Physiological disorders

How the Problem Manifests

After autumn planting of garlic, during winter thaws or early spring, you may notice that cloves are literally pushed out of the soil, appearing on the surface or protruding significantly above the ground. The roots may be partially exposed, making the plant vulnerable to freezing and drying out.

Why This Happens

The main cause of heaving is freeze-thaw cycles in the soil, which occur during snowless winters or periods of thaw. Moisture in the topsoil freezes and expands, pushing the clove upward. After the soil thaws, it settles, but the clove remains in its new position (Engeland, 1991).

The second factor is insufficient planting depth. If a clove is planted at a depth of less than 5–6 cm, the soil's frost heave forces are sufficient to push it to the surface. Light, sandy, and peaty soils, which freeze and thaw more severely, are particularly prone to heaving.

The third factor is continued growth. Garlic does not enter deep dormancy: during thaws at +5…+10 °C, root growth may resume, further "pushing" the clove upward. Research shows that garlic roots can continue growing even at near-zero temperatures if the soil is not frozen solid (Rabinowitch & Kamenetsky Goldstein, 2020).

How to Prevent It

Planting depth should be at least 5–6 cm from the clove tip to the soil surface (Engeland, 1991). On light soils, planting up to 7–8 cm deep is acceptable.

Mulching is an effective protection method. A mulch layer (straw, dry leaves, mowed grass) 5–10 cm thick acts as a thermostat: it smooths out soil temperature fluctuations, reduces freezing depth, and prevents the formation of an ice crust. Mulch also helps retain snow cover, which acts as natural insulation (Engeland, 1991).

Rolling or firming the soil after planting improves contact between the clove and soil particles, reducing the likelihood of heaving. Lightly firm the soil with your hand or foot, without over-compacting it.

Choosing the right planting time. Garlic should be planted 2–4 weeks before persistent frosts arrive, allowing cloves to root but not begin active growth. This timing varies by region, but the rule of thumb is: after planting, 3–4 weeks should pass before the soil freezes, with average daily temperatures of +5…+10 °C (Engeland, 1991).

What to Do If You Spot It

If heaving has already occurred, cloves can be carefully pushed back into the ground without damaging the roots. In cases of severe heaving, where roots have already dried out, it is advisable to hill the cloves with soil or compost to protect them from further freezing. Plants with severely damaged root systems are best removed—they will not produce a full crop.

How the Problem Manifests

Garlic freezing manifests differently depending on the growth stage. In winter or early spring, you may notice that some plants do not emerge in spring, or emerge weak, with yellowed and deformed leaves. "Bare patches" in the bed—areas where garlic did not sprout at all—are often observed. With severe freezing, cloves become soft, watery, and have an unpleasant odor.

Why This Happens

Garlic is a frost-resistant crop, but its cold hardiness depends on the variety, growth stage, planting depth, and soil condition.

In winter, garlic can freeze for several reasons:

1. Snowless winters with severe frosts. Snow is a natural insulator. Without snow cover, at air temperatures below –20 °C, the soil can freeze to the planting depth (10–15 cm). The temperature in the clove zone can drop to –10…–15 °C, causing cell death (Engeland, 1991).

2. "Wet" freezing. When frost returns after a thaw, water in the clove tissues turns to ice, rupturing cell walls. This is especially dangerous if the garlic has started to grow and then frost hits.

3. Weak, unprepared plants. Garlic planted late, without time to root, or grown on poor soils, loses frost hardiness. Such plants have a poorly developed root system, and the clove does not receive adequate protection from freezing.

4. Late spring frosts. Garlic shoots that emerge early in spring can be damaged by frosts down to –5…–7 °C. Plants that overwintered with insufficient "hardening" are especially vulnerable (Rabinowitch & Kamenetsky Goldstein, 2020). Damaged leaves turn yellow and die, reducing the yield.

How to Prevent It

Variety selection. Spring garlic always freezes in winter—it is planted in spring. For autumn planting, choose winter varieties adapted to the local climate. In regions with severe winters, preference is given to bolting (hardneck) varieties, which are generally hardier than non-bolting (softneck) types (Engeland, 1991; University of Minnesota, 2024). Elephant garlic (Allium ampeloprasum) is less winter-hardy and often freezes in cold regions (Engeland, 1991).

Planting depth and mulching. As with heaving, deep planting (5–6 cm) and mulching protect against freezing. A mulch layer of 10–15 cm provides reliable protection during snowless winters (Engeland, 1991).

Planting time. Plant garlic so that before persistent cold sets in, it has formed a developed root system (at least 20–25 cm long) but has not begun actively growing leaves. The most winter-hardy plants are those that enter winter with 1–2 formed leaves but a powerful root system.

Snow retention. If winters in your region have little snow, consider snow retention measures: installing shields, planting windbreak crops, leaving high stubble in adjacent areas.

Soil improvement. Plants grown on fertile, structured soils with good drainage are more resistant to freezing. Adding organic fertilizers (manure humus, compost) increases winter hardiness (Engeland, 1991).

What to Do If You Spot It

Damaged plants that have not completely died can sometimes be saved: fertilize with a complete mineral fertilizer (NPK) and ensure regular watering. However, the yield from them will likely be lower, and the bulbs smaller. In severely affected plantings, it may be worth replanting the damaged areas with spring garlic or other crops.

How the Problem Manifests

Waterlogging is one of the most common causes of winter garlic death. It manifests as yellowing, wilting, and subsequent rotting of plants, especially in low-lying areas, on heavy clay soils, and during prolonged rainy periods. Cloves become soft, watery, often with a pinkish or brownish tint, and become covered with mold.

Why This Happens

The cause is soil over-wetting combined with low temperatures. Excess water displaces air from soil pores; the roots and clove suffocate (anaerobiosis sets in). Under such conditions, soil pathogens (fungi of the genera Fusarium, Pythium, Botrytis) become active, causing tissue rot (Engeland, 1991; University of Minnesota, 2024). Waterlogging is especially dangerous during winter thaws and during prolonged spring rains.

Waterlogging is often confused with freezing: externally, plants look the same—they wilt and die. The difference is that with waterlogging, cloves have a characteristic rotten smell, and tissues become watery and soft, whereas with freezing, they simply dry out.

How to Prevent It

Drainage and site selection. Garlic does not tolerate stagnant water. The site should be level or have a slight slope for water runoff. Heavy clay soils require deep digging (at least a spade's depth) and the addition of sand or organic matter to improve structure and water permeability (Engeland, 1991).

Raised beds. In regions with excessive moisture, it is recommended to grow garlic on raised beds 15–25 cm high. This provides drainage and prevents water from stagnating in the root zone.

Choosing planting dates. Early planting in a wet autumn increases the risk of waterlogging, as garlic may begin to grow and become more susceptible to over-wetting. Plant garlic so that it roots but does not have time to grow a large leaf mass.

Mulching with caution. In regions with wet winters, mulch can exacerbate waterlogging by creating a greenhouse effect and retaining moisture. It is recommended to use mulch only in areas with stable snow cover or to use air-permeable materials (e.g., straw, not dense leaves). In rainy winters, it is better to remove the mulch (Engeland, 1991).

What to Do If You Spot It

At the first signs of waterlogging, immediately ensure water drainage—dig drainage ditches, loosen the soil to improve aeration. Remove and destroy (burn) affected plants to prevent the spread of rot. Treat remaining plants with copper-based fungicides or products containing Trichoderma to suppress pathogens. In conditions of excessive moisture, dusting the soil with wood ash is effective—it dries and disinfects.

How the Problem Manifests

Instead of a multi-cloved bulb, a single round bulb grows—a round (single-clove bulb). It can be as small as a pea or as large as an onion bulb. Externally, it resembles an undivided head, but when cut open, it is clear that cloves have not formed.

Why This Happens

A single-clove bulb is a normal stage of garlic development from bulbils (aerial bulbs) or from very small cloves. When bulbils are planted, single-clove bulbs always form in the first year, which divide into full heads in the second year (Engeland, 1991; University of Minnesota, 2024).

However, single-clove bulbs can also form from normal cloves for several reasons:

1. Lack of cold exposure (vernalization). For the head to divide into cloves, garlic requires a period of low temperatures (vernalization). If the winter was too warm or the garlic was planted too late and did not receive sufficient cooling, division may not occur. Winter varieties are particularly sensitive to this (Rabinowitch & Kamenetsky Goldstein, 2020; Engeland, 1991).

2. Spring planting. Spring garlic planted in spring often forms single-clove bulbs if it was not pre-cooled. For spring varieties, pre-planting cooling of cloves in the refrigerator for 2–3 weeks at +2…+5 °C is recommended.

3. Too small planting material. Small cloves (less than 2–3 g) and bulbils do not have enough nutrient reserves to form a multi-cloved head in the first year (Engeland, 1991; University of Minnesota, 2024).

4. Unfavorable growing conditions during clove formation. Drought, nutrient deficiency, leaf damage in May–June can "confuse" the plant's physiological signals, causing it to finish its growing season as a single-clove bulb instead of forming cloves.

How to Prevent It

Choice of planting material. To obtain large multi-cloved heads, use only large, healthy cloves weighing at least 5–6 g. Small cloves are left for growing single-clove bulbs (which are then used as planting material).

Ensuring vernalization. In regions with mild winters, where the cold period is insufficient for vernalization, cloves can be kept at +2…+5 °C for 4–6 weeks before planting. This is especially important for spring varieties (Engeland, 1991).

Planting dates. Winter garlic is planted in autumn to receive full cold exposure. Spring garlic is planted in spring, but with mandatory pre-planting preparation (cooling).

Optimal growing conditions. During the clove formation period (for winter garlic — May–June), regular watering and adequate nutrition, especially phosphorus and potassium, are important. Nitrogen fertilizing is reduced at this time to avoid stimulating leaf growth at the expense of head formation.

What to Do If Single-Clove Bulbs Appear

Single-clove bulbs are not a lost crop. They can be eaten (they are often more tender and less pungent) or saved for planting in the next season. When planted, single-clove bulbs usually produce large multi-cloved heads, so they can be used as valuable planting material. Store single-clove bulbs the same way as regular garlic.

How the Problem Manifests

Garlic bulbs grow significantly smaller than the expected size for the variety. Instead of large, dense bulbs, you get small ones, sometimes no larger than a walnut.

Why This Happens

A small bulb results from limited photosynthesis or insufficient resources during the active growth period (spring – early summer). The main reasons are:

1. Nutrient deficiency. Garlic is a crop with high requirements for nitrogen, phosphorus, and potassium. Nitrogen is especially critical during the active leaf growth phase (spring). With its deficiency, plants are stunted, leaves are small and pale, limiting photosynthesis and carbohydrate accumulation in the bulb (Engeland, 1991; Rabinowitch & Kamenetsky Goldstein, 2020).

2. Lack of moisture. Drought in May–June (the period of bulb formation and filling) sharply reduces yield. Without sufficient water, the plant cannot increase biomass, and the bulb remains small.

3. Dense plantings. With too frequent planting, plants compete for light, water, and nutrients. Bulbs are small, even if the soil is fertile. The optimal distance between cloves is 8–10 cm in the row (Engeland, 1991; University of Minnesota, 2024).

4. Leaf damage. Diseases (e.g., rust), pests (thrips, onion fly), and mechanical damage to leaves reduce photosynthetic activity. Even removing scapes (flower stalks) at the wrong time can reduce bulb size.

5. Disrupted planting dates. Too late planting of winter garlic leads to poor rooting and low winter hardiness. Too early planting of spring garlic leads to stretching and weakening of plants before optimal conditions arrive (Engeland, 1991).

6. Variety degeneration. With prolonged vegetative propagation (without renewal through bulbils or changing planting material), garlic can gradually become smaller due to virus accumulation and reduced genetic viability.

How to Prevent It

Balanced nutrition. In autumn, add manure humus or compost (1–2 buckets per 1 m²) and complete mineral fertilizer (nitroammophoska — 30–40 g/m²) for digging. In spring, after emergence, apply a nitrogen fertilizer (urea — 15–20 g/m²). During the active growth phase (end of May), apply potassium-phosphorus fertilizers (superphosphate + potassium sulfate, 15–20 g/m² each) (Engeland, 1991).

Regular watering. In May–June, if the weather is dry, water garlic 1–2 times a week, soaking the soil to a depth of 15–20 cm. Stop watering 2–3 weeks before harvest.

Optimal planting density. Large cloves are planted at 10×20 cm spacing (10 cm between cloves, 20 cm between rows). Small cloves and bulbils are planted denser. For large-headed varieties, the in-row distance can be increased to 12–15 cm.

Leaf protection. Timely control of diseases and pests. For bolting varieties, remove scapes when the scape just begins to curl, but no later, otherwise some nutrients will be lost (Engeland, 1991).

Renewal of planting material. Every 3–4 years, it is recommended to renew the variety by growing garlic from bulbils. This "rejuvenates" the crop and restores bulb size.

What to Do If Bulbs Are Already Small

Use them in food like regular garlic, but note that the storage ability of small bulbs may be lower. They are not used for planting, except when you need to grow single-clove bulbs or renew the variety through bulbils.

How the Problem Manifests

Cloves in the bulb are loosely packed, with gaps visible between them; the bulb easily falls apart when pressed. Externally, the bulb appears "loose," even if the cloves are large. Such bulbs often have a thickened neck or even remnants of green leaves in the center.

Why This Happens

Loosening of the bulb results from an incomplete bulb formation process. Normally, garlic first grows leaf mass, then forms cloves, and at the end of the growing season, accumulated carbohydrates flow from the leaves and roots into the bulb, making it dense. If this process is disrupted, the bulb remains loose (Engeland, 1991; Rabinowitch & Kamenetsky Goldstein, 2020).

Main causes:

1. Excess nitrogen during the bulb formation period. Nitrogen stimulates leaf and root growth but delays carbohydrate outflow to the bulb. As a result, leaves remain green, and the bulb does not have time to "fill" and become dense. This is one of the most common causes of loose bulbs (Engeland, 1991).

2. Excess moisture at the end of the growing season. If June–July is rainy, or watering is stopped too late, the bulb does not have time to dry and compact; cloves remain loose (Engeland, 1991).

3. Lack of potassium and phosphorus. These elements are necessary for the outflow of carbohydrates from leaves to storage organs. With their deficiency, the bulb forms but remains loose.

4. Too early harvesting. If garlic is harvested before the bulb "filling" process is complete (when leaves are still fully green), the bulb will not have time to compact (Engeland, 1991; University of Minnesota, 2024).

5. Lack of heat. For full maturation, garlic requires a certain sum of active temperatures. In a cool summer, bulbs may remain loose.

6. Varietal characteristics. Some varieties, especially softnecks, are more prone to forming loose bulbs than hardnecks.

How to Prevent It

Proper nutrition. In spring — nitrogen fertilizing. At the end of May – beginning of June — potassium-phosphorus (superphosphate, potassium sulfate). From mid-June, nitrogen fertilizing is completely stopped.

Stop watering. Stop watering 2–3 weeks before harvest. This stimulates carbohydrate outflow from leaves to the bulb and its compaction.

Correct harvest timing. Harvest garlic when the plants have 4–5 green leaves left, and the lower leaves begin to yellow and dry. The bulb neck at this point should be soft. Harvest in dry weather (Engeland, 1991; University of Minnesota, 2024).

Drying after harvest. After harvest, garlic must be dried thoroughly. Optimal regime: 1–2 weeks at +25…+30 °C in a well-ventilated area (or under a canopy), then another 2–3 weeks at +20…+25 °C. During drying, the bulbs mature and compact.

What to Do If Bulbs Are Already Loose

Such bulbs store worse and are more susceptible to diseases. They should be used first. In the next season, adjust the fertilizing and watering regimen.

How the Problem Manifests

The outer skins of the bulb crack, exposing the cloves. The bulb loses its marketable appearance, cloves separate easily, and the outer skins peel away. Cracking is often accompanied by darkening or rotting of the cloves.

Why This Happens

Cracking of the outer skins is a sign of over-maturity of the bulb. When garlic stays in the ground longer than the optimal time, the cloves continue to grow, pushing the outer skins apart. The outer skins, which by this time have dried out and lost elasticity, cannot withstand the pressure and burst (Engeland, 1991; University of Minnesota, 2024). This process resembles a flower "opening": the bulb opens up, and cloves spread apart.

Other causes:

1. Sharp fluctuations in moisture. If a dry period is followed by abundant rain, the cloves begin to actively fill, which can cause the dried skins to rupture.

2. Excess nitrogen. Nitrogen stimulates clove growth, even during the period when they should have stopped growing.

3. Varietal characteristics. Some varieties are more prone to cracking, especially when left in the ground too long.

4. Storage regime violation. When stored in conditions with sharp moisture fluctuations (e.g., after prolonged dryness followed by humidification), the outer skins may crack.

How to Prevent It

Observing harvest timing. Harvest garlic when the plants have 4–5 green leaves left, and the lower leaves begin to yellow and dry. Indicator: the outer skins of the bulb should be dry and light, but not overly dry. Do not over-keep garlic in the ground! In wet summers, the risk of cracking increases, so harvest earlier (Engeland, 1991; University of Minnesota, 2024).

Stop watering. Stop watering 2–3 weeks before harvest to prevent rapid clove growth just before harvesting.

Proper storage. Store garlic at 0…+4 °C and 60–70% humidity. Sharp fluctuations in humidity are unacceptable.

What to Do If Skins Have Cracked

Cracked bulbs store poorly—fungi and bacteria enter through the cracks. They should be used first: for food, processing, or planting (if cracks are small and cloves are not damaged). Large cracks make the bulb unsuitable for long-term storage.

How the Problem Manifests

Cloves in the bulb start growing before planting (in autumn) or much earlier than expected (in winter, early spring). Green sprouts appear on the cloves, sometimes up to 5–10 cm long. Such cloves, when planted, produce weak plants or do not root at all.

Why This Happens

Garlic sprouting is controlled by temperature and humidity. The main cause of premature sprouting is storage at +5…+12 °C. It is precisely at this temperature that garlic "wakes up" and begins active growth (Engeland, 1991; Rabinowitch & Kamenetsky Goldstein, 2020). Moreover, sprouting does not start immediately, but after a certain period of heat accumulation.

The second factor is high humidity. At humidity above 70–75%, even at unfavorable temperatures, the sprouting process can accelerate. Hardneck varieties are particularly sensitive to this and store less well than softnecks (Engeland, 1991).

The third cause is physiological immaturity of the bulbs. Garlic harvested too early has not completed the full "dormancy" cycle and sprouts faster during storage.

How to Prevent It

Correct storage conditions. The optimal regime for storing culinary garlic: 0…+4 °C, humidity 60–70%. Under these conditions, garlic remains in deep dormancy and does not sprout for 6–8 months (Engeland, 1991; University of Minnesota, 2024).

For planting material — a different approach. If garlic is intended for planting, store it at +18…+20 °C (room temperature). At this temperature, dormancy is maintained longer, and cloves do not sprout prematurely. 2–3 weeks before planting, move them to a cool place (+2…+5 °C) for vernalization (Engeland, 1991). Storing seed garlic at +5…+12 °C is unacceptable — it will sprout before planting.

Timely harvesting. Garlic for storage is harvested only after full maturity: when leaves are 50–60% yellow, the neck is soft, and bulbs are firm.

Ventilation. The storage area must be well ventilated to avoid stagnant humid air. Humidity should not exceed 70%.

What to Do If Cloves Have Sprouted

Sprouted cloves can be used for planting (if sprouts are not too long — up to 3–5 cm), but the yield will be lower. Sprouted garlic does not store well: it should either be used immediately in food or processed. Cloves with long sprouts (more than 5 cm) are unsuitable for planting—they will produce weak, non-viable plants.

How the Problem Manifests

Garlic that should store well begins to spoil 2–3 months after harvest: it dries out, shrivels, rots, or sprouts. Storage ability is the capacity of garlic to maintain its quality over a long period (Engeland, 1991).

Why This Happens

Storage ability depends on a combination of factors:

1. Varietal characteristics. Softneck (non-bolting) garlic varieties generally store longer than hardnecks (Engeland, 1991). Among hardnecks, the most storable are varieties from the Porcelain group, and the least are Rocambole.

2. Growing conditions. Garlic grown on excessively nitrogen-rich soils (or with abundant nitrogen fertilizing) stores less well. It is juicier, with a loose bulb and thin outer skins. Garlic grown on well-balanced soils (with sufficient potassium and phosphorus) has denser bulbs and stores better (Engeland, 1991).

3. Weather conditions during maturation. Rainy weather before harvest reduces storage ability: bulbs accumulate moisture and are more quickly affected by diseases.

4. Harvest timing and quality. Garlic left too long in the ground loses storage ability (bulbs crack, cloves may sprout). Immature garlic also stores poorly—it is insufficiently dry, and the outer skins are weak.

5. Storage conditions. As noted, temperature (0…+4 °C) and humidity (60–70%) are crucial for garlic storage. Violation of these parameters sharply reduces storage ability.

6. Damage during harvest. Mechanical damage (bruises, scratches, tearing of roots) — entry points for infections, reducing storage ability (Engeland, 1991).

How to Prevent It

Variety selection. For long-term storage, choose storable varieties (softnecks like 'Silverskin', 'Artichoke', and among hardnecks, varieties from the Porcelain group). Varieties from the Rocambole and Continental groups store less well (Engeland, 1991).

Balanced nutrition. In autumn — phosphorus-potassium fertilizers. In spring — nitrogen in moderate amounts. Potassium and phosphorus improve storage ability.

Proper harvesting. Harvest garlic only in dry weather, when leaves are mature. Do not pull garlic from the ground—dig it up, using a fork, to avoid damaging the bulb. After harvest — thorough drying for 2–3 weeks.

Storage conditions. Before storage, grade the garlic: large bulbs for long-term storage, small and damaged ones for immediate use. Optimal conditions: 0…+4 °C, humidity 60–70%, good ventilation. Do not store garlic near vegetables that emit ethylene (apples, pears)—this stimulates sprouting (Engeland, 1991).

What to Do If Storage Ability is Lost

Garlic with reduced storage ability (soft, shriveled, with signs of sprouting) should be processed: dried, frozen, used for making garlic pastes, oils, pickles. Do not use it for planting.

How the Problem Manifests

Instead of one large, dense bulb, several smaller bulbs connected by a common neck are formed, or many small cloves arranged around the central part. The bulb seems to "fall apart" into separate parts or has a highly deformed structure. Proliferation is often confused with loosening, but unlike the latter, proliferation involves the formation of additional growth points, not just weak clove attachment.

Why This Happens

Proliferation is a disruption of apical dominance. Normally, the apical bud (growing point) suppresses the development of lateral buds. When the apical bud is damaged or hormonal balance is disturbed, lateral buds begin to actively develop, forming a "nest" of small bulbs or double, triple cloves (Engeland, 1991).

Main causes:

1. Damage to the growing point. Mechanical (e.g., during deep cultivation) or frost damage. If the growing point is damaged, the plant "awakens" lateral buds.

2. Sharp temperature fluctuations. Late spring frosts are especially dangerous when garlic has already started to grow. Frost can damage the central bud, leading to the formation of several replacement bulbs.

3. Lack of moisture during the critical period. Drought during the clove formation phase can disrupt cell division and lead to proliferation.

4. Varietal characteristics. Varieties with a high tendency to form double cloves, such as some Rocamboles, more often produce proliferation than others (Engeland, 1991).

5. Using overly large cloves. Large cloves with a large nutrient reserve can produce several shoots (double cloves), manifesting as proliferation.

How to Prevent It

Preserving the growing point. Avoid deep cultivation near plants in spring. Protection from frost (covering with agrotextile, mulching) is critical in regions with return frosts.

Stable watering. During the clove formation phase (May–June), the soil should be moist but not waterlogged. Sharp fluctuations in moisture should be avoided.

Variety selection. For growing in areas with unstable weather, choose varieties less prone to proliferation. A variety's resistance to proliferation can only be assessed by trial—observe the variety's behavior in your conditions.

Calibration of planting material. Do not use double cloves or cloves that produce multiple shoots for planting. When selecting planting material, carefully inspect the cloves—exclude those that show several growth points (Engeland, 1991).

What to Do If Proliferation Occurs

The harvest from proliferated bulbs can be used for food (all parts are edible), but their storage ability is low. Such bulbs do not store well—process them or use immediately. They are unsuitable for planting—proliferation may repeat in the next generation.