Fall is such an important time in the garden. As we get a reprieve from summer conditions, our plants do, too. Active upper growth slows, and the moderate conditions foster root development for strong specimens heading into winter.

The season is optimal for planting, dividing, and transplanting many of our favorite selections because it fosters healthy root growth. Ahead of the dormant season, plants direct energy to root development rather than producing new leaves and stems.

Fall brings temperature and moisture fluctuations as the seasons transition, including dry spells or periods of cool, damp conditions. To keep our garden looking fresh in autumn and to support healthy plants for winter survivability, regular moisture continues to be essential for trees, shrubs, perennials, and annuals. They continue to absorb water and nutrients ahead of frozen soils (in cold climates).

As temperatures drop, the moisture insulates the roots in frosty conditions and makes for turgid, water-filled roots and stems that stand up to cold weather. Here’s how you can adjust your fall garden watering schedule to account for these conditions.

Fall Garden Watering

It’s vital to adjust your watering in fall.

As we adjust our fall garden watering schedules, it helps first to look at the best ways to water in the fall. The cooling season brings a more relaxed protocol, less intense than those peak summer days spent keeping up with evaporation. But it’s not a time to forget to irrigate. Providing ample moisture through the changing weather is vital to fostering robust root systems and overall health. 

In addition to supporting root development, moisture supports microbes at the soil level that do the important work of decomposing organic material and making nutrients available to plants. Early fall dry spells and drying winds can inhibit microbial activity when there’s less soil moisture available.

Since autumn is the time to foster root growth, how and when we water is important for the best use by the plant. Aim to water at the base to deliver moisture directly to the roots. When hand watering, aim your hose or watering can around the trunk or crown. Soaker hoses are good options for concentrated delivery at low volumes, reducing runoff and maximizing absorption.

The early season marks a great time to do soil testing. Understanding your soil type helps manage irrigation based on drainage and retention. A soil test also indicates available nutrients and any amendments that may be helpful to boost growth. Autumn is ideal for amending soil to improve structure, boost microorganisms, balance pH, and add nutrition. It lets the amendments seep in before spring’s planting and growing season.

Adjusting to Seasonal Conditions

Cool temperatures mean less water loss from evaporation.

When watering the fall garden, it helps to flow with seasonal weather instead of having a set schedule. Rainfall, temperature fluctuations, and windy days help determine moisture needs this time of year. Scale irrigation to what’s occurring in your local microclimate.

Start by reducing irrigation run times from their summer schedule to factor in seasonal variations. Cooling temperatures mean less water loss from evaporation. Fall often brings soaking rains that are enough to support established specimens without supplemental irrigation. 

While we don’t want to forget to water this season, we also want to avoid overwatering. Waterlogged situations create stress, promote fungal diseases, and damage roots. Drought conditions, on the other hand, increase susceptibility to plant problems and pests like spider mites.

Check Soil Moisture

Check the soil moisture before you water.

Soil moisture and plant appearance are the best gauges that it’s time to water. Flagging leaves and stems and crumbly soil are clear signs. Sometimes digging a bit deeper helps us avoid overwatering. 

Check the soil moisture with a simple touch test. Poke beneath the surface to feel for moisture. If the soil is dry about two to three inches deep, it’s time for fall garden watering. Many species rely on about one inch of water per week for healthy growth. In hot, dry spells, they may need more, and less on cooler, shorter days as soils hold moisture longer.

When to Water

Water in the morning rather than the middle of the day.

In the fall, a good rule of thumb is to water early in the day ahead of lowering evening temperatures and potential frost. In warm conditions, watering early helps with water retention and absorption before evaporation as the day warms.

Watering in the morning gives leaves and stems time to dry in the day’s sun and breeze. It prevents damp conditions that promote fungal diseases. But, if a plant shows signs of drought stress late in the day, give it water to keep it strong and nourished against cooling conditions.

Water deeply at each session. Roots with regular, deep sessions fare better than with frequent shallow water. Water deeply and then hold off for a few days to encourage roots to dig deep into the soil. Deep roots tap into moisture reserves, hold water longer, and boost drought resistance. They also help plants withstand cold and hot temperature extremes and provide physical stability.

Watering Through Frost

Don’t ignore watering during frosts.

Plan to continue fall garden watering until heavy freezes and frozen soils. Even though active growth slows, plants continue to absorb water as they continue to grow in moderate conditions until the ground freezes.

Once the soil freezes, roots are unable to uptake water, and dormancy ensues. In winter, they rely on insulating snowpack and freeze-and-thaw cycles for moisture in cold climates. In warmer climates, seasonal rains are usually sufficient to keep the soil from drying out completely.

Both evergreens and specimens that enter winter dormancy (deciduous shrubs and herbaceous perennials) need moisture heading into winter. Evergreens like boxwoods, hollies, and conifers need it to support foliage and roots and prevent winter browning. Regular moisture sets hearty roots and a stress-free start to surviving winter.

Pay Special Attention to New Plantings

Newly planted species need more frequent watering.

With the season’s mild conditions comes the perfect time to add trees and shrubs as well as perennials and cool-season annuals. While mature plants are accustomed to seasonal transitions and cooling days and nights, new transplants lack the settled root system.

New transplants, young plants, and fall divisions need special attention to regular moisture (according to their optimal conditions) to establish before winter. They require more frequent fall garden watering than mature specimens to support their less extensive roots. Keep a check on soil moisture to meet the growing requirements for the new plantings.

The season lends itself to frost-hardy vegetables, so plan to allow about an inch of water per week for the edible landscape. Now is the best time to plant spring-flowering bulbs, which don’t require supplemental water until spring, if at all. They’ll rest in dormancy on stored reserves until warming conditions trigger growth and flowering. Direct sow seeds now to overwinter for spring germination. These, too, don’t need any attention or watering this time of year after sowing.

Turf Watering in Fall Gardens

Reduce the frequency of irrigation once temperatures begin to cool.

Grass continues to grow in the mild temperatures of early fall, and early-season lawns are susceptible to diseases when dry, warm weather takes hold. Continue to irrigate through the season until the turf enters dormancy. Grass stops growing when temperatures drop and the ground freezes, usually in late fall or early winter, depending on the climate.

Reduce the frequency of irrigation once temperatures begin to cool. With less evaporation and less active growth, the blades won’t require the same amount of moisture. During rainy spells, hold off on watering and turn off automated systems. Waterlogged situations present fungal issues in cool, damp conditions. When frost sets in, stop watering for the fall and winter, as roots won’t absorb the moisture in frozen soils.

Early fall is optimal for planting grass seed and infilling patchy areas. If you’ve just seeded, the seedlings will need daily water to thrive (or two or three times a day in early season heat). Water lightly to moisten the soil surface, avoiding excess runoff and pooling. Seedlings usually germinate in two to four weeks.

Continue daily watering until they’re two inches tall, and then reduce water frequency. Water less often, but increase the duration of run time. Watering longer, less frequently, allows for consistent deep watering to promote extensive roots.

Fall Garden Watering for Pots and Containers

Plants in containers need water more often than plants in the ground.

Whether extending the summer display or refreshing containers with fall-flowering selections, continue to provide regular water. Pots dry out more quickly than in-ground plantings, and long-season plantings may be large and thirsty, even in fall. Young plantings will have tender roots as they establish. Do the soil touch test, and water when dry an inch or two below the surface, one or two knuckles deep.

Continue to water potted selections until frost (or until they fade). If planning to overwinter them, move them indoors or to a cool, sheltered space like a garage, shed, or basement. To overwinter, water the containers thoroughly before bringing them to their protected spot. Then, check every few weeks for water needs so the soil (and roots) don’t dry out completely. When temperatures warm in the spring, bring the pots back outside and give them a thorough soaking.

Mulch

Don’t forget to mulch to retain moisture in the soil.

Mulching is a fall garden task that offers moisture retention and regulates soil temperatures. It insulates against fluctuating moisture and icy situations, helping protect roots during freeze/thaw cycles and from potential frost heaving.

A two-to three-inch layer works well heading into cold weather. Tender and borderline selections may benefit from extra protection with more mulch around their crowns. Wait until after frost to add extra crown protection. Leaf mulch, straw, compost, bark nuggets, and aged wood chips are good mulch materials.