The signals of springtime

At the start of each month, this column will provide local advice on the activities and chores you should be performing in your garden. Just as important, we will offer a few tips about what not to do during the month.

What better month to start than April? The advice will be especially useful for gardeners from Huntington Beach to Newport Coast, with our unique climate and soils. We hope the tips help bring you success.

Several forces are combining this month to tell plants what to do.

Days are growing longer, and your plants are getting two more minutes of daylight every day. Along the coast, daytime temperatures are two degrees warmer than last month, and soil temperatures are almost two degrees higher as well. These are the unbendable signals from nature that tell your plants when to grow, flower, set seed, drop leaves or go dormant.

Unfortunately, your plants are rather indifferent to your personal wishes for flowers or growth or just about anything else. Different groups of plants respond quite differently to exactly the same signals. As you learn how plants in your garden are preprogrammed to respond to these forces, you will struggle less and enjoy your garden more.

During April, many cool-season annual flowers, vegetables and herbs are putting forth their final glorious burst of bloom before time runs out on them. Pansies, violas, primrose, snapdragons, stock, sweet peas and most poppies are in bloom. However, the longer days are taking their toll on cabbage, kale, broccoli, cauliflower, lettuce and arugula, telling them to hurry up and flower. It’s not a great time to plant cool-season annuals.

For another group of plants, the warm-season annuals, the lengthening days and warming temperatures make this their best planting month. Now is the time to plant petunias, dahlias, verbena, lobelia, zinnias, impatiens, begonia and coleus. Edibles planted now include tomatoes, peppers, squash, beans, eggplant and cucumber. April is the first month to tuck in a few varieties of culinary basils, including sweet, lemon and cinnamon basil.

Fertilizing is essential to these warm-season plants, as they burst forth with new leaves, buds, blooms and fruits. The heaviest, almost glutinous feeders in our gardens are roses, citrus, fruit trees, clematis, fuchsias and hydrangeas. Feed them all. Azaleas, camellias, gardenias and most ferns prefer an acid fertilizer; cottonseed meal works especially well in sandy or clay coastal soils. Gardenias and citrus need additional iron, and this is the time to give them a good dose. Iron won’t work when applied to the cool soils of winter, but it will now.

Most other plants also need nutrition now, and this is one of your most important chores this month. A notable exception, however, is our native plants. These are generally cool-season plants, growing and flowering in a perfect concert to our wet-winter, dry-summer, Mediterranean climate. Do not fertilize or plant California native plants during spring or summer.

For most plants in the ground, we recommend blends of organic fertilizers rather than liquid, water-soluble or synthetics. Organic-based fertilizers contribute to a healthy living soil and gently release their nutrients over a long period. Organic nutrients also contribute less to groundwater pollution, coastal runoff and nitrification of our wetlands.

Roses are displaying their biggest and best blooms of the year. Don’t worry too much about a few aphids ? just hose them off. But do pay attention to the first signs of diseases like powdery mildew or rust. Rather than reach for the chemicals, exchange susceptible varieties for those with better disease resistance. Cultural adjustments, such as improved the air circulation around the plant, will improve the situation dramatically.

This may be the best month of the year for planting avocadoes, blueberries, citrus, clematis, wisteria and turf grass. Thin the nickel-sized fruit of peaches, nectarines and apricots to one every 4 to 6 inches. Do not prune hydrangeas now or you will be without flowers all summer. Stake tall perennials like delphinium, foxglove, lilies and dahlias to prevent breakage. Apply a fresh 2- to 3-inch layer of organic mulch over exposed soil between trees, shrubs and perennials.

Especially in April, take your gloves off for a moment, stand back and enjoy the marvels of nature in your garden.