when the plant wilts. If you can, use a blossom booster fertilizer every 2-3 weeks. Some types of bougainvilleas bloom mostly in the fall in response to short days.
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Q. How long do daffodils and tulips have to be kept in the refrigerator before planting?
A. Daffodils do not have to be refrigerated. Tulips should be chilled 8 to 10 weeks before planting.
Q. If tulip bulbs have already been chilled when purchased, is it fine to go ahead and plant them?
A. The best thing to do is to re-chill because you do not know how long the tulip bulbs have been sitting out in the warm environment.
Q. When is the best time to plant tulips?
A. Mid to late December. Consider planting groups of bulbs two weeks apart for an extended bloom. Space bulbs randomly for a more natural look in the flower bed.
Q. How do you force tulip bulbs?
A. Chill in the vegetable bin of the refrigerator for 8 to 10 weeks then plant in pots with planting mixture of potting soil, sand vermiculite and bone meal. Plant bulb tops one inch below the soil line and space one inch apart. Water well and place in a dark place until shoots appear. Move to bright light. Always keep in a cool room and water as needed.
Q. Will forced potted tulip bulbs produce next year?
A. Probably not. Growing conditions (not forcing) are not conducive for the bulb to produce green leaves to store food and set a floral bud for the following year. Also in south Louisiana, the night temperature is too high for tulips to store adequate food to produce a flower. Generally purchase new tulip bulbs annually, enjoy, and discard plants.
Q. What causes sparse blooms on daffodils?
A. Planting too shallowly causes bulbs to split quickly into many small non-flowering offsets. Bulbs should be planted at a depth twice the diameter of the bulb itself. Divide every fourth year or so after leaves have died off in early summer. Dense shade reduces the number of blooms.
Q. When can you dig daffodils and replant?
A. Wait until all green leaves have thoroughly dried. Cutting green leaves off reduces the overall health of the plant. Then they can be dug, dried, treated for fungus, and replanted in the late fall – November or December.
Q. An Easter lily is planted on the east side of the house and is growing well. It looks healthy. Will it bloom?
A. It probably will bloom. Easter lily bulbs in the landscape normally bloom in mid-summer. For Easter enjoyment, Easter lily bulbs are forced.
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Q. Can caladiums be planted indoors?
A. Yes. While growing, caladiums need night temperature in the high 50's and days around 80, constantly moist soil and fertilizer every other week. They are at their best in bright indirect light and normally do not grow as well indoors as outdoors.
Q. How do you care for caladium bulbs over the winter?
A. Life tubers in fall. These tubers may or may not have green foliage. Dry in warm place above 40 degrees. When tops die back, clip off. Clean tubers gently and dust with sulphur and store where they are cool but will not freeze. Try to keep bulbs from touching each other to reduce the spread of disease. Store in dry peat moss, vermiculite or perlite.
Q. When is the correct time to plant caladium bulbs?
A. Wait until soil temperature reaches at least 70 degrees. Caladiums should be one of the last plants to go into the garden.
Q. Can caladium bulbs (tubers) be saved from year to year?
A. Yes. Dig in the fall before frost and allow to dry in a well-ventilated but shady area. After 7 to 10 days, remove leaves and dirt then pack in dry peat moss, vermiculite or similar material for storage. Pack tubers so they do not touch each other. Dust with all-purpose fungicide such as Captan as you pack. Place container in an area where temperature won't drop below 50 degrees F. Many people are very successful at saving tubers from year to year and their tubers get larger and larger.
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Q. Could you give some tips on making a mixed container of annuals?
A. Many gardeners are very successful with mixed containers, using several varieties of flowers and foliages in pleasing combinations of color and texture. Almost any type of plant can be combined with a few guidelines.
Design the container plantings for shade or for sun, combining only those flowers, which do well together. This means to group plants together which have similar cultural requirements - similar sun requirements and similar watering requirements. Keep in mind that annuals peak at different times of the year: summer vs. fall. Semperflorens bronze-leaf begonia or any of the green-leaf begonias, impatiens, and red salvia and coleus all work well in containers for shade. For a sunny location, the choice is almost unlimited.
To add interest include plants for height (e.g. shasta daisies or geraniums), plants for spreading (e.g. petunias), and plants to grow down over the edges of the containers. Trailing foliage plants are useful here as well as those that flower such as verbena.
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Q. I have several hibiscus and I'm having a problem with buds falling off prior to opening.
A. The buds are probably falling off of your hibiscus because of tiny insects called thrips eating on and damaging the buds at a very young age. The thrips must be eliminated by using an insecticide. You can use one of the organic insecticides such as Organic Plus or you can use a longer-lasting insecticide such as Orthene. Spray as recommended on label. Keep in mind that hibiscus need at least 8-10 hours of direct sunlight which is required for most hibiscus to bloom profusely.
Q. Every summer it seems a certain pest attacks my hibiscus by eating the leaves. Do you have any idea what kind of pest this may be and what kind of spray should I use?
A. The critters doing the damage are larvae of a chewing insect. When the first damage is noticed, use the organic worm killer named Dipel (dust) or Biological Worm Killer – Thuricide (liquid) that contains Bt ( Bacillus thuriengensis ). Apply as recommend on the product label. The worm eats the Bacillus, becomes sick, and dies.
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Q. I have some large, healthy hydrangeas that refuse to bloom other than perhaps one large bloom per year. What is wrong, why won't they bloom?
A. If you are meeting water and sun needs, the only other obvious cause of lack of bloom is improperly timed pruning. Prune the plants immediately after bloom, so that the new growth will be able to develop flower buds in the fall. Pruning in the spring or early summer removes the fall-developed flower buds, preventing bloom for that year.
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Q. I have an impatiens with variegated leaves, which I can successfully propagate with cuttings but none of the seed I have saved from it will sprout. What is the trick to making the seed grow?
A. The impatiens you are growing is probably one of the New Guinea hybrids, which normally do not produce fertile seeds.
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Q. What can I do to re-bloom poinsettias?
A. Check your poinsettia daily and follow these tips. Water your poinsettia frequently but don't drown it and keep the plant out of drafts. Place the plant in good light inside the house. And finally, after blooming, prepare the plant to bloom again next year.
Poinsettias are perhaps the most difficult flowering potted plants to rebloom indoors. Fortunately in the warmer areas of south Louisiana, poinsettias can be planted directly out-of-doors in the spring after the danger of frost is past. If placed in a protected area where early fall frost won't harm it, they will make beautiful plants and flowers for the next holiday season.
Make sure that the outdoor poinsettia receives only natural sunlight. Any additional light from cars, the yard and streetlights will inhibit blooming.
Generally speaking, blooming or re-blooming of poinsettias should be left to professionals.
Q. Will poinsettia planted in ground freeze?
A. Yes, however it will come back from the rootstock.
Q. How do you care for a poinsettia in the home?
A. Keep damp, not wet, and in bright light. Keep it out of drafts and away from heating ducts.
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Q. When do you prune roses?
A. Hybrid tea, Grandiflora and Floribunda roses require annual pruning in the spring just prior to bud break. If rose bushes are pruned too early, injury from late frost may make a second pruning necessary. Climbing roses should be pruned in the fall, any time after cold weather sets in. Old rambler roses should be pruned immediately after flowering.
Q. When and how do you start rose cuttings?
A. Roses can be started from terminal cuttings covered with a fruit jar. These cuttings may be either placed directly in the ground or in a container. However, because all hybrid roses are grafted onto a common rootstock you should buy the variety you want that is already grafted. Old fashion/antique roses may be grown on their own roots.
Q. Does the petal count of roses determine the number of days before subsequent blooms occur?
A. Yes, generally, that is on hybrid teas. If a flower has forty petal blooms when cut, then it will take 40 days to rebloom. However, this is a very general rule of thumb.
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Q. When do you dig tiger lilies?
A. After the foliage has died down naturally. Usually this is the opposite of their bloom period. Plants blooming in the spring should be dug in the fall. Plants blooming in the fall should be dug in the spring.
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Q. Please tell me what disease looks like small bits of cotton on my houseplants and what to do for it.
A. The appearance of what looks like small bits of cotton on houseplants is not a disease, but is an insect: mealy-bugs, a sucking insect pest. Mealy-bugs are soft insects that have a whitish, cottony or mealy substance around them.
Q. I have a fairly large weeping fig plant in my house that has developed a clear, shiny coating on many of the leaves. The plant still looks good. Is this something to worry about?
A. The shiny coating on the weeping fig leaves may be a residue left behind from aphids feeding (sucking) on the newer growth; scale insects can also leave clear secretions. Sap that has been secreted from the leaves may also be the cause of the coating.
Q. How can I tell if my houseplants are getting the right amount of light?
A. One of the most common signs of inadequate light is yellow and dropping leaves. That is also one of the most common signs of too much light. To figure out if either of these situations is your problem, you will have to look more carefully at your plants. Flowering plants that don't flower, any plants with leaves angled toward the light and long, spindly stems, or plants whose new leaves are smaller are all showing signs of inadequate light.
Q. It gets very dry in my house in the winter. Does this hurt my plants? What can I do to help?
A. Most plants prefer a relative humidity of 50-60% or even higher. During the winter, most homes have a relative humidity of 10-15%. Such low humidity can cause plant leaf edges and tips to brown, flower buds to brown and fall, or generally keep the whole plant from thriving. The best solution is to use a humidifier of some sort to raise the relative humidity. Even better, group the plants on a tray of moistened pebbles or long-fibered sphagnum moss. This will raise the local humidity to an acceptable level. Misting the plants once or twice a day helps, but is really a very short-term remedy.
Q. What kinds of fruit trees can I grow indoors?
A. Calamondins, lemons, limes, kumquats and other citrus are good choices for indoor gardening and will often bear successions of perfumed flowers and fruit.
Q. Request for plant recommendations for low light.
A. Aglaonema, , Cast Iron Plant, Spathyphyllum, Dracaena, Chinese Evergreen, Heartleaf Philodendron and Devil's Ivy.
Q. Older leaves on ficus tree in greenhouse have brown spotches on back and leaves eventually fall off.
A. Check for scale insects.
Q. Can you prune indoor ficus tree, the ones with small leaves?
A. Yes, and they can be pruned rather severely. Prune as you would a normal tree by thinning out branches. It is probably best to not top the tree!
Q. How do you induce bromeliads to bloom?
A. As a general rule the minimum time for flowering is three years from seed or vegetative propagules (pups). If your bromeliad is mature and still not showing a flower bud, a change of environment is in order. First apply fertilizer rich in phosphorus. If this doesn't work, try placing the plant into a brighter and/or warmer spot. Should all these techniques fail to produce flowers within a year, it is time for the apple-in-the-bag trick. First pour off any water in the bromeliad cup. Obtain a fragrant ripening apple and enclose it and the bromeliad in a sealed, clear plastic bag. Keep the bagged plant out of the sun, but in a warm place. After one week remove the bag and apple and return the bromeliad to its former location. This should trigger it to bloom in time.
Q. How do you remove deposits of salts from clay pots?
A. Soak in a solution of one part bleach to nine parts water. This will not completely remove the salts from the clay pot.
Q. What is causing ficus tree to lose leaves. I took it outside and sprayed it with malathion. It has not been repotted in at least 6 years.
A. Ficus are very picky plants when it comes to losing leaves. Possible cause was moving the plant around. Put it in a location where you want it and do not move it.
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