As the days lengthen and the sun gets higher and hotter, watering becomes more important. It's warm enough in April to plant tomatoes, peppers, marigolds and other plants that shine in summer.
Help roses repeat The April bloom on roses is spectacular — usually the best of the year — and roses will keep blooming every six weeks or so if the spent flowers are promptly cut off and the plants fed. Make the cuts right above an outward-facing leaf, far enough down on the stem to ensure strong new sprouts. Don't just cut off the flower. Make the cut just above what's called a "five-part leaf" — a leaf divided into five leaflets. Use a rose fertilizer and lightly cultivate it into the soil.
Citrus season This month is the best time to plant any kind of citrus. During their stay at the growers, potted citrus are watered and fertilized often, so lightly fertilize every couple of weeks and don't let new plants dry out, gradually watering and fertilizing less as plants become established in the garden. Make an earthen dam about 4 inches tall with a diameter a little wider than the root ball. Fill it twice each time you water. Mature citrus often need little or no fertilizer and infrequent irrigations, but for this to work, fallen leaves must remain on the ground as mulch.
Tomato time It's usually warm enough in most areas to plant the so-called main crop tomatoes — all the heirlooms, 'Big Boys' and beefsteaks. Close to the beach, May is a better month, unless you plant a variety that can take cooler weather such as 'Early Girl' or 'Stupice,' a Czech heirloom. When choosing any variety, look for the letters VFN, which indicate verticillium and fusarium wilt and nematode resistance, if you've had problems in the past. Bury tomato transplants so soil covers the stems up to the first set of compound leaves, pinching off any lower ones.
This sounds radical because planting other things even a teeny bit too deep is the quickest way to kill them, but tomatoes will root all along the buried stem.
Eat your vegetables Since we're all supposed to be eating more vegetables, plant something other than tomatoes, such as beans, corn, cucumbers, leaf lettuce and other salad greens, plus melons, peppers, pumpkins, squash, sunflowers and tomatillos. And plant some basil or cilantro to go with those tomatoes.
Bougainvillea bullies If your bougainvillea threatens to take over your arbor or fence, now is the time to get it under control. Put on thick gloves to guard against the thorns, and grab the long-handle pruning shears and whack it back. The plants will quickly recover in the warming weather.
It's also a good time to plant bougainvillea, but investigate any variety you are considering to see if it grows well in your particular microclimate. Also look into some of the smaller kinds that have become available in the last few years and may need less attention.
Bulbs bow out Many spring bulbs probably have finished blooming, and though conventional advice is to leave the browning foliage, experienced gardeners have discovered it's not necessary, except with daffodils. Let foliage completely brown on daffodils, but on other bulbs cut it off with scissors as it becomes untidy. Don't yank it off or you'll uproot shallow bulbs and damage those that are planted deeper. There is no need to dig up and store bulbs in Southern California, but some, including most daffodils and Cape bulbs such as babiana and freesias, should be kept on the dry side in garden beds. Dig up and throw out tulips because only their leaves will return next year.
Summer flowers Though it's possible to plant them in May, summer's flashy annuals and bedding plants can go in as soon as spring's annuals have faded. Try ageratum, celosia, bedding dahlia, gloriosa daisy, marigold, petunia, portulaca, verbena and zinnia. In the shade, try bedding begonias, browallia, caladiums, coleus, impatiens, mimulus and forget-me-nots.
There are lots of perennials in bloom at nurseries right now and some will be in bloom this summer as well, so they're a good bet to plant now. Look for summer-flowering agapanthus, bidens, coreopsis, daylily, gaillardia, heliotrope, lion's tail (Leonotis), penstemon, salvia, Shasta daisy, tulbaghia, Verbena bonariensis and V. rigida, and yarrow. There are even some that bloom in fall, including asters, helianthus, Japanese anemone and Mexican marigold (Tagetes lucida).
Sow or sod lawns Kids, dogs and lack of water can leave bald spots in lawns, and this month is the perfect time to try a patch or repair. Cut out the old sod and splice in new sod from a nursery, or cultivate the soil and sow seeds. Keep seed or sod moist until it becomes established. It's also the ideal time to seed or sod entire lawns. If you over-seeded Bermuda lawns last fall for winter green, it's time to start mowing lower ( 1/2 to 1 inch) to encourage the shorter Bermuda to green up for the summer ahead.