gardening on sand 2009a

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This lecture was given in August, 2009 as part of the California native plant gardening series ‘Out of the Wilds and Into Your Garden’


  • 1. Out of the Wilds and Into Your GardenGardening with Western L.A. County Native Plants Project SOUND - 2009 Project SOUND

2. Gardening on Sand August 1st & 4th 2009 Project SOUND 3. Our mission: to make this garden more water-wise Project SOUND 4. What is a sandy soil? Soil: a combination of sand,silt, clay, minerals andorganic matter that alsocontains some air and water. Clay soils are sometimesreferred to as heavy soilsand sandy soils are called Sandy soils contain highproportions (60% or more)of larger (sand) particles.Many sandy soils areactually sandy loams wonderful garden soils Project SOUND 5. Tests for sandy soil: sedimentation test Fill a quart jar 2/3 full withwater Add dry soil (break up clods)until water is within 1 of topof jar. Put the lid on the jar andshake it energetically untileverything is swirling around.Then set it aside and let itsettle, and mark layers untilthe water clears. The layers indicate just howmuch sand, silt and clay makeup your soil. Project SOUND 6. The sedimentation Sand Layer: settles in 1-2 minutesprocess Allow suspended soil to settle for about aminute. Mark the side of the jar at the top ofthe layer that has settled out. Silt Layer: settles in 1 hour Set jar aside, being careful not to mixthe sand layer; wait ~ an hour. Mark the top of the Silt Layer on theside of the jar. Clay layer: settles in ~24 hours Set jar aside, being careful not to shakeor mix the layers that have settled out. After 24 hours, or when the water isclear (more or less), mark the jar at the The percentage oftop of the clay layer. each layer tells you what kind of soil you Most of the organic matter will be have. floating on the top of the water Project SOUND 7. Sandy Soils Sandy soils are found throughoutSouthern California, but are verycommon near the mountainfoothills, along rivers andstreams, in desert areas andcertain coastal areas. Sandy soils are typicallycomprised of approximately 80 -100% sand, 0 - 10% silt and 0 -10% clay by volume. Sandy soils are light and typicallyvery free draining, usuallyholding water very poorly due tovery low organic content. You may want to concentrate onplants that thrive in sandy soils Project SOUND 8. Are also common in SouthernLoam SoilsCalifornia, particularly in thevalleys and flat areas (floodplains) surrounding rivers andstreams. Loam soils are typicallycomprised of approximately 25- 50% sand, 30 - 50% silt and10 - 30% clay by volume. Loam soils are somewhatheavier than sandy soils Tend to be fairly free draining,again, due to typically loworganic content. A wide range of plants growwell in loamy soils1:1:1 soils Project SOUND 9. Challenges of local sandy soils Poor moisture retention: Because it retainsmoisture poorly, plants in sandy soil suffer fromdrying out quickly Heat stress: Sandy soil does not moderate heatas well as other soils. It heats up quickly duringthe day and cools rapidly at night, stressingplants and making it difficult for tender seedlingsto thrive. Infertility: Sandy soil usually does not containmuch organic matter, and what is there breaksdown more quickly than it does in other types of sandy-garden-soil.html soil, especially in warm climates. Soluble nutrientsquickly leach out with rain and irrigation.Fortunately, native plants pH: coastal and desert sands may be alkalifrom sandy soil regions (pH > 8.0)are well adapted to all ofthese conditions Rooting: Takes a while for roots to gain enoughpurchase to support larger plants Project SOUND 10. Benefits of sandy soils Easier to plant in Harder to overwater; lesssusceptible to El Ninodisasters Roots grow easily in loosesoils Some native plants arespecifically adapted tosandy or rocky soils thesewill thrive in your sandy soil! Project SOUND 11. Keys to succeeding with sandy soils1. Plant with the rains2. Use the Water Zone system to group plants3. Choose appropriate plants4. Start out with small plants5. Mulch with appropriate mulch6. Water correctly; monitor7. If fertilizing, low dose & more often Project SOUND 12. 1. Plant with the rains in sandy soils Why plant with the rains? Saves water soils are naturally moist during the critical first few months Vulnerable plants get the best water possible Vulnerable plants are not exposed to temperature extremes Soils are well-saturated promotes deep/wide root growth Coincides with native plants normal growth cycle; plants are primed to grow at this time Project SOUND 13. 2. Group your plants according to Water Zones Project SOUND 14. Gardens in Mediterranean climates(including S. CA) have three Water Zones Zone 1 no supplemental water; soils aredry in summer/fall. May or may not beplanted. Zone 2 occasional summer water; soil isallowed to dry out between waterings Zone 3 regular water; soil is usually moistto soggy, even in summer. Project SOUND 15. The secret of a water-wise garden is to prioritize waterneeds and group plants with similar requirementsRegular waterPretty drydrought-tolerantplantsWater-wise ; occasional summer water Project SOUND 16. Your Water Zone plan directs many other decisions in your garden plan Choice of plants Soil amending (if any) Use/type of mulch Frequency of watering Type of irrigation system Project SOUND 17. This yard has some natural Water ZonesZone 3 regularlywatered Project SOUND 18. Amending sandy soils: yes or no? The best way to amend is withcomposted organic material Good/necessary choice for: Vegetable gardens Non-native plants Problems (for native plants) May change soil pH Increases nutrient levels may be too high for many natives Not needed many natives are fine with most local sandy soils Project SOUND 19. Selective amendment for special areas Raised beds for vegetable gardens Planters & pots Selective amendment of Zone 3 beds Project SOUND 20. 3. Choose plants that thrive in sandy soils Project SOUND 21. Areas with plants adapted to sandy soils Local areas: Coastal strand/sandybluffs Coastal Prairie/shrubland Southern coast (San Diego Co.) & Baja Northern coast Particularly good forgroundcover plants Plants will need a littleextra water S. CA deserts Project SOUND 22. Beach Bluffs Restoration Project Project SOUND 23. Strand/Bluff plants: Zone 1 with some dry-season fog; many are OK with Zones 1 to 2 in sandy soils Dune Buckwheat Deervetch CA poppy as well as some low-lying plants found mostly quite near the shore: Red Sand Verbena Silver Beach Burr Pacific Cinquefoil others listed for seaside conditions Project SOUND 24. Coastal Marsh plants are Zone 2 to 3 plants unique to our low-lying coastal area Many unique plants that can tolerate sandy soils, salt spray &saltwater, flooding Characteristics: short, spreading; mostly herbaceous perennials;can be used alone or as mixed groundcovers Project SOUND 25. Contouring for water management andconservation Small elevation changes (1-3ft.) in a landscape can workwonders: Provide a greater range of Water Zones: high areas will be drier low areas wetter Allow local native plants to be grown in clay soils provide better drainage Allow good use of seasonal rainfall channel rainwater into depressions (water gardens) or swales Project SOUND 26. This yard has some natural Zone 3 areasCould capture more water from the roofZone 3 regularlywatered Project SOUND 27. Salty Susan/ Fleshy Jaumea Jaumea carnosa Project SOUND 28. Salty Susan/ Marsh Jaumea Jaumea carnosa Coastal region from British Columbia to N. Baja Always found in marshy or moist places: Margins of coastal saltmarshes and tidal flatswhere there is protectionfrom wave action Coastal strand Bases of sea cliffs Named after Jean Henri Jaume Saint-Hilaire (1772-,1464,1465 1845), a French botanist & artist who was interested in practical uses of native plants Project SOUND 29. Salty Susan is one of several local native coastal groundcovers Size: low generally < 1 ft tall spreading to 3-5+ ft wide Growth form: Low, herbaceous perennial groundcover Foliage: Fleshy, succulent gray-green or blue-green color Leaves narrow somewhat like some iceplants Roots: Gerald and Buff Corsi California Academy of Sciences Spreads via rhizomes Project SOUND 30. The flowers are a surprise! Blooms: spring/summer; usually May-Sept in W. L.A. County Flowers: Typical for Sunflower family many flowers in heads Both ray & disk flowers arebright yellow Plants are dioecious separate male & female plants Great nectar & pollen source attracts many insects Seeds: Small Sunflower-like onfemale plants Eaten by birds Project SOUND 31. Salty Susan grows on Soils: Texture: sandy to claymarsh edges pH: any local including alkali (pH > 8.0) Fine with salty soils, seaside conditions; roots exclude salt Light: full sun Water: Winter: needs goo winter water takes some flooding Summer: likes a moist soil best Water Zones 2 to 3 Would be fine with sprinkler overflow, or water from a neighbors yard Fertilizer: none needed; likes 2008 R.C. Brodypoor soils, but light fertilizerwont kill it Project SOUND 32. Salty Susan is a true native groundcover A replacement for Ice Plant onsandy soils, banks In naturally wet areas of thegarden Low spots that get very moist http://www.l