Plant: Fruit set of many vegetables are sensitive
to high temperatures, so plant okra, Southern peas, peanuts, sweet
corn, watermelons, cucumbers, squash, cantaloupes and eggplant
during the first part of May for best results. High temperatures,
both day and night, interfere with pollination and fruit set in
many vegetables. Snap beans tend to drop their flowers readily
under these conditions. Squash has a tendency to produce a large
number of male flowers (the ones without the small fruit attached
to the base of the bloom) and, consequently, few fruit. Okra,
Southern peas and eggplants will continue to set fruit in the
summer. Caladium corms are planted now. Wait until the soil warms
and night temperatures are above 60 F. Caladiums prefer a loose,
well-drained soil with plenty of organic matter. They thrive in
shade with dappled light, and their colors of green-white, green-pink
or green-red fit into almost any landscape. For more information
about caladiums and for a listing of those which endure in the
Plant sun-loving, heat tolerant annual flowers such as portulaca,
purslane, copper plants, lantanas, and ornamental peppers. Do
not transplant vinca (periwinkle) until June after the rainy season
is over. Seeds that may be sown directly in the warm soil include
amaranthus, celosia, morning glory, sunflowers and zinnias. Plant
hibiscus, bougainvillea or mandevilla vines in containers for
tropical landscape color. If deer are a problem, choose from a
Prune: Prune pillar or climbing roses as soon
as they have finished their major bloom to allow time for the
development of new canes for next spring's blooms. Prune storm-damaged
tree branches immediately after damage occurs. Vigorous vines
such as wisteria or landscape shrubs such as pyracanthas and elaeagnus
will need frequent pruning during the active growing season.
Fertilize: If you have not applied fertilizer
to the lawn, May is a good month to fertilize lawn grasses AFTER
the lawn grass has been mowed twice. Slow release fertilizers
are best because they feed throughout the growing season and do
not leach (wash) into the ground water. Use a fertilizer spreader
to get even distribution and use settings recommended on the fertilizer
bag. Yellowing leaves with darker green veins signals symptoms
of iron deficiency, which is common in alkaline soils. Apply iron
sulfate (Copperas) onto mulches or decomposing organic material
(compost) to make a slow-release, chelated product. Soils cannot
be permanently made more acidic by the addition of sulfur or even
pure sulfuric acid because of the buffered (hard-to-change) nature
of the calcareous soils. Fertilize container plants and hanging
baskets plants on a regular basis with a water-soluble fertilizer
product and be sure that a slow-release fertilizer such as Osmocote
has been mixed into the potting media at the label recommended
Odd Jobs: After spring bulbs have finished flowering,
wait until the foliage turns brown before cutting it off. Food
is being manufactured and stored for next year's blooms. Mulch
plants to reduce watering requirements, suppress weed growth and
minimize soil temperature changes. Peach fruit should be thinned
to six to eight inches apart along the fruiting branches which
generally leaves about 600 fruit per mature tree; apples and pears
should be thinned to one fruit per spur or cluster.
On the Lookout: To encourage more rapid re-blooming,
pinch off old flowers on bedding plants after their first flower
cycle is completed. Roses may encounter insect problems. Watch
for aphids on tender new growth, thrips on flowers and cucumber
beetles on foliage. Beetles are especially a problem if a vegetable
garden is nearby. Fear not, this is the normal season of leaf
shed for photinias, gardenias, ligustrums, pittosporums and magnolias.
For questions about various garden problems, consult the massive
horticulture database of questions-and-answers at:
To learn how to effectively and efficiently search for information
on Aggie Horticulture - PLANTanswers, see:
May Calendar by Dr. Tom Harris
· Get the begonias and impatiens in quickly if you expect
them to fare well when the heat arrives. Wait to mid-month to
plant periwinkles. Do not water overhead.
· Mandevilla, bougainvillea and Chinese hibiscus are great
· Don't plant vinca until at least June 1.
· Deadhead (pinch/cut off) spent flowers to encourage more
· Hot weather plants include firebush, lantana, poinciana,
esperanza, firespike, caladium, coleus, begonia, moss rose, hibiscus,
bougainvillea, purslane, cannas and blue princess verbena.
· As the weather gets warmer, regular fertilizing of your
pot plants with a water soluble product will bring rich color
to your environment.
· Roses should be blooming with color. Continue to fertilize
them for continued blooming.
· Let your wildflowers go to seed before mowing.
Fruits and Nuts
· Peaches are ready to harvest when the base color changes
from green to yellow.
· This is the month for pecan casebearer. On or about May
10, apply lorsban or Malathion to reduce casebearer damage to
· Pick peaches, apples and plums as soon as they ripen.
· Keep suckers pruned off your fruit trees-they come from
the root stock and will take over if unattended.
· Keep fruit trees well watered as long as there is fruit
on the tree.
· Control army worms and web worms with Bt or Malathion.
Bt must be applied when the worms are feeding.
· If you collected bluebonnet seeds, hold them in paper
bags until fall.
· Firebush for full sun and firespike for full shade are
two of the best hummingbird plants. Hibiscus, cigar plant, dwarf
Chinese trumpet creeper and firebush on the patio will bring hummingbirds
in close for observation.
Shade Trees and Shrubs
· This is NOT a good month to prune oak trees. The oak
wilt fungal spores and sap beetle carriers are active. If you
must prune, be sure to paint with a latex-based paint immediately
· If you have red-tipped photinias and the leaves are getting
black spots with the whole plant turning yellow, bite the bullet
and remove the affected plants and replace them with a holly species.
· If your red-tip photinias require constant pruning, consider
replacing them with holly, nandina, xylosma, eleagnus, or pyracantha.
· Be careful with the weed-eater around young trees. One
trip around the bark at the base will kill it.
· Summer weight oil does a good job of temporarily controlling
scale on euonymous and other shrubs. Follow the instructions carefully.
· Leaf miners make translucent trails on the leaves of
Texas red oak and other plants. They can be controlled early with
Bt, but usually are not a major problem.
· May is the best month for starting a new lawn. Our recommended
grass varieties respond well to the warm weather and there is
time for it to get established before the summer drought.
· Don't bag those lawn clippings. Let them fall to the
soil to compost and return nutrients to the roots of the grass.
· May is the only month to fertilize buffalo grass.
· If you're starting a new Bermuda grass lawn, use 2-3
lbs. of seed per 1,000 sq. ft. on well-prepared soil and water
twice a day. It will be up in 3-6 days and need mowing in about
· Your St. Augustine grass will fill in drought-killed
areas quickly if you can water regularly. Water when the grass
doesn't spring back in your footprints as you walk across it.
· Place several tuna or cat food cans around the lawn and
measure how long it takes the sprinklers to put 1 inch in the
cans. That's how long you set the timer on the sprinkler system.
Usually, a properly maintained system will put out an inch in
5-6 minutes. Running your system for this period of time is all
that is necessary to maintain a nice, green lawn. Train your lawn
to be drought resistant by only watering when the grass needs
it and then water deeply. The equivalent of 1 inch of rain per
week is all that is necessary to keep St. Augustine grass healthy.
· Tomatoes are ready to pick when they change from green
to green-white color. For maximum production, pick them at this
stage and let them ripen on the kitchen counter. If you leave
tomatoes on the vine until they ripen, the vines will stop producing
thinking they have "done their thing" for the year.
· Keep the tomatoes well watered and mulched to avoid blossom-
end rot. Avoid watering the leaves.
· Side dress vegetables with 1 cup slow release lawn fertilizer
per 20 feet of row every 6 weeks.
· Harvest, harvest, harvest. If you don't, production will
slow or stop.