By Robert Pavlis, Master Gardener
Grass is found in almost every garden and lawn care is part of a gardener’s job. What should you do, and not do, to your grass in spring? In this post I will look at lawn maintenance for temperate climates that grow cool growing types of grass.
Spring Lawn Care:
The sun is shining, the snow is gone and I want to get outside and do some gardening. It is only April 1 but I know the gardener inside of you is also tugging hard to get going.
Here is a simple rule for caring for your lawn in spring – DO NOTHING!
At this time of year the ground is wet and the soil compacts easily. Stay off the grass so you don’t compact the soil. The best thing you can do for your lawn in zone 5 is to stay off of it until May. In warmer zones you can walk on it a few weeks sooner, and in colder zones stay off even longer.
The first job many people do is rake their lawn to get rid of grass thatch, but that is a bad idea.
Some thatch is good for a lawn. It keeps the roots cool in summer, and helps maintain moisture in the soil. Too much thatch can be a problem since it prevents water and air from getting into the soil.
How much thatch is too much? A thatch layer of less than 1 inch (2 cm) is not a problem and should be left alone. Raking small amounts of thatch with a rake causes several problems. Walking on the grass while you are doing it compacts the soil. Raking damages the grass roots. And removing small amounts of thatch exposes grass roots to more heat in summer.
If you really do have a thatch problem rent a dethatcher to do the job properly, or get a professional to do it for you. It should be done in fall – not spring.
Rakes and dethatching blades for lawnmowers are not very effective.
Rolling The Lawn:
You are probably thinking that the lawn is very irregular and it really needs to be rolled while the ground is still soft. This is a very common myth. Rolling will flatten out the irregularities and make it look better, but it also compacts the soil, making it harder for grass to grow.
An existing lawn should never be rolled.
What do you do about the irregularities? One option is to do nothing. Small irregularities will work themselves out on their own and will less visible once the grass has grown more.
If you want to fix the problem, follow these rules. For spots that are slightly low, add soil on top of the low spots every year. Over time your grass will become flatter.
For high spots and major low spots, it is best to use a flat bladed shovel to dig up a section of grass that is about 1 inch thick. Then either add soil or remove soil. Replace the piece of grass, and keep it well watered until new roots form.
The best way to fight weeds in a lawn, without using herbicides, is to grow thick grass by fertilizing in spring and fall, watering when needed and doing a core aeration at least once a year.
When selecting your fertilizer, make sure the middle number is zero (e.g. 15-0-3) so that you are not adding unnecessary phosphates to the environment. Most soil does not need more phosphorus and many soils do not need more potassium – the third number.
It is common practice to fertilize in early spring, but that’s not the best time. Roots grow best in cool weather, and in early spring you want your grass to grow roots – not leaves. Adding nitrogen to the soil in early spring causes leaf growth instead of root growth.
Don’t fertilize until mid May in zone 5; sooner in warmer areas, and later in colder areas. You can even skip the spring fertilizer and only fertilize in fall. If you do fertilize in spring, don’t add more than 1 lb/1,000sq ft of Nitrogen.
Synthetic or Organic Fertilizer:
Synthetic or organic fertilizer – which is better?
The reality is that plants can’t tell the difference between a nitrate molecule from a synthetic or organic source. As reported in “What is Organic Fertilizer?”, they are exactly the same.
The difference in the two forms of fertilizer is that synthetic fertilizers provide the nutrients quickly, and organic add them slowly over time. Both work on lawns. Organic material will also improve soil structure whereas synthetic fertilizer will not. For most non-lawn gardens organic would be a better choice, but for lawns we do want a quicker feed, especially in the north where summers are short. Synthetic fertilizers are also easier to apply since you can’t add a thick layer of something like compost or manure all at one time. A thick layer will kill the grass.
Plants need lots of air and water in the soil. In fact, great soil will contain 25% air, and 25% water. The problem with lawns is that we walk on them and compact the soil, squeezing out the air and water. As soil compacts, grass roots have a much harder time to grow, which results in thinner grass and more weeds.
The solution is simple – don’t walk on grass. But that is not very practicable for most homeowners, so the next best thing you can do to reduce compaction is to core aerate the lawn at least once a year. Core aeration is done with a small machine that pulls out plugs of grass and soil every few inches, over the whole lawn. These plugs are left on the lawn to disintegrate during the following week. They are unsightly for a few days – but they’re very necessary.
Don’t aerate by poking holes in the grass because that only compacts the soil even more. Some companies sell special rake-like devices with prongs on the end for poking holes – don’t use them.
Lawn service companies usually offer two types of aeration; poking holes and core aeration. I once asked a sales person why they offer the hole poking service – didn’t they know this is not good for lawns? They told me that they know it does not work, but a lot of customers prefer it since it does not leave ugly plugs on the lawn. Dumb!
Myth: wearing golf shoes while mowing the lawn will aerate the soil.
All this does is compact the soil even more – don’t do it.
Overseeding Your Lawn:
The benefits of overseeding your lawn is mostly a myth. If you don’t have significant bare spots, overseeding will do very little to make the grass thicker. Seed needs to come in contact with soil to absorb moisture and grow roots. The problem with most overseeding is that the seed lands on either the crown of the plant, or on the thatch layer. In either case it does not touch the soil to get enough water to germinate properly. Instead of overseeding, focus your efforts on growing your existing grass thicker.
Overseeding a lawn that has good-sized bare spots does work. In this case the seed is added only to the bare spots and then racked into the soil so that it makes good contact with the soil. This is best done in fall.
For more information, including articles on Dethatching Lawn Thatch; Using Lawn Rollers; Fertilizers; and more, visit Robert Pavlis’s website: www.gardenfundamentals.com