June Gardening Guide

Like April and May, June is a busy gardening month.

Continue planting flowers, but be aware that the hotter it gets, the more stress new transplants will suffer. It’s better to get as much planted as possible by mid-June.

The lawn will grow quickly in June and likely require frequent mowing. Keep the blade high and mulch—don’t bag—the clippings whenever possible. If several days of rain make mulching impossible, catch and dispose of the clippings.

The most important thing starting this month will be to keep everything watered. Get out all the hoses and sprinklers. If you haven’t done so already, examine them for leaks or damage. Buy new ones if necessary. Consider investing in a soaker hose for large areas that need deep watering. You may also think about installing a sprinkler system, if you watering needs are vast.

Make sure mulch levels in flowerbeds and around trees and shrubs are adequate — 2 inches to 4 inches deep — in June to prevent moisture evaporation and to keep the soil temperature cool.

Watch the patio containers and window boxes for dryness. They lose soil moisture much more quickly than flowerbeds. Container plants can die quickly if left to dry out in the hot sun. 

Flowerbeds, even those in shade, and newly planted trees and shrubs, need a good soaking, too, when the summer heat sets in. Watering in the morning, from 7 a.m. to 11 a.m., is optimum. Nighttime watering is not recommended because wet gardens at night tend to draw damaging pests, such as slugs and beetles. However, if any plant is wilting, water it no matter the time of day. Established trees and shrubs don’t need watering as much as shallow rooted annuals and some immature perennials. Having enough mulch helps retain water and keep the soil cool.

Roses are in their glory and need feeding and water. Watch for disease. All flowering plants need consistent feeding during this blooming season. Keep an eye out for pests and disease on annuals and perennials, as well.

Remember these useful, free informational resources.

Now for the tips.

INDOORS

Houseplants

• As we said last month, some indoor plants, such as hardy fern, asparagus fern, dracaena, schefflera, rubber tree and others can be taken outside in June. Ficus, spider plants, airplane plants, African violet and others also will benefit from a summer outdoors.

• Remember to place houseplants in outdoor areas that will supply their light or shade needs. For instance, don’t place a Boston fern in direct sun. It will do well under a shady tree. Not many houseplants will thrive in the direct summer sun. Most prefer a shady or partially shady spot on the patio or under a tree. Don’t forget to water and feed them, too.

• For houseplants that have had a hard winter, outdoor conditions should perk them up and encourage new, stronger growth. Cut back long, leggy stems and trim any weak growth. If it still has healthy roots, the plant will quickly replace these.

• For houseplants that remain indoors for the summer, remember to feed and water them, too. Feed them monthly at full strength during this growing season. As always, be careful not to over-water.

• June is a good time to divide or repot large houseplants. Do it outdoors and avoid an indoor mess. Choose a slightly larger pot than the old one. For transplants, choose a pot that gives enough room for growth, but that doesn’t overwhelm the fledgling plant.

• Southern and southwestern exposure windows will produce great heat and strong light during the summer months. Move houseplants away from hot windows if they need cooler, shadier conditions.

OUTDOORS

June Tips for Lawn Care

• Grass needs a full-strength fertilizer in June. Most weed-and-feed applications contain this. The weed chemicals in this will take care of growing weeds.

• Apply another round of pre-emergent broadleaf weed and crabgrass controls (you did this in March or April). Be careful not to apply too much fertilizer. If you use weed-and-feed, make sure the pre-emergent application does not contain fertilizer, also.

• If you don’t want to water much during the hot, dry summer, then DON’T feed the lawn any more until fall.

• Apply insect controls, for pests such as white grubs and white flies. Use spray or granule applications. Remember that these chemicals can be dangerous to humans and animals, including pets. Don’t apply on windy days and wear protective clothing, including gloves. Read package directions.

• For a lush lawn, mow grass at the highest setting from June through fall—that’s about 3 inches high. Don’t give it a "buzz cut" in June.  Mow as often as needed to keep the lawn neat looking. If you have a mulching mower, use it and don’t bag the clippings. Mulching grass clippings returns nutrients to the soil, plus it helps keep the soil from drying out as the days get longer and hotter. This will help reduce your summer watering.

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Annuals

• Feed bedding and container plants about every two weeks.

• Don’t wait much longer to plant dahlias. They should be in the ground before mid-June; after that it’ll be too late for them to develop and flower properly. Remember to set stakes in the ground when you plant them. This way, you won’t disturb the roots later.

• When large-flowering dahlias are about a foot high, make sure they are securely supported by stakes. Pinch out the terminal (center) bud, after the plant has developed the first three sets of leaves. This will induce branching. When you see terminal buds on the side branches, pinch them, too. Then, let it grow. Dust periodically with pyrethrum to control pests. During hot, dry weather, water dahlias deeply about every ten days. Mulch will help keep down weeds and conserve moisture. Feed dahlias every two weeks with a liquid plant food.

• Keep planting annuals in June, but try to avoid planting in the heat of the day. Plant before 11 a.m. and after 5 p.m. to avoid placing undue stress on the new transplants. After planting, fertilize and water deeply.

• Zinnia and many other outdoor seeds are sprouting in June and need daily watering in hot weather. Feeding also will encourage growth and blooms.

• Placing mulch on top of container plant soil will help retain moisture.

• Petunias, marigolds, shasta daisies and others will benefit from pinching and deadheading. Pinching means removing the growing tips (when branches are 4 to 6 inches long), causing the plants to produce side shoots.  Deadheading means removing spent blooms.

• Remove flower spikes from coleus to prevent leggy growth.

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June Tips for Bulbs

• Remove spent flowers and stems from iris, tulips, narcissus, hyacinth, gladiolus and other flowering bulbs, but allow the leaves to die down naturally.

• Continue planting gladiolas bulbs every two weeks for continuous bloom through late summer and fall.

June Tips for Perennials

• Feed roses with rose food and inspect for insect pests, black leaf and other diseases. Continue feeding roses about every six weeks with a special rose food.

• At mid-June, fertilize blooming perennials.

• Insert stakes to support delphinium, dahlias, gladiolus, lilies, helianthus, hollyhock and other tall plants. Gently tie them to the stakes so they won’t be blown over or broken by wind.  Old pantyhose is great for this. Stakes can be made of anything that will provide support. Purchase them or make them out of fallen limbs, old pipes, etc. 

• Feed clematis and make sure its roots are covered with mulch to keep them cool.

• After peonies have bloomed, continue watering them because they are producing next year’s flower buds at the top of their roots. These buds are the “eyes” that you will transplant in the fall, if you plan to move any peonies. 

• June is the time to start pinching—nipping off the growing tips—of hardy chrysanthemums, which will bloom in the fall. Pinch new growth about every ten days. This causes branching and more flowering. Target pinching for June 1 and 15. (Do it again on July 1 and 15. Don’t pinch after mid-July, which may delay blooming or result in no blooms.)

• Keep chrysanthemums well watered and fed during June and July, which are their prime growing months. They are heavy feeders, so fertilize several times during the summer—but don’t feed after about Sept. 1.

• If you are growing a Christmas poinsettia outdoors now, consider taking cuttings from it to start new plants. This can also be done in July. Place the cutting in water until it forms roots. Then transplant into soil and put outside.

• Watch for volunteer or “rogue” groups of flowers among perennials. Pull out or transplant elsewhere.

• A great many perennials are in bloom during June. Here are some to look for in your garden:

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Dividing and Transplanting

• To divide spring bulbs, such as tulips, jonquils and daffodils, dig after the foliage has died down. Remove the dead leaves and shake off excess soil. Label and store the bulbs in a cool dry place until fall, when they can be reset. This can also be done in May, if the foliage has ripened by then.

• Iris rhizomes can be dug, divided and reset in June, after the blooming season is finished.

• Here are some other perennials and biennials (plants that flower every other year) that can be seeded or divided and transplanted in June:

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Pests and Diseases

• Check evergreens for bagworms in June. Pick off the worm cases and apply controls as needed.

• Check elm trees again in June for “wetwood” disease, a bacterial infection in the heartwood that causes sour-smelling liquid to seep out through wounds in the tree or at a split where two large branches unite. This flow is usually greater in spring and early summer.

• Dust dahlias with pyrethrum in June to discourage chewing and sucking insects.

• Watch columbine for pests such as leaf miner.

• Watch chrysanthemums for insects such as aphids, thrips, leaf miners, red spiders and mites.

• Apply slug bait in damp, shady flower gardens, especially around hostas. You can also try sprinkling broken eggshells on the soil, which slugs hate to crawl over. And salt will kill any that you find. There are also slug traps available. Look in your local garden center. Gardening books have other ideas, as well.

• Check all bedding flowers for bugs and apply controls. Look for chewed leaves, lacy holes in leaves, damaged flower petals, dying or wilting plants.

• Dust zinnias to control red spiders and leaf-eating caterpillars.

• At the end of June, watch for caterpillars feeding on birch and pin oak trees. Spray if needed.

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Pruning

• Clip rapid-growing junipers around foundations, unless they are new plantings from last fall, in which case you want to keep the new growth. Use hedge shears on the tips, hand shears for cutting back and shaping larger branches. Remember to rinse off the cutting implements because evergreens exude a sticky substance when cut. Also, make sure the cutting implements are sharp.

• Prune flowering trees and shrubs after blooming. These include spirea, forsythia, French hydrangea, honeysuckle, mock orange, azalea (rhododendron) and Weigela.

• In pruning lilacs, be careful not to clip off the flower buds at the tips of young stems—these will produce the flowers of next year. Cut off only the old bloom. Do not cut the buds at the base of the bloom.

• Japanese yews may need pruning in June to keep them compact.

• Check before pruning clematis. Pruning depends on the type of clematis and when it flowers. Some types should not be pruned until after they bloom, because the woody growth from last year is what produces flowers this season. However, it’s important to prune clematis, if the plant needs it. Consult a gardening manual or ask an expert about the type you have. Mark the plant after you find out, or make a note in your gardening journal or on your 12-month calendar.

• Wisteria vines can be pruned after spring flowering.

Tools and Equipment

• Take large hedge shears to a hardware store or garden shop to be sharpened. Sometimes, smaller cutting implements, such as hand clippers, also must be professionally sharpened.

• Here's a list of the garden tools people seem to use the most.

• Hand tools. Clean and sharpen blades, if needed. Use sandpaper or a sharpening stone. Some tools, such as small pruning shears, are best if sharpened professionally. Install pegboard for hand tools and heavy hooks to hold spades, pitchforks, brooms, hedge shears and other large tools.

• Hoses. Before throwing out a damaged hose, consider an inexpensive repair kit that will let you remove the hole and splice the two ends back together. Also, check the hose-reel and decide if you need a new one. These get a lot of wear-and-tear. If you don’t have a hose-reel, consider investing in this valuable time and back-saver.

• Sprinklers. Unless you have in-ground sprinklers, you'll be needing these life-savers quickly as the summer heat comes on. There are different kinds for different needs. Some cover large areas, such as lawns, and others are designed to water only small gardens with gentle sprays. Many are quite inexpensive. Also, invest in a watering timer that can be attached to any outdoor faucet.

• Hose-End Sprayers. There are different types for different uses. Some are designed to use granular fertilizers. Others require a liquid solution that mixes with the water running through the hose. Keep the sprayers used for chemical applications separate from the ones used to apply fertilizers. Do not use a pesticide sprayer to apply anything else, and vice versa. Labeling is a good idea.

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Trees and Shrubs

• Tie up climbing roses and cut back dead canes. Feed liberally with rose food. Inspect for insect pests and diseases and treat appropriately. Consult a rose expert or someone at the local garden center who knows about roses.

• You can still transplant new trees and shrubs, but make sure to keep them well watered, and apply mulch around the base to retain moisture.  Stake or add other supports, if needed, to protect against storm winds.

Watering

• Flower gardens need at least 1 inch of rain per week for best growth. If you need to, then water with the hose. Make sure mulch is at least 2 inches deep to retain moisture and control weeds.

• A gardening rule of thumb is: when the thermometer starts hitting 90 degrees consistently, check the needs daily of all plants, especially those in containers and those in flowerbeds that receive direct sunlight.

Birds

• Most birds have finishing flocking and nesting for the spring, but a few stragglers may remain early in June. No need to keep feeding the birds—unless you want to. But remember, bird food will draw squirrels, also.

• Get a birdbath and keep it filled. They can be a lovely statuary addition to the garden. Birds will drink from it and also splash around while taking baths. Fun to watch!

Miscellaneous

• In between all the work, ENJOY YOUR GARDEN. Stop and have a barbecue. Invite some friends over. Light the patio candles. Remember to enjoy the summer!

• Don’t forget to take some photos of your garden at this point. So many things are in bloom in June. Photos will help you remember later what it all looked like, and will help later in your planning for next year.

• If you haven’t started one, get going on a garden journal. Make notes on all the work you’ve done, what was successful, what rainfall amounts there were this year, what questions you have, etc.

• Consult the gardening budget, and see where you stand after all the lawn care, planting and equipment expenses. Adjust likewise, if necessary.

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