Q: What is the best time of day to water my lawn?

A: Recent studies at CSU demonstrate that the best time to irrigate your lawn is between 10 p.m. and 6 a.m. Research shows that extending the length of time the turf is wet correlates with the formation of disease organisms. Watering between 10 p.m. and 6 a.m. overlaps with the natural dew period, and helps dilute the turf’s naturally exuded fluids, restricting the growth of fungal pathogens.

From a practical point of view, this time of day is usually cooler and less windy, so evaporation losses are reduced. In many areas, water pressure is also highest during these hours, helping produce more consistent application. If it is not possible to water during these hours, diseases can be avoided by watering between 9 a.m. and 4 p.m., but evaporation due to sun and wind will be higher, requiring more water to achieve the same level of effective irrigation. Plus, some cities may have ordinances preventing watering during the day.

Early to late evening is the worst time to irrigate. Not only is the grass leaf wetness period extended, encouraging disease germination and infection, but also the cooling effect increases natural secretions that create more nutrients for fungal growth.

Q: Should I prune my roses to keep them blooming?

A: Heavy rose pruning to remove dead canes and promote overall new growth should have been done in early spring. However, during the flowering period through the month of August, you can encourage more blossoms by removing spent flowers. Stems should be cut just above a five-leaflet leaf. Beginning in September, be careful to cut spent flowers just below the bloom. Otherwise, you may stimulate new growth that can be injured by frost.

Q: How can I produce healthy tomatoes and prevent disease problems?

A: Although many tomato problems are caused by nutrient deficiencies, fungi and insects, good cultural practices can help reduce or eliminate many of the common problems we face in growing healthy tomatoes. Some helpful tactics are:

• Add organic material, such as compost, to improve soil condition
• Rotate crops, planting tomatoes in the same space only once every three to four years
• Select disease-resistant varieties (e.g., VFN)
• Water deeply when the top two inches of soil is dry, but don’t drown the plants
• Use mulch to help reduce fluctuations in moisture levels
• Keep your beds free of plant debris and ensure maximum air circulation around plants.
• Monitor for insects and other pests

Gardening and Insect Fact Sheets are available on-line by clicking HERE.

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This page updated:  June 14, 2007