by Lisa Johnson, horticulture educator for Dane County UW-Extension
Fall is the most important time to fertilize your lawn. If you only do it once a year, do it now! Research, based on the growth cycle of turfgrass, shows that Labor Day is the best time to fertilize. Memorial Day is the second-best. Fertilizer is most effective when the highest amounts of root and shoot biomass are present to absorb and use it. Nitrogen, phosphorus and potassium are the macronutrients that lawns need most. Test your soil before applying fertilizer blends so you know whether fertilizer is needed and what type to buy.
Apply no more than 1 pound of nitrogen per 1,000 square feet per feeding, and a maximum of 4 pounds per year. Nitrogen is usually the limiting factor in turf growth, because it doesn’t accumulate in soils as phosphorus and potassium do. Lawn maintenance fertilizers with 25 to 50 percent of the nitrogen content in a slow-release, or water-insoluble form are best. They release nitrogen slowly rather than all at once, minimizing nitrogen loss due to leaching. Leaving grass clippings on the lawn and applying 1/4 of compost reduces nitrogen fertilizer needs, too.
There is a statewide ban on phosphorus in turf fertilizers, with an exception for some organic products in some counties of Wisconsin. Phosphorus, which helps build strong roots, may be recommended in soil tests if you are starting a new lawn from seed or maintaining a lawn in low-phosphorus soils. If testing recommends application, bring your soil test results to the store in order to purchase turf fertilizers containing phosphorus. In south-central and southeastern Wisconsin, we often have high to excessive amounts of phosphorus in our soils (especially in urban soils), so more is not recommended. However, this isn’t the case statewide.
Potassium helps turf increase its disease and drought resistance and prepare for winter dormancy. Potassium is present in higher amounts in winterizer turf fertilizers, but this doesn’t mean you can only apply it in fall. In many areas of Wisconsin, we have high potassium levels in soils, so it may not be needed.
Dry fertilizers are easier (and quicker) to apply, especially when large areas are involved, and though they are slower to take effect, they last longer. In most gardens, wet fertilizers are used for foliar feeding, sprayed directly on plant leaves for immediate uptake. They produce rapid results, but their action is short-lived.
Dry fertilizers are usually mixed with soil before planting. Later in the season they are used as side dressing, spread in a narrow band about a foot away from growing plants and then scratched in.
Ideally, dry fertilizers break down slowly, providing a steady stream of nutrients with minimal danger of root burn, weak hypergrowth, and other problems caused by too much, too soon. In practice, however, this doesn’t always work out. Dry chemical formulations are highly soluble, and while they are more durable than liquids, they disperse rapidly in warm, wet weather. They can work well, but it is important to use minimum amounts, mix them well with the soil, and keep them away from plant roots.
Most organic amendments, on the other hand, are minimally processed. They must be broken down by weather and soil microbes before the nutrients they contain are available to plants. While there are exceptions, as a general rule these natural products pose none of the dangers of rapid breakdown, and unlike chemical fertilizers, they offer long-term soil-building benefits. But there’s no denying they’re slow to download; you have to plan well ahead.
by Sharon Morrisey, consumer horticulture agent for Milwaukee County
Research by University of Wisconsin turf specialists suggests new recommendations regarding summer fertility for lawns. An application of lawn fertilizer around the Fourth of July might be warranted.
This recommendation is made for:
Lawns less than 15 years old
Older lawns that have not been regularly fertilized for the last 15 years
Lawns where the clippings are collected, rather than left on the ground
This summer application is in addition to fertilizing around Memorial Day and Labor Day. Each application should provide 3/4-1 pound of actual nitrogen per 1,000 square feet of lawn, but follow the manufacturer’s recommendations on the bag.
Fertilizer applications should be followed by watering or applied just before it rains.
Here’s a question that tends to divide folks right down the middle. When it comes to the wisdom of feeding trees, expert opinion is sharply — in some cases acrimoniously — divided, but the weight of modern practice is increasingly in favor of the dictum that less is more.
A small amount of fertilizer is fine. It will help compensate for the absence of natural fertility that tends to distinguish lawns (where all the leaf litter gets raked up and there is no understory to speak of) from woodlands (where the trees are nourished by lots of decayed plant material).
But before you go out and buy tree food, remember that the small amount needed is likely to be already present as a by-product of fertilizing the lawn. Once you get into adding more than that, it’s likely you will do more harm than good — if you do anything at all. The harm comes because fertilizer pushes the tree into making lots of tender, soft growth. It’s lush, it’s green, it’s very impressive, and it’s also highly vulnerable t insect attacks, climate stress, and the myriad fungus diseases that would be thwarted by tougher tissue.
The doesn’t-do-anything-at-all situation results from putting the food where the tree can’t get at it. Most of a tree’s feeder roots are in the top 10 to 18 inches of soil, and most of them start near the out edge of the canopy (the drip line) and spread outward from there. That means using an injector to put the eats down deep is not going to do much except pollute the groundwater. And spreading the tree’s meal close to its trunk will be just as fruitless.
The bottom line: keep feeding to a minimum unless the tree is in a container where it cannot possibly find nourishment on its own. And if you do use fertilizer on a landscape tree, spread it in a wide band that works out from the drip line.
Everyone wants the perfect sea of smooth green lawn with nary a hint of weed, bare spot, or discolored grass. Alas, easier said than done! However, here are 5 steps that will help create a beautiful and naturally weed-resistant lawn.
Prepare the soil. Though they are seldom thought of that way, expanses of mown grass are actually very intensive gardens. Loose, fertile soil of the right pH is even more important for good lawns than it is for tasty tomatoes or lavishly blooming shrubs.
Invest in the best seed, use enough of it, and plant it at the right time. The first defense against weeks is a turf that is thick enough to prevent them from getting the light they need to sprout and grow. The grass won’t be thick if you’re stingy with either quality of quantity, and it won’t fill in properly unless you give it a proper start.
Think long term. Be sure the seed mixture comprises grasses that will be long lived, such as red fescues and bluegrasses. There should be only a very small amount of rye grass, if there is any at all. Rye grasses grow quickly, helping the lawn to look good fast and preventing the growth of some weeds. But because they are up so quickly, they steal nutrients, water, and light from slower-growing but more durable types. As a result, newly established turf has a lot of rye in it. This is fine for a short while. But even perennial rye dies out within a few years, and when it does it leaves a whole lot of room for weeds to move in. A sprinkling of rye can be used if you are the impatient type. But you’ll have better long-term weed control if you go for the slow stuff and hand-weed for the first year or so while the good grasses are settling in.
Adjust the mower to the season. No matter what height you like your lawn, letting it get a bit shaggy in summer — a good 3 inches tall — will cut down on weeds. The taller gras provides more shade, keeping the grass roots cool and healthy while making it harder for weed seeds to sprout and find the light.
Don’t water if there’s a drought. This may seem counterintuitive, and it isn’t entirely true: if you have an endless supply and can water the lawn thoroughly, by all means go ahead. But if water is limited, you’re much better off letter the lawn go dormant than trying to give it “just enough to stay alive.” Grasses naturally lie low and turn brown during droughts. They aren’t dead — they’re just sleeping. A small amount of water won’t be enough to keep grasses green, but it will keep the lawn green, because the watered weeds will thrive
Organic Weed & Feed
For those of us who become frustrated at the growth of weeds in our lawns when we’re using organic fertilizers, there is one help: corn gluten meal, a by-product of corn milling. It is quite high in nitrogen, which makes it a good fertilizer for grass. And it will prevent weed seeds from growing.
But — there’s always a but — that’s it. Corn gluten kills by drying up the baby sprouts as soon as the seed cracks open. It has no effect on perennial weeds (other than to encourage them) or on annual weeds that are already growing.
Furthermore, it must make good contact with the weed seeds in order to kill them, not a problem on bare soil but a tricky proposition if the grass is reasonably thick. It works best when the soil is warm, by which time many annual weeds have long since been up and about. And it lasts for only about six weeks, so you have to apply it frequently.
All that said, corn gluten is a relatively benign fertilizer, and it can help control annual weeds if you use it faithfully, from spring to fall, for a couple of years. It is nontoxic and, in home-garden quantities, safe for the environment.
Many gardeners are worried that the products being used to keep that beautiful lawn are, in fact, endangering the environment. With that in mind, then, there is a constant desire to use less damaging chemicals but, at the same time, retain a beautiful lawn. One solution may be corn gluten meal, a by-product of corn milling. It is quite high in nitrogen, which makes it a good fertilizer for grass, and it will prevent weed seeds from growing.
Corn gluten meal being applied by a broadcast spreader
Corn gluten kills by drying up the baby sprouts as soon as the seed cracks open. However, it has no effect on perennial weeds or on annual weeds that are already growing. Furthermore, it must make good contact with the weed seeds in order to kill them — not a problem on bare soil but a tricky proposition if the grass is thick. It works best when the soil is warm, by which time many annual weeds have long since been up and about. And it lasts for only about six weeks, so you have to apply it regularly.
Corn gluten is a relatively benign fertilizer, and it can help control annual weeds if you use it faithfully, from spring to fall, for a couple of years. It is nontoxic and, in home-garden quantities, safe for the environment.
One of my favorite hand tools for “popping” those weeds out of the lawn
There is no panacea, however — you cannot go totally organic and control 100% of weeds in your lawn unless you have some handy tools for digging out the weeds. There are a lot of really good hand tools to help you tackle those weeds, though, and maybe a cleaner environment for our kids and grandkids is worth the extra effort.
Such a beautiful time of year with the colorful leaves huddled together in the trees. Unfortunately, they don’t stay on the trees, leaving us with the chore of how to dispose of the leaves. Some people choose to leave them on the ground until spring, which is a wonderful idea for your gardens but can kill the grass on your lawn. Here are some ideas for using the leaves:
When they’re completely dry, rake them into a big pile and have your kids or grandkids run and jump into the pile. Remember how much you enjoyed that when you were a kid?! I grew up in the country and we could also burn leaves; I still miss that smell of burning leaves and branches.
Using your lawn mower, mulch the leaves onto your lawn thereby providing a wonderful source of nutrients as the leaves decompose over the winter and spring. Better than buying expensive fertilizer each year!
Gather and mulch the leaves to use in your compost bin or compost pile. You can use whole leaves, but shredded leaves will break down more quickly to provide that ‘black gold’ compost to use in the spring. Note: continue to add your vegetable scraps and egg shells to your compost heap through the winter. You may not be able to turn the pile as often in the winter, but the nutrients will be there as the snow melts into the pile. Never add meat by-products, fats, animal waste, or leaves or stalks from diseased plants.
Remove the leaves from the lawn and put them around your shrubs and perennials in the garden. They’ll help conserve moisture around the plants, and also stabilize the soil temperature to reduce the fluctuations of freeze and thaw that tear plant roots and heave them from the ground. A 2- or 3-inch mulch of autumn leaves will at least partially decay over the winter, releasing vital nutrients and improving soil structure, but be sure to rake away any leftovers in the very early spring before the perennials and bulbs start peeking up. Large piles of whole leaves will provide great insulation, but they can also turn into soggy mats that smother emerging plants.
Finally, if you must, rake the leaves into the street for the municipal removal teams. Note: the city knows what to do with all of that garden and lawn waste they pick up around the city: they turn it into compost and mulch!