Lawn & Garden

Monthly Gardening Tips for September

Alicia Lamborn, Horticulture Agent

Lawns:

• You can take a break from watering your lawn this month, but don’t give up on mowing. 

• Allowing the grass to get overgrown and then cutting it back severely is very stressful on your lawn. 

• You should never remove more than one third of the leaf blade at any one time.  For example, if you maintain your lawn at 3 inches, you would need to mow once the grass grows to 4 inches tall.

• Try to mow at the highest recommended mowing height for your grass species.  St. Augustinegrass should be mowed at 3.5 to 4 inches; Bahiagrass at 3 to 4 inches, Bermudagrass and Centipedegrass at 1 to 2 inches.  Mowing at the highest recommended height will leave more leaf surface area for photosynthesis and train roots to grow deeper, resulting in a stronger, healthier, more stress tolerant lawn.

• Grass clippings act as a natural fertilizer when left on the ground, returning nutrients that can be used by the turf for new growth.  If piles of grass form on the ground (caused by infrequent mowing) then raking and removing the grass is acceptable to reduce thatch and disease problems.

• Lawn clippings that are blown onto hard surfaces (streets, driveways, etc.) should be swept or blown back onto the lawn.  If you allow them to remain on those hard surfaces, the clippings will eventually get washed into the road, down the street and into a storm drain, ditch or retention pond.  The nutrients held up in those clippings will quickly be released as the clippings decompose and contribute to nutrient pollution in our waterways.

• Most lawns can be fertilized this month using a complete fertilizer (containing nitrogen, phosphorus, and potassium) such as 16-4-8, 13-3-13, or similar product.  However, in many areas phosphorus is not be needed (a soil test through the extension office will help determine this) and a 15-0-15, or similar fertilizer can be used.

• If you decide to fertilize your lawn this month, be sure to check out the new fact sheet on Fertilizer Rates for Lawns and Landscapes, which has charts that make figuring out fertilizer applications easy.  Also consider using a controlled or slow-release product for longer lasting results without the sudden surge of growth that is so attracting to insects.

Annuals & Perennials:

• Much of September gardening involves keeping the existing plants looking nice until new beds can be planted.

• Sometimes a little trimming is all that is needed to revive your plants, while others may require staking.  Cut out dead or declining portions of plants and remove seed pods which can be saved for future sowing or shared with friends.  Removing old and fading flowers may also encourage new blooms on some plants. 

• Planting annuals and fall-blooming perennials will add some color to the landscape until its cool enough for winter annuals.  Firespike is an attractive fall-bloomer with red flower spikes that provides added interest.  It’s also nematode resistant which makes it a great choice for landscapes with nematode problems.

Shrubs & Trees:

• It is not necessary to fertilize large, established trees and shrubs in the landscape or young trees that are surrounded by fertilized lawn.  Plant roots extend far beyond the edge of the canopy and therefore will receive some of the nutrients applied to the grass.

• If you aren’t planning to fertilize the lawn this fall, you may consider giving your young trees and shrubs a light application of fertilizer, especially if you see nutrient deficiencies.  Summer rains can sometimes deplete the soil of nitrogen which is important for healthy growth.

• If you need to fertilize your young citrus trees, do so this month.  Young citrus need frequent, light applications of fertilizer to stimulate vigorous growth of branches that become the framework of the mature tree, but should not be fertilized between October 1 and February 1 for the first year or two after planting.