Dig In: Garden checklist for week of April 27

Our last weekend in April will be decidedly damp, but not necessarily wet.

According to the National Weather Service, Sacramento has a 50-50 chance of thunderstorms and occasional showers through Sunday morning. Then we start to warm up in a hurry.

That splash-and-dash rain won’t add up to much, says the weather service, which estimates Sacramento’s total precipitation from these weekend storms at under 0.1 inch.

After a weekend in the low 60s, our temperatures jump back up to the 80s, peaking at 86 degrees on Wednesday. That’s quite a swing from well below normal to well above; average high for Sacramento this week is 74 degrees.

Unfortunately, that combination of dampness followed by warmth creates the perfect condition for fungal disease. Be on the lookout for powdery mildew, rust and black spot. Clip off infected leaves and dispose of them in the garbage (not the compost pile).

Meanwhile, nights will remain relatively warm with lows in the mid 50s. That’s good news for tomato gardeners as soil continues to warm.

Once the clouds clear, get to work. Spring growth is in high gear.

* Set out tomato, pepper and eggplant transplants.

* From seed, plant beans, beets, cantaloupes, carrots, corn, cucumbers, melons, pumpkins, radishes and squash. Plant onion sets.

* In the flower garden, plant seeds for asters, cosmos, celosia, marigolds, salvia, sunflowers and zinnias. Transplant petunias, zinnias, geraniums and other summer bloomers.

* Plant perennials and dahlia tubers for summer bloom. Late April is about the last chance to plant summer bulbs, such as gladiolus and tuberous begonias.

* Transplant lettuce and cabbage seedlings.

* Weed, weed, weed! Don’t let unwanted plants go to seed.

* April is the last chance to plant citrus trees such as dwarf orange, lemon and kumquat. These trees also look good in landscaping and provide fresh fruit in winter.

* Feed citrus trees with a low dose of balanced fertilizer (such as 10-10-10) during bloom to help set fruit. Keep an eye out for ants.

* Apply slow-release fertilizer to the lawn.

* Thoroughly clean debris from the bottom of outdoor ponds or fountains.

* Start thinning fruit that’s formed on apple and stone fruit trees — you’ll get larger fruit at harvest (and avoid limb breakage) if some is thinned now. The UC recommendation is to thin fruit when it is about 3/4 of an inch in diameter. Peaches and nectarines should be thinned to about 6 inches apart; smaller fruit such as plums and pluots can be about 4 inches apart. Apricots can be left at 3 inches apart. Apples and pears should be thinned to one fruit per cluster of flowers, 6 to 8 inches apart.

* Azaleas and camellias looking a little yellow? If leaves are turning yellow between the veins, give them a boost with chelated iron.

* Trim dead flowers but not leaves from spring-flowering bulbs such as daffodils and tulips. Those leaves gather energy to create next year’s flowers. Also, give the bulbs a fertilizer boost after bloom.

* Pinch chrysanthemums back to 12 inches for fall flowers. Cut old stems to the ground.

* Mulch around plants to conserve moisture and control weeds.