June Gardening Calendar

June weather is like that of May but warmer. The long, sunny days are near-perfect for gardening , and fog rolls in each evening to cool our coastal gardens. Little or no rain is expected, and watering demands top priority until rains start again in November. Moisture-loving perennials such as ferns, Japanese iris and astilbe need lots of water. If you are going on a vacation, do not wait until the last minute to give the garden a thorough watering. Potted plants will need the care of a cooperative friend or neighbor during your absence.

You may want to consider some of the drought-resistant plants to reduce watering shores and insure more carefree summers in future years. Many of the gray-foliaged plants add a soft, pleasing texture to dry, sun-baked areas. Some of these are wooly thyme, Stachys lanata, snow-in-summer, pinks, dwarf rosemary, sedums, santolina and dusty miller. Taller perennials for dry soils include the globe thistle, showy sedum, oriental poppy, coreopsis and yucca. Annuals such as California poppy, rose-moss (portulaca), and verbena supply summer color with a minimum of watering. Shrubs that are undemanding of moisture are mugho pine, cotoneasters, sumac, pyracantha, hypericums, manzanita, Choisia ternata, barberry, broom and juniper.

Remove faded flowers from annuals to prevent seed formation. Cut plenty of sweet peas for arrangements; if allowed to set seed, these soon stop flowering. Chrysanthemums need to be pinched, disbudded, and fertilized with ammonium sulfate every 2 weeks until the buds show color.

This is the season to change plantings of bloomed-out winter annuals (such as stock, nemesia, Iceland poppy and calendula) for warm-weather flowers.

Fertilize plants frequently, both those in containers and those in the garden, since constant irrigation leaches nutrients from the soil. Fuchsias, begonias, dahlias, chrysanthemums, roses and all annuals need a monthly feeding. Most of them, during this fast-growing period, benefit from a fertilizer relatively high in nitrogen such as a 10-10-10 (10% nitrogen, 10% phosphorus, 10% potash). If quickly soluble material is used, it is better to fertilize lightly every two weeks than heavily once a month. Slow-release chemical nutrients and the plastic-coated nutrients are more expensive to use, but the nourish a plant from 60 to 90 days without leaching. They are especially worthwhile for plants in containers.

Pruning is needed to cut back spring-flowering shrubs after they have bloomed. Then fertilize and water deeply.

Camellias and azaleas have finished blooming. Remove any lingering buds and flowers. Clean the soil carefully beneath the plants to prevent petal blight. Fertilize by watering in a dry fertilizer, or using a liquid fertilizer such as fish emulsion. Do not dig in dry fertilizer since roots are right on the surface. Add or replace mulch to save moisture and keep the roots cool.

Roses should be fertilized every 30 days until September 1. They need 5 to six gallons of water per plant about once a week. If your soil is sandy, more frequent irrigation will be needed. Dust or spray their foliage regularly.

Bearded iris clumps that have become so crowded that they bloom poorly should be lifted and divided. This is also the month to dig and replant crowded clumps of daffodils and primroses.

Lawns should be fertilized every 30 days to stimulate steady growth and rich green color. Lawns need thorough, deep watering, rather than light sprinkling. Set your mower to cut at a 2 to 2 1/2-inch height.

Make final plantings of dahlias, gladiolus, beans, corn, cucumbers and squash. Winter vegetables, such as cabbage, broccoli and turnips, should go in now.

The patio season begins this month. Dress up the area with plants in containers, either flowering or foliage types.

Sun angles for June

June sun passage, click to enlargeEnlarge image

During June, at a latitude of 40° north and at solar noon, a board fence six and a half feet high will cast a shadow that is a bit over two feet long to the north. At solar noon the sun's altitude (elevation) will peak approximately three-quarters of the way up the southern sky.