Grass grows in three broad stages: a leafy stage, a stage where stems shoot up, and a stage where it flowers and sets seed. In each one the plant puts its energy somewhere different, first into leaves, then into stems, then into seed. The stage that gives the most bulk also gives the poorest feed, so deciding when to cut or graze is always a trade-off between quantity and quality.
Stage One The Leafy Vegetative Stage
Each grass shoot grows from a growing point, the tip of tissue that makes new leaves. In this first stage it sits at or near the soil surface. That is why turfgrasses and young pasture can be cut over and over: a mower or a grazing animal takes leaf tissue but misses the growing point.1EcoClipper. Turfgrass management: mowing height and root development The plant even makes up for the lost leaf by packing more shoots in below the cut height.2EcoClipper. Turfgrass management: mowing height and root development
In the field, this stage looks like clumps of leaves with no visible stem or seed head. Most lawns spend the whole season in this stage because regular mowing keeps them there.
New side shoots (called tillers) form at the base of the plant, and some grasses also spread by underground stems called rhizomes. Kentucky bluegrass spreads by rhizomes, which makes it a dense lawn grass that crowds out weeds.3University of Idaho Extension. Kentucky Bluegrass Growth, Development, and Seed Production In fields grown for seed, though, too much of this spreading makes the stand sod bound, and seed yields drop.4University of Idaho Extension. Kentucky Bluegrass Growth, Development, and Seed Production
For a thin pasture or patchy lawn, tillers are the free fix. More tillers per plant fill gaps without reseeding, and regular cutting that isn’t too low encourages them.
The plant still needs some leaf to catch sunlight. Grazing or mowing everything to the soil slows regrowth. In pasture, move animals off while a good amount of green leaf remains instead of waiting for the paddock to look bare. On a lawn, take off only a portion of the blade at each mowing.
Stage Two Stem Elongation or Jointing
Grass needs signals to switch from making leaves toward flowering: a cold spell and the right day length.5Forage Information System. Transition Many cool-season grasses must get the cold period first before they can flower.6Forage Information System. Transition Kentucky bluegrass needs a long, unbroken spell of cold with short days.7Crop Science. Environmental Control of Floral Induction and Development in Kentucky Bluegrass Day length is sensed in the leaves, which send a flowering signal up to the growing point.8Forage Information System. Transition
Then the stem stretches. The sections between joints lengthen as cells divide and then stretch.9PubMed Central. Gibberellin-mediated internode elongation in grasses with a focus on bamboo: molecular pathways and regulatory networks The growing point rides up inside the stem, well above where it sat in stage one. Once it is that high, a close graze or cut can remove it, and the plant has to replace that shoot with a new tiller.
To check for jointing, split a stem lengthwise and look for the growing point lifted above the soil. Run your fingers along the stem for small swollen joints, called nodes. The stems feel firm and hollow rather than like soft rolls of leaf. Once you can see nodes, seed heads are on the way within weeks.
A lawn can skip all this. Grasses that need cold may stay leafy after a mild winter, and lawns mowed weekly rarely show stems because the growing points get clipped. Seed heads in spring usually follow a normal cold winter and are not a sign of disease.
For grazing, hitting tall stems hard during jointing slows regrowth, since new tillers must start over. Lighter, earlier grazing keeps more plants leafy, and leaving more height protects growing points.
Stage Three Boot Heading and Seed
- Boot stage: the seed head sits wrapped inside the sheath of the top leaf, called the flag leaf.10SDSU Extension. Forage Plant Growth and Development
- Heading: the seed head begins to poke out and spread open.11SDSU Extension. Forage Plant Growth and Development
- Flowering and seed fill: these follow as the head matures.
You can spot boot by hand. Squeeze the top of the stem and feel for a firm bulge inside the leaf. The flag leaf is the last leaf on the stem and is often shorter than the others. Boot is a short window, often a week or so before heads show, and recognizing it lets you plan a hay cut before quality drops.
After heading, the head spreads open and tiny flowers open on it over several days. Pollinated flowers form seeds, which fill with starch and other reserves as the head matures. Over this seed-fill period the head turns from green toward straw or tan as the seed ripens. All of this pulls the plant’s energy into seed, so leaf growth largely stops.
Then the seeds loosen. A weak zone forms where each seed attaches, already present when the head emerges.12PubMed Central. Histological Characteristics, Cell Wall Hydrolytic Enzymes Activity and Candidate Genes Expression Associated with Seed Shattering of Elymus sibiricus Accessions In some grasses it starts breaking down about two weeks after heading.13PubMed Central. Histological Characteristics, Cell Wall Hydrolytic Enzymes Activity and Candidate Genes Expression Associated with Seed Shattering of Elymus sibiricus Accessions Enzymes digest the cell walls in that zone, while grasses with more woody tissue there hold their seed longer.14PubMed Central. Exploring the mechanism of seed shattering in Psathyrostachys juncea through histological analysis and comparative transcriptomics
If you are harvesting seed, you have to do it before the heads shatter. Shattered seed can thicken a pasture naturally. Letting a lawn go to seed adds little density compared with what tillering does.
How Feed Quality Changes Through the Stages
Quality starts to slip as soon as regrowth begins, because stems build up and hard-to-digest lignin is laid down in leaves and stems.15EDIS. Factors Affecting Forage Quality The longer you wait between cuts, or the longer the rest between grazings, the lower the quality generally gets.16EDIS. Factors Affecting Forage Quality At seed set, yield is the highest it will get, but quality is low, with more fiber, less protein, and more stem than leaf.17Livestock. Importance of Forage Growth Stages When Grazing Cattle Cool-season grass also becomes less tasty to animals as it turns stemmy at heading.18Farm and Dairy. Understanding the physiology of pasture grasses
Animals can’t break lignin down, and it locks up the fiber around it. Stems carry more lignin than leaves, so as the stem share grows, the feed gets less digestible.
Match the stage to the animals. Milking cows and young stock have high needs and do best on leafy grass. Dry or maintenance animals can use more mature, bulkier forage. For hay, cutting around boot balances bulk and quality, while cutting at full seed gives lots of bales that feed poorly.
A common mistake is waiting for more growth. The extra bulk is mostly stem, which animals eat less of, so rotating sooner often gives more usable feed overall.
How Stored Energy Brings Grass Back
Grass stores carbohydrates mostly after leaf growth is done, when leaves still make plenty of sugar but new growth needs little.19Colorado State University Extension. Grass Growth and Response to Grazing The surplus builds up in the roots and the crown, the base where shoots meet roots.20Colorado State University Extension. Grass Growth and Response to Grazing It can also sit in buds and the bases of shoots.21Rangelands Gateway. The 3 Stages of Grass Growth Explained This store keeps the plant alive while dormant and powers the first few leaves next spring.22Rangelands Gateway. The 3 Stages of Grass Growth Explained
The crown is a compact base that sits at or just below the soil surface. Because it is low, it is protected from grazing, mowing, and winter cold better than the leaves are. It holds buds that can produce new shoots, so a plant with a healthy crown can come back after damage.
Late-season grazing cuts into the time plants have to store energy. Plants that go into winter with low stores green up slower in spring.
Regrowth after a cut starts slowly because the first new leaves draw on stored energy. Cutting again too soon drains the store further.
What Low Cutting Does to Roots
Grass roots grow in a yearly cycle: many new roots in late winter and spring, few in summer, with roots formed in autumn and winter living longest.23Grass and Forage Science. SEASONAL VARIATION IN APPEARANCE AND GROWTH OF GRASS ROOTS On golf-green bentgrass, mowing slightly lower meant less new root, shallower roots, and more dead root.24Crop Science. Mowing Effects on Root Production, Growth, and Mortality of Creeping Bentgrass Lowering the cut in summer hurt roots more than keeping it higher, and it can lead to thinner turf.25Crop Science. Mowing Effects on Root Production, Growth, and Mortality of Creeping Bentgrass The turf mowed lowest also recovered root mass more slowly in early autumn.26Crop Science. Plant Growth Regulator and Mowing Height Effects on Seasonal Root Growth of Penncross Creeping Bentgrass
Summer is the risky time because roots grow little then, so the plant has few new roots to replace any that are lost. Heat already stresses the plant, and a low cut leaves less leaf to supply the roots with sugar.
On a home lawn, raise the mower in summer heat rather than lowering it, and avoid taking off much leaf at one cut. Autumn is a key time for root building, so avoid scalping then. The same idea applies to pasture: leave stubble when grazing.
Cool Season and Warm Season Grass Timing
Cool-season grasses grow most in spring and autumn, and warm-season grasses grow most in summer. In a cool climate, warm-season grasses matched or beat cool-season yields despite growing for a season about 40% shorter.27Agronomy Journal. Comparative Growth Analysis of Cool‐ and Warm‐Season Grasses in a Cool‐Temperate Environment They grew about twice as fast and got more than twice the growth from each unit of nitrogen.28Agronomy Journal. Comparative Growth Analysis of Cool‐ and Warm‐Season Grasses in a Cool‐Temperate Environment They also stay dormant in cool weather, often turning tan after the first hard frost, which concentrates their grazing or mowing window in the warmest months.
Some cool-season grasses go summer dormant in heat and long days, usually after flowering.29PubMed Central. Summer Dormancy in Perennial Temperate Grasses They stop growing, let some leaves die back, and move nutrients into storage.30PubMed Central. Insights into the Drought and Heat Avoidance Mechanism in Summer-Dormant Mediterranean Tall Fescue
So brown cool-season grass in midsummer may be resting, not dead. Watch for green-up when cooler weather and rain return. Mixing in warm-season grass can fill the summer gap. Before you blame disease, know which type of grass you have.
Water and Fertilizer Through the Stages
Germination is generally the stage most sensitive to drought.31PubMed Central. Effect of Water Deficit on Germination, Growth and Biochemical Responses of Four Potentially Invasive Ornamental Grass Species For dryland grasses, whether seeds sprout and emerge decided over 90% of how many plants survived the first season.32Journal of Applied Ecology. Seed and seedling traits affecting critical life stage transitions and recruitment outcomes in dryland grasses On established turf, letting it go until it wilts before watering can cut growth by up to 35%.33Agronomy Journal. Water Consumption and Growth Rate of 11 Turfgrasses as Affected by Mowing Height, Irrigation Frequency, and Soil Moisture
A seed that has begun to sprout has a tiny root and shoot and no reserves to survive drying out. If the soil surface dries even briefly after sprouting begins, the seedling can die before it is established.
For a new seeding, keep the surface moist until seedlings emerge, with light, frequent watering. Shift to deeper, less frequent watering once roots form. Don’t wait for wilting on established turf.
Nitrogen has its own timing. In one seed grass, splitting nitrogen, most in the leafy stage and the rest as heads began forming, gave the most seed.34Crop Science. Nitrogen Management, Nitrogen Use Efficiency, and Seed Yield and Quality of Creeping Signalgrass Timing nitrogen to avoid heavy rain also reduces how much washes away.35Plant and Soil. Strategic timing of nitrogen fertilization to increase root biomass and nitrogen-use efficiency of Lolium perenne L.