Divide and plant waterlilies and other aquatic plants if not done last month.
Chinese wisteria escaped in the wild, no matter how pretty, is NOT a good thing! Think twice about planting one. Instead, consider the American wisteria Amethyst Falls. It has rich purple flowers and blooms a little later than the Chinese species.
Continue planting daisies, asters, coreopsis, marigolds and sunflowers - they nourish the beneficial insects, which will help keep pests in check.
Divide or transplant hardy perennials such as chrysanthemum, aster and hosta.
For instant color, purchase started annual plants. Select short, compact plants. Any flowers or flower buds should be pinched to give plants an opportunity to become established.
If you haven’t already, it’s time to plant tender summer bulbs such as callas, dahlias, caladium and gladioli.
May is a good time to divide herbaceous perennials that you want to propagate or that are getting too big. Dividing will also help the plant to produce new growth.
Plant a Bonnie herb garden in containers or in a bed near your kitchen. Keep mint in its own pot to control its rampant spread.
Plant caladiums in shaded sites.
Plant containers, window boxes and hanging baskets. Besides adding new annual flowers, consider digging up and using divisions of dianthus, creeping jenny, trailing rosemary, coral bells, hosta and other perennials with good-looking foliage.
Plant moonflower (Ipomoea alba), caladium, coleus, zinnia and other heat-tolerant flowers.
Plant okra, tomatoes, eggplant, peppers, sweet potatoes, Southern peas and other heat-loving veggies.
Seeds of amaranthus, celosia, cosmos, marigold, portulaca, zinnia and other warm-season annuals can be sown directly in the beds where they are to grow. Keep seeded areas moist until seeds germinate.
Sow seeds of beans, beets, carrots, corn (early varieties), cucumbers, lettuce, melons, pumpkins and summer squash.
Transplant Bonnie eggplants, peppers and tomatoes.
Transplant trees and shrubs well before hot weather hits, and keep them well watered.
For best results, transplant perennials before they are 6 inches tall, and don’t disturb spring bloomers until fall.
Apply a high-nitrogen summer lawn fertilizer to encourage a healthy-looking yard.
As soon as azaleas have finished flowering, apply an acid-type fertilizer at the rate recommended. Don’t over fertilize as azalea roots are near the surface and damage can occur. Water thoroughly after fertilizing.
Roses have high fertilizer requirements. For most soils, use a complete fertilizer for the first application just as new growth starts, then use ammonium sulfate, or other high nitrogen source, every 4 to 6 weeks, usually just as the new growth cycle starts following a flowering cycle. For organic sources use cottonseed, rotted manures or alfalfa meal.
Work lime in the soil around your hydrangeas to produce pink flowers or aluminum sulphate for blue.
To encourage flowering, a fertilizer low in nitrogen and high in phosphorus is best. The fertilizer’s three main ingredients are N-P-K with N for nitrogen, P for phosphorus and K for potassium. 10-10-10 means there is an equal proportion of each N-P-K. Hydrangeas like a low N and a high P, thus a combination of 10-40-10 would be ideal.
My general rule of thumb to remember what the numbers mean is to start with the first number and apply from the top of the plant to the bottom. As such, N is for the green; P is for the bloom; and K is for the root or up and down and all around.
To refresh your understanding of pH, pH refers to the acidity of the soil and is measured by the number of hydrogen ions present in the soil. pH is a logarithmic scale based on the power of 10. As such, pH of 6 is 10 times more acidic than pH of 7! Thus, even a little change in pH can make a big difference. A pH of 7 is neutral, less than 7 is acid, greater than 7 is alkaline. Most plants like a pH between 6.5 and 7. Hydrangeas like it more acidic than most plants.
Watch your shrubs for yellow or pale leaves with green ribs – a sign of iron chlorosis. Apply chelated iron according to package directions.
Fertilize azaleas, rhododendrons and camellias after they bloom with a fertilizer made for acid-loving plants.
Annuals planted recently should be fed on a monthly basis throughout the spring and summer.
Fertilize warm-season grasses such as St. Augustine, zoysia, Bermuda and centipede. Stop fertilizing cool-season grasses such as fescue and bluegrass to prevent heat damage.
Many summer-blooming tropical plants such as hibiscus and mandevilla bloom on new growth. Fertilize to encourage more growth and flowers.
Climbing hybrid tea roses may be pruned as soon as they complete flowering.
Cut spring bulb foliage after it browns or at least begins to yellow - never before. Also don’t tie or braid foliage. Green leaves are needed to manufacture sugars the bulb needs to store and use for next year’s flowering. It’s OK, however, to remove spent flower stalks as soon as the blooms are done.
If needed, prune early spring-flowering trees and shrubs such as azalea, forsythia and dogwood within about 4 weeks after flowers fade. If you delay this task much longer, you run the risk of pruning off next year’s flowers.
Pinch chrysanthemums and certain annuals such as impatiens and petunias to keep them compact and well branched.
Prune roses to open the plant to good air circulation. Pick up diseased leaves.
Remove any reverted green shoots on variegated (leaves with two colors) evergreens to prevent them reverting to a single color.
Take cuttings from houseplants to increase collection or share. Root cuttings in media such as vermiculite, perlite or potting soil.
Thin peaches, plums, pears and apples to about 6 inches apart.
Prune back any damage from winter, but check for nesting birds first.
Lightly prune evergreens, making sure not to cut back to bare branches.
Remove any sucker growths from fruit trees as soon as they appear.
Pines and other conifers can be kept to a compact size by pinching off the new growth "candles."
Collect rainwater for irrigation.
Make sure lawns and gardens receive an inch of water per week. Hand water new transplants until they become established.
Water your lawn in the morning to discourage fungus diseases.
Keep pots and hanging baskets well watered. On very warm days, you may need to water daily.
Always follow label instructions on approved pesticides.
Check new tender growth on your plants for aphids. A few can be tolerated, but large numbers should be controlled. Washing them off with a strong spray of water may be all that is necessary for adequate control. If more is needed, use appropriate pesticide.
Monitor and control snails, slugs and aphids.
Watch out for the "10 most wanted culprits": Mexican bean beetle, Colorado potato beetle, bean leaf beetle, Harlequin cabbage bug, blister beetle, cabbage worm, tomato hornworm, tomato fruit worm (and corn earworm), cucumber beetle and squash bug. Early discovery makes possible early control.
When caterpillars attack live oak trees en masse, it is very alarming, but usually nothing can be done. A healthy live oak will usually regrow its leaves and resume normal activities.
Hoe regularly between rows on hot days to make sure the weeds dry up and die.
The first flowers you’ll see will be your weeds. Work to eliminate the weeds (roots and all), before they have a chance to go to seed, or you will be fighting them for years to come!
Continue to spray rose varieties susceptible to black spot, using a spray recommended for fungus control every 7 to 10 days. Many of the old garden roses and some of the newer ones, especially the Knock Out series, have considerable resistance to black spot.
If moss is a problem in your lawn, choose a combined fertilizer and moss killer when feeding.
Soil purchased for use in beds, low areas and containers should be examined closely. Often, nutgrass and other weeds, nematodes and soil-borne disease are brought into the yard through contaminated soil sources.
Start weeding early in the flower garden. Early competition with small plants can delay flowering. Mulch will discourage weed growth and make those present easier to pull.
Before you pull your hair out, there are herbicides available that help control nutgrass (nutsedge) in lawns. Check with your local Co-op store for more details.
Use a pressure washer or algaecide to remove algae from paths.
Take photos of blooming plants you enjoy and put them in your garden journal so you’ll know what to buy for your own garden!
Visit a specialty plant nursery and explore the many varieties of plants available.
Soon, those tomato plants will start to sprawl all over your garden. Stake or cage them now while they are still a manageable size.
Give your clay and plastic pots a boost on sunny patios. Elevate pots onto boards to lessen the damaging effects on plants from heat radiated off the hot concrete.
For maximum flavor, don’t let zucchini get more than 8-10 inches long.
Promptly remove spent flowers from any plant unless your intent is to harvest the seeds. It consumes the plant’s energy to produce the seeds, and in many species of plants (especially annuals), removing the dead flowers will promote further blooms.
The compost pile should be getting a lot of use these days, both in utilizing this prime garden resource, and adding fresh garden refuse to it. The compost pile should be kept damp. Frequent turning will make your garden waste into plant food much faster.
Check houseplants for signs of being root bound.
Don’t be too quick to give up on tender perennials and tubers such as datura, Mexican bush sage (Salvia leucantha), cannas and dahlias. You still may see new leaves by the end of the month.
Mow lawns weekly.
Open greenhouse vents and doors on warm days.
Clean out pond filters.
Harvest spring-planted crops such as lettuces, spinach and peas.
If the weather is dry, you can treat fences, sheds, etc. with wood preservative and stain.
Many flower or vegetable seeds left over after planting the garden can be saved for the next season by closing the packets with tape or paper clips and storing in a sealed glass jar in your refrigerator.
Move houseplants to a shady location outdoors. The soil in the pots will dry out faster outdoors, so check it frequently.
Pole beans cling to the trellis or sticks more readily if attached by the time they start running.
Pond fish will need feeding … a little and often is best.
Put supports in place now for tall herbaceous plants or those with heavy blooms before they are too tall.
Repair pergolas, arbors and arches as necessary.
The soil has warmed and dried enough now that adding a layer of wood or bark mulch won’t encourage lingering cold wetness.
Remember, birds are still nesting. Keep the feeder full!