Your Guide to Fall and Winter Lawn Maintenance in San Antonio

This is a key time in lawn care and has been made difficult by the dry, hot weather we have experienced.

Lawn fertilization: When you have been able to water your lawn and it is relatively green, it is time for fall fertilization. Fertilizing with Winterizer products, with a 3-1-2 ratio of nitrogen to phosphorus and potassium, increases the lawn’s ability to tolerate cold weather and contributes to rapid greening in spring.

An example of a fertilizer with a ratio of 3-1-2 is 18-6-12. Eighteen percent is a nitrogen source, six percent is a phosphorus source, and twelve percent is a potassium source.

Winter fertilizers have a fast-releasing nitrogen source so the nitrogen can be quickly absorbed by the plant and organized within the cells to provide the chemistry needed for winter cold tolerance and quick spring greening.

All of this works well when the lawn grass is green and can transpire to draw the nitrogen into the roots and into the plant. When the lawn grass is brown, much less water moves through the plant (transpiration) and the nitrogen is not absorbed. This likely means that the nutrients in the fertilizer are being wasted or otherwise used by the germinating winter weeds.

For the brown lawns this year, fertilizing may not be efficient. Wait until next spring.

Spread wildflower seeds on vacant lots and other open areas. There is no need to prepare the soil, but the seed does need to reach bare soil. Most wildflower seeds need full sun, but Salvia coccinea and blue curls thrive in the shade.

There is still time to lightly prune and fertilize your roses to prepare for fall bloom. Remove dead and crossed stems. Slow release lawn fertilizer works well as a fertilizer.

Thin your iris bed to leave 18 inches between the rhizomes. Iris is not eaten as a deer and is very drought tolerant. Plant new beds in full sun with the tip of the rhizome level with the surface of the soil.

It’s a good time to plant broccoli, cabbage, cauliflower, kale, Brussels sprouts, Swiss chard, and grafts in the garden. Plant carrots, beets, beets, radishes, rutabaga, and lettuce seeds. Lettuce seeds should not be covered with soil.

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Pre-emergence herbicide: Usually September 1st is the recommended time to use a pre-emergence herbicide to prevent weeds like bedstraw, dandelions, thistles, chickweed, henbit, rescue grass, annual bluegrass and beggar lice products like Amaze, Dimension or XL in early October, since not a lot of seeds germinated in dry, hot weather.

If your lawn and vacant lots are brown and sparsely covered with vegetation, it can be assumed that the weeds will fill the available space very quickly once the temperatures cool down and we get some rain. It is not uncommon for the ground to be covered with deep, lush thatch or rescue grass.

Winter mowing the lawn: In my experience, there doesn’t seem to be any real benefit in mowing lower or higher in winter than in summer. The key is to keep mowing, especially if you haven’t applied a herbicide before emergence.

Mowing once a week or even every two weeks does a pretty good job of keeping the weeds under control. Rescue grass, annual bluegrass and horse weed respond particularly well to frequent mowing. Mowing the weeds can turn them into sustainable winter lawns that are attractively green all winter without watering.

New and existing shade tees: Shade trees are an important part of landscape and lawn performance. If you want more shade to reduce air conditioning costs and make it more comfortable to be outside in hot weather, well-placed shade trees are important.

Fall is the best time to plant them. Recommended varieties include live oak, Texas red oak, Mexican white oak, cedar elm, Mexican sycamore maple, chinkapin oak, and bur oak.

On the other hand, mature shade trees reduce the amount of sun that is available for lawn grass to grow in the long term. It’s not uncommon for there to be so much shade that even St. Augustine grass doesn’t work well.

In my opinion, the shade is more valuable than a thick, lush lawn. Additionally, if you have too much shade for lawn grass, there are plenty of shade tolerant ground covers that can replace grass. Liriope, sedge, moon grass, English ivy, Asian jasmine, and dwarf gruellia are good options.

Calvin Finch is a retired horticulturalist from Texas A&M. [email protected]

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