What your Sonoma County garden needs in May

By now, spring rains will have subsided and the temps will be warming up. It’s the time we gardeners have all been waiting for — planting! Veggie starts and flowering annual and perennial plants should be readily available in nurseries and garden centers.

But before we start digging, we should take time to troubleshoot our irrigation systems for cracks, leaks and clogs. Dirty filters can wreak havoc, especially if you are on a well. Clean out filters and replace them as needed. Flush out drip systems and make sure all emitters are working. Replace batteries on systems that use battery-operated controllers. As we start to irrigate, practice water conservation by watering in early morning or evening only and, ideally, using drip irrigation.

Food gardening

In the veggie garden it’s time to plant beans, cucumbers, eggplant, kale, lettuce, melons, peppers, squash and tomatoes. Always plan to grow veggies your family likes to eat and share any excess with friends and neighbors.

Add edible flowers to your garden for a pop of color and to attract beneficial insects that pollinate the garden and provide an ecological balance against harmful pests. Common edible flowers include carnations, violas, lilacs, roses, lavender, marigolds and nasturtiums. You can also enjoy the flowers of herbs such as rosemary, basil, thyme and sage.

If you don’t have a dedicated vegetable garden, consider planting a few veggies in the ornamental garden. Leafy greens, in particular, make attractive additions to beds and borders.

Acclimate transplants started indoors before planting them in garden beds. Harden off transplants by setting pots outdoors during the day and moving them indoors at night for a few days before leaving them outdoors for several more days. Tender seedlings may succumb to drastic changes.

If you buy warm-weather veggie transplants, don’t buy a plant forming fruit — it’s been in the container too long. Tomatoes and peppers should be wider than they are tall.

Check not only for healthy green foliage, but also make sure that roots are healthy and not matted by gently easing the plant out of the container to verify. Consider choosing varieties with fewer days to maturity and production and labeled “drought-resistant” or “drought-tolerant” in the description.

Best choices are California-bred plants suitable for our climate. Look for determinant tomatoes that save water since the fruit matures about the same time. For a list of drought-resistant crops and varieties to help in making selections, visit ucanr.edu/sites/scmg/files/183771.pdf

Overly vigorous fruit trees, trees that are too large, or fruit trees that were not sufficiently pruned because of the wet winter, may be summer pruned from the end of May into June or July.

Pruning reduces the production of fruit, but less fruit requires less water. Cherries and most peaches can be pruned after the fruit is harvested. At a minimum, remove upright waterspouts emerging from branches and suckers emerging from the tree roots or base. These thin branchlets do not flower or fruit and they compete for water and nutrients.

Most, but not all, fruit trees benefit from fruit thinning; a favorable fruit-to-leaf ratio promotes large fruit. In general, space fruit every 4-6 inches along a branch or leave one fruit per spur; but leave the largest fruit even if unevenly spaced. Remove small and damaged fruit.

Weeds are competing with crops for sun, water and nutrients, so continue to pull them out. Plus, weeds can harbor some nasty food garden pests. Also continue to compost and mulch. Both will enhance retention of soil moisture along with other benefits. Some crops, such as tomatoes and corn, are heavy feeders and will benefit from 2-4 inches of compost.

Don’t over-compost or add additional fertilizer high in nitrogen. It will only cause a flush of green growth requiring extra water, in addition to attracting pests.

If about half of the tops of the garlic bulbs planted last fall have died back or are falling over, it’s time to harvest. To avoid cracking the garlic open, lift or dig bulbs out of the soil rather than pulling them. Brush off soil and allow bulbs to dry outdoors in sun for two to three weeks until skins become papery. Gently clean the cured bulbs with a soft bristle brush taking care not to strip off the papery skin, and cut off roots to about 1 inch. Store in a cool, dark, dry place.

Add ornamentals for beauty, bug control

May is not too late to plant summer blooming bulbs such as dahlias, crocosmia, gladiolas and summer annual flowers like begonias, marigolds, Gerbera daisies and sunflowers.

When planting and transplanting, watch sun exposure and heat. When transplanting young plants into direct sun, provide some shade. Positioning lightweight lawn furniture is an easy solution for creating shade until plants become accustomed to their new location.

Any major planting or transplanting projects should be postponed until fall and the onset of the rainy season, because new plants struggle and often fail in summer heat.

Deadhead and prune azaleas, rhododendrons and camellias after they have finished blooming. To remove the spent flowers of the rhododendrons, use clippers or two fingers to nip just above the two new leaflets. During the spring and summer, feed these shrubs monthly with a balanced organic fertilizer formulated for acid-loving plants.

Prune all spring-flowering trees and shrubs when bloom is past. Tidy up the spent wildflowers you planted last fall. Rather than pulling them all up, you may want to let some go to seed. You can collect the seeds for planting next fall and they will attract a wide array of seed-eating birds to your garden.

Watch out for aphids

Depending on the weather and how much nitrogen fertilizer you may have applied, May can see some heavy infestations of aphids. Use a spray of water to remove aphids; most often, they can’t find their way back up the plant.

Soap sprays can be used, but the infestations must be thoroughly covered, and repeat applications may be necessary. Aphids flourish with tender new growth in the warming weather, so management can be an ongoing process.

Contributors to this week’s column were Diane Judd and Debbie Westrick. The UC Master Gardener Program of Sonoma County sonomamg.ucanr.edu provides environmentally sustainable, science-based horticultural information to Sonoma County home gardeners. Send your gardening questions to scmgpd@gmail.com. You will receive answers to your questions either in this newspaper or from our Information Desk. You can contact the Information Desk directly at 707-565-2608 or mgsonoma@ucanr.edu.