Lobelia , mark by vivid colour and masses of little , cannular bloom , provide pastime to the garden all summertime . Annual lobelia ( Lobelia erinus ) , grown as a perennial in the fond mood of U.S. Department of Agriculture plant hardiness zone 9 through 10 , is a bushy , modest - growing plant life often used in flower seam and hanging basket . Perennial change , which let in cardinal flower ( Lobelia cardinalis ) and lobelia speciosa ( Lobelia x speciosa ) , are tall , upright flora that attain heights of up to 4 feet . They are stout perennial that get in USDA zones 3 through 9 .
Watering Lobelia
Annual lobelia requires frequent lachrymation during the growing time of year because the short roots remain near the open . Water slowly , using a garden hose or dripping arrangement , to impregnate the grease to a deepness of 6 to 8 inch . permit the top 1 to 2 inch of soil to dry before water again , as badly drained , soggy soil may create root rot or other fungal disease . Perennial varieties benefit from veritable watering the first year . Thereafter , the works are drought - tolerant , and water is necessary only during menstruum of hot , dry weather .
Fertilize to Promote Healthy Blooms
one-year and repeated lobelia varieties profit from program program of a dry , 5 - 10 - 10 or 5 - 10 - 5 fertiliser at planting clock time . toil the plant food into the ground at a rate of about 5 pound per 100 straightforward pes of planting infinite . Repeat every leap for recurrent variety . Although a annual feeding is sufficient for perennials , annual lobelia requires frequent alimentation to hold energy for flower throughout the season . utilize a melted fertiliser with a ratio such as 12 - 4 - 8 , conflate at a pace of 1 teaspoon per Imperial gallon of water every two to three weeks . Always apply fertilizer to damp soil to prevent damage to the plant ; then water thoroughly to distribute the plant food evenly around the ascendant .
Maintaining Healthy Plants
lift back the tips of young annual and perennial lobelia plants by 1/2 to 1 column inch to make full , shaggy plants . Thereafter , shear one-year lobelia by about half its height if it becomes shopworn and leggy in midsummer . To prevent spreading of disease organism , disinfect shears and other cutting tool by pass over the blade with rubbing alcoholic beverage before and after each role . you may also sanitise the blades with a mix of 1 part bleach and 9 part water . Deadhead perennial varieties to keep the plants looking their best and promote growth of flower throughout the growing time of year . To deadhead , twinge off wilted blooms along with the stem down to the next branch or leaf . Perennial and annual miscellanea benefit from 2 to 3 inches of mulch to keep the solution cool and moist during the growing season . Keep a layer of mulch around perennial change to protect the roots during the winter . Divide repeated lobelia every two to three year to keep the plant from becoming crowded .
Special Considerations
Lobelia is a plague - resistant industrial plant ; however , perennial varieties may be discommode by slugs and snails . If the plague is easy , pluck the pests off by hand and strike down them in a pail of soapy water . Otherwise , use slug sweetener at a rate of 1 teaspoon per square yard of planting area . Keep the container tightly closed in , and put in it in a locked place where it is unprocurable to children and pets . works lobelia with tending because some variety , include Lobelia cardinalis , are poisonous if eaten in large quantities .
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