Gardening by Month - June

Trees & Shrubs

• Watch for bagworms (Thyridopteryx ephemeraeformis) feeding on plants, especially junipers and arborvitae. Collect and dispose as they are located.

• Fertilize roses as needed after the first round of blooms. Use a fertilizer higher in phosphorous if possible, otherwise, use a balanced fertilizer.

• If wanting to propagate plants, softwood cuttings can be taken from trees and shrubs as the spring's new growth begins to mature.

• Squirrels are making nests now and dropping leafed twigs. The remains of their feeding on horned oak galls may also be observed. 

• Trees and shrubs may still be fertilized as needed before July 4th.

• Any pruning of spring-flowering trees and shrubs should be completed before the end of June to encourage as many blooms as possible in the following year. Pruning too late can result in cutting off the next year's blooms.

• Continue spraying roses with a fungicide as needed to help prevent black spot (Diplocarpon rosae) disease.

• Rose slug (Hymenoptera) damage may be noticeable. Treatment is not required as the damage is primarily aesthetic.

• Japanese beetles (Popillia japonica) are usually active at this time. Pheromone traps may attract more beetles than they can trap, causing damage to be worse. A more practical control method is to hand-collect adults early in the morning when the insects are still sluggish and deposit them in soapy water.

• Bottlebrush buckeyes and St. John's wort are in bloom this month. 

• Lace bug (Hemiptera) damage may be noticeable on azaleas and other plants. The damage appears as bronzing or stippling on the upper side of the leaves, with the insects being noticeable on the underside of the leaves. Lacebugs can be dislodged using a strong stream of water.

• Rose rosette (Emaravirus sp.) is most readily transmittable in May-July on new active growth. Nothing except removal can be done for the plant. 

• Apply a second spray for borer control on hardwood trees where needed.

• Leafcutter bees may be causing damage to plants, however, no control is needed as these native bees rarely cause actual harm. 

Annuals & Perennials

• Deadhead bulbs and spring flowering perennials as blossoms fade.

• Plant tropical water lilies when water temperatures rise above 70^oF. 

• Aster yellow may start showing symptoms this month. Nothing can be done to save infected plants, so remove and discard any infected plants.

• Daylilies are in peak bloom this month.

• During times of high humidity and cooler nights, powdery mildew may be prevalent, especially on phlox and peonies. Preventative fungicides, encouraging good airflow, and pruning out badly infected parts, are all useful control methods. 

• Keep an eye out for clematis wilt, vinca stem canker, and peony blotch.

Lawn

• Water turf as needed to prevent drought stress.

• Mow lawns frequently enough to remove no more than 1/3 of the total height when mowing. There is no need to remove clippings unless they become excessive.

• Gradually increase the mowing height of zoysia lawns throughout the summer. By September the mowing height should be 2-2.5 inches. 

• Mow bluegrass at 2-3.5 inch height. Turfgrasses growing in shade should be mowed at the higher recommendations. 

• Zoysia can be fertilized now while actively growing. Do not exceed 2-3 lb of nitrogen fertilizer per 1,000 sqft per year.

• Dethatch zoysia lawns as new growth begins to keep the lawn vigorous and reduce disease problems. Cool-season lawns should not receive fertilizer until fall. 

Fruits & Vegetables

• Peach moths (Grapholita molesta) emerge this month. They are most serious on peaches where the first generation attacks growing tips. Wilted shoots should be pruned out.

• Thin overloaded fruit trees to receive larger and healthier fruits come harvest time. Thinned fruits should be a hands-width apart.

• Strawberries are ready for harvest. After harvesting: thin excess plants, remove weeds, fertilize if needed, and apply mulch.

• Renovate strawberries after harvest. Mow the rows; thin out excess plants; remove weeds; fertilize and apply a mulch for weed control.

• Summer fruiting raspberries are ripening now.

• Begin control for apple maggot flies (Diptera). The best control is preventing females from laying eggs by hanging red-painted balls coated with tanglefoot, or another sticky substance. 

• Spray peach tree trunks and other stone fruits for peach tree borers (Synanthedon exitiosa). 

• Prune and train young fruit trees to eliminate poorly positioned branches and establish proper crotch angles.

• Cucurbits, tomatoes, and peppers may have pollination issues during times of high heat. Tomatoes and peppers cannot set fruit when temperatures exceed 90^oF. During high humidity, cucurbit pollen becomes sticky and does not transfer well. 

• Flea beetles (Coleoptera) may be found on eggplants and other plants.

• Warm-season vegetables that can still be planted through June include basil, beans, cucumbers, edamame, eggplants, melons, okra, peppers, summer squash, sweet potatoes, and tomatoes. 

• As cucumber and squash plants begin to vine, keep an eye out for cucumber beetles (Coleoptera) and squash bugs (Anasa tristis), squash vine borer (Melittia cucurbitae) adults emerge this month and lay eggs on the lower part of the stem.

• If mature enough, stop harvesting asparagus when the spears become thin. The plants can be fertilized after the last harvest with nitrogen. Apply .10 lbs of a balanced fertilizer per 100 sqft. 

• Treat corn earworms (Lepidoptera) by applying a couple of drops of mineral oil to the base of the silk as they appear. BT spray will also work while the silks are young, however, once the earworm is in the ear, it becomes ineffective.

Miscellaneous

• Thin seedlings as needed before plants start to crown each other.

• Apply organic mulches as the soil warms. This will conserve moisture, help with weed control, and enrich the soil as the mulch decays. 

• Soaker hoses and drip irrigation systems make the most efficient use of water during dry times. Be sure to water early in the day and avoid overhead watering to allow foliage to dry before nightfall to minimize fungal diseases.

• Be sure to keep an eye out on plants for any scorch, sunburn, or heat stress in times of high heat.

• Scout for damage from thrips (Hemiptera) and leafhoppers (Thysanoptera). Leafhoppers usually do not require any control, however, insecticidal spray can be used on both pests (only works on young leafhoppers). 

• Galls may be noticeable on various plants such as oaks, hackberry, and witch hazel. Galls are a normal part of plants and usually do not harm plants. Eriophyid mites are commonly responsible for these galls and do not require any control.