Before planting perennials dig a hole about twice the width of the root ball and build a cone of soil in the center. Set the loosened roots atop the cone, then refill the hole. Make sure that you bury all of the roots to just below where new foliage will emerge..
Early in the month, sow in the garden seeds of cool-season veggies such as carrots, chard, and spinach. Later in the month, you can sow seeds of warm-season crops such as beans, corn, and squash. You can also set out seedlings of eggplant, peppers, and tomatoes.
In addition, it’s not too late to plant drought-tolerant shrubs like Rosemary, Ceanothus, Fremontodendron, and Manzanita. Dig planting holes the same depth as the rootball and at least twice as wide. Unless your soil is extremely sandy, it’s usually better to plant in soil that has not been amended. After planting, add a 2- to 3-inch layer of mulch around the plants, keeping it about an inch away from trunks and stems.
You can now start planting tomatoes. Due to their rich flavor, heirloom tomatoes such as ‘Brandywine’ are becoming more widely available as seedlings and plant stock in nurseries. If you can’t find the tomato variety you’re looking for, go to Laurel’s Heirloom Tomato Plants for seedlings of 200 heirloom varieties. For cooler coastal areas such as San Francisco, she suggests ‘Carmello’, ‘Goose Creek’, and ‘Sunset’s Red Horizon’. For warmer regions of the Bay Area and Sacramento, you might consider ‘Eva Purple Ball’ and ‘Paul Robeson’. You can also check out this Sunset Magazine video for tips on how to grow tomatoes.
All Citrus can be planted this month. Don Dillon, owner of Four Winds Growers, suggests the new seedless mandarin ‘Gold Nugget’ for warm-summer areas. Coastal gardeners might try fragrant fingered citron (‘Buddha’s Hand’), which makes delicious candied fruit.
Once all chance of frost has passed, plant seeds or seedlings of summer annuals such as easy-to-grow cosmos, nasturtiums, sunflowers, and zinnias.
After azaleas, camellias, and rhododendrons finish blooming, remove spent blooms. Be sure not to damage the new growth just beneath them. Now is a good time to feed the plants with a fertilizer especially developed for acid lovers.
As you groom your garden, add trimmings to the compost pile along with fruit and vegetable waste. Chop or shred plant materials into smaller pieces to help the plant material break down faster. Alternate 6-inch layers of brown material (dry leaves, straw, and tree cuttings) with 6-inch layers of green matter (fresh lawn clippings and weeds. Be sure to remove seed heads first). Keep the pile as damp and turn it frequently, and voila, you will have rich compost at your fingertips.
Be sure to increase the frequency of irrigation as temperatures rise. Deep-water established plants often enough to prevent wilt and promote deep rooting. But don’t water more than necessary (check soil moisture around roots with a soil auger or by digging down with a trowel). Given that we are still experience water shortages you might consider plants that can tolerate less water.
Eliminate mosquito breeding sites by draining excess water from pipes, gutters, buckets, plant containers, and anywhere else that water may stand or collect.