Why are petunias becoming leggy and growing less lush foliage?

Q: Do you know why some of my petunias look very scraggly without much foliage compared to others that have beautiful large green leaves? — Nicole W.

A: Petunias might not be as full and large-leaved later in the season for several reasons, often becoming leggy and sparse.

By late summer, unless spent, withered flowers are removed and seed pods often form, which can depress leafy growth, as more energy is going into seed production. Several green seed pods are visible in the photo, and annual flowers, including petunias, can slow down as seed pods form.

Differences in nutrition, or the ability to absorb nutrition, can make plants variable. By the end of the growing season, plants can start to run out of fertilizer. Fertilizing annual flowers weekly can help promote continued strong growth.

Cutting back petunias that seem to be slowing down in mid-summer can help stimulate fresh, larger, vigorous growth capable of increased bloom.

Petunia growth also varies greatly with cultivars, with some types having a greater ability to bloom beautifully throughout the growing season, with few, if any, energy-draining seed pods formed.

Q: We’ve been dealing with lawn rust for about three weeks. My kids go out in the backyard and their shoes are covered in orange dust. Any recommendations would be appreciated. — Jonah J.

A: I can relate, as my shoes and lawnmower are covered with rust-colored dust from my recent mowing. We’re not alone; many homeowners have reported rusty lawns this summer.

The orange powder is the spores of lawn rust fungus. The good news is that the rust "disease" doesn't seem to harm the lawn long-term, although it’s not a preferred situation.

Turf researchers indicate that the rust fungus most typically starts in lawns that are running out of nitrogen nutrition. This can result from less-than-optimum fertilizer application, but it’s also common after periods of high rain, such as we had earlier in the season, which leaches nitrogen out of the lawn's root system.

If you haven't already done so, apply a lawn-type fertilizer, and if rainfall isn’t imminent, apply at least a half-inch of water to dissolve the fertilizer granules, making it available to the root system.

As the grass grows, with its increase nitrogen content, the rust should eventually disappear. A good soaking rain would also wash off the grass, making the orange dust less of a nuisance.

Turf researchers generally don’t recommend lawn fungicides once the rust has already become established because fungicides’ mode of action is mainly preventative.

National brands of turf products do market lawn disease fungicides, which can be tried to prevent further spread of the rust disease. Always follow label instructions when using such products.

Q: When reading the internet, everybody says when watering don’t get leaves wet as it can cause mildew or mold, but if that's the case what about when it rains? We water our plants in early morning around 6 or 7 a.m. — Rich H.

A: At first glance, it might seem like getting leaves wet is a part of Mother Nature’s plan, as rainfall naturally soaks leaves. If it’s natural, it shouldn’t cause harm, right? Why then, are we instructed by reliable plant researchers to avoid getting the foliage wet when watering?

Although leaves getting wet from rainfall is part of nature, it doesn’t mean it’s problem-free. This is especially evident this year, with prolonged weeks of rainy, wet weather this spring that kept foliage soaked.

What resulted was an epidemic of foliage disease on ornamental crabs, lilacs, willows, poplars, and many perennial flowers. The area became a Petri dish of fungal disease, as wet foliage created the ideal breeding ground for fungi. Rainfall, although it’s natural, can still cause problems.

That’s why we avoid getting leaves wet when we water. If Mother Nature would use soaker hoses, we’d have fewer foliage diseases.

Although we don’t have control over rainfall wetting leaves and spreading disease, we can at least not compound potential problems if we focus our own efforts on watering the soil, while attempting to keep leaves dry.

If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at [email protected] . Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.