When temperatures rise, garden maintenance slows but never ceases entirely. Summer tasks include strategic weed control, careful watering, selective pruning, seed harvesting, and more. And summer is the perfect time to imagine possibilities for your native plant paradise: Remember: Summer planning, fall planting.
Though fall is the best time for planting, some natives don’t mind being installed and watered when it’s warm. Try these riparian (river- and creek-side) species: Aquilegia formosa (western columbine), Erythranthe cardinalis (scarlet monkey flower), Juncus spp. (rush), and Sisyrinchium californicum (yellow-eyed grass). Or these desert jewels: Abutilon pameri (Indian mallow), Calliandra spp. (fairy duster), Chilopsis linearis var. linearis (desert willow, including the cultivar ‘Burgundy’), Justicia californica (chuparosa), and Sphaeralcea ambigua (apricot mallow).
Most grasses and ferns can also be planted now. Our nursery sales associates can provide other suggestions for summer planting.
Two iconic Californians, Ceanothus (California lilac) and Arctostaphylos (manzanita), are best planted in the fall, as they are especially prone to disease when watered in summer.
Try these flowering perennials from seed: Achillea millefolium (common yarrow) Baileya multiradiata (desert marigold), Eriophyllum confertiflora (golden yarrow) and Asclepias spp. (milkweeds, for monarch butterflies). Sow warm-season grasses (e.g. Aristida, Agrostis, Bouteloua, Sporobolus). Keep just-sown seed moist but not soggy.
Hand pull or hoe down annual invaders when they’re small and before they flower and set and distribute seed. Dig deeply to remove deep-rooted dandelion, filaree and other perennial weeds.
This non-chemical means of pest management uses the sun’s rays to control weeds, plant pathogens and other soil-borne pests. Over the summer, inland gardeners can solarize their soil by clearing and leveling an area, watering it deeply and covering it very tightly with clear plastic for four to six weeks. (This technique is less effective along the coast). Learn more.
When a heat wave is imminent, water BEFORE temperatures rise. Irrigation should be slow and deep – never a little bit. Established drought-tolerant plants appreciate a thorough soak every 2-3 weeks during the warm months. Exceptions: Fremontodendron (flannel bush), Trichostema lanatum (woolly blue curls), and most native bulbs. They prefer bone-dry soil over the summer.
New transplants require regular irrigation for one or more years, until they’re established. Check soil moisture frequently and water when the top 3”-4” are dry. Always check the original root ball and surrounding native soil (the original root ball may dry out first). To encourage plant health and deep extensive roots, water deeply–never a little bit. .
A 3”-4” layer of mulch insulates plant roots (especially important during summer); discourages weeds; helps retains soil moisture; and beauties the garden. Use either organic matter (leaves, bark, wood fibers – freshly chipped materials are okay) or inorganic (decorative rocks or gravel). Both new and established gardens need mulch between plants all year, every year.
Habitat Gardeners: Leave several meter-wide, sunny patches of soil bare, to invite highly beneficial, ground-nesting native bees and wasps.
Protect container-grown plants and their roots from summer heat by clustering several pots together or double-potting (slipping smaller pots into larger ones for added insulation). Add a top dressing of decorative rock or wood chips to help conserve soil moisture. Check soil frequently and water as needed, that is, more often during periods of warm or windy weather. Always soak thoroughly, until water drains from the holes. Empty water from saucers ASAP, if used.
Come late summer, cut sages back by one-third to one-half to encourage compact growth. Cut leggy Encelia californica (bush sunflower) back to 6” stubs for tighter habit and another round of color in the fall. Shear cool-season grasses (e.g. Aristida, Melica, Stipa) to just a few inches above the crown; they will regrow come autumn.
Gather home-grown native plant seed when fruiting bodies are brown and dry (and birds have had their fill). Place harvested material upside-down in paper bags (not plastic), so that seed may fall to the bottom of the bag, and allow to dry completely at moderate temperatures. After a couple weeks, seed remaining in the fruits may be extracted by hand or by gently threshing or crushing the dried plant material. Store in an airtight jar until fall sowing. For more information on collecting seed in the garden, check out The Complete Guide to Saving Seeds by Robert E. Gough and Cheryl Moore-Gough, available for purchase in the TPF bookstore!