Care

Loosening: Why and How Often

Loosening is not just about killing weeds. It serves three important functions:

1. Improves gas exchange — zucchini roots need oxygen no less than leaves need carbon dioxide. In dense, crusted soil that has settled after rain, roots suffocate, absorptive capacity drops, and the plant begins to starve even when fertiliser is present (Karataev and Sovetkina, 1984).

2. Breaks capillaries — after loosening, moisture from deeper layers stops evaporating intensively through soil channels. This is a kind of “dry irrigation” that saves water.

3. Creates a fine crumb structure — in such soil, seeds and roots have better contact with soil particles and absorb nutrients more quickly.

Practical recommendations:

• The first loosening is carried out immediately after sowing or planting seedlings, as soon as the rows become visible (Lebedeva, 1987). Depth: 4–6 cm, so as not to damage germinating seeds.
• Subsequent loosening is done after each watering or rain, when the soil has dried out a little (but not completely). The depth is gradually increased to 8–12 cm as plants grow (Kotov and Adritskaya, 2016).
• When the zucchini leaves close in the rows (about 30–40 days after sowing), loosening is stopped—the plants themselves shade the soil and suppress weeds. By this time, the main soil work should be completed.

Important warning: do not loosen deeply near the stem itself—zucchini roots are close to the surface and are easily damaged. Leave a stem circle of radius 10–15 cm untouched, and loosen only between rows.

Combating Soil Crust

Crust is a dense layer on the soil surface that forms after heavy rain or watering, when water evaporates quickly and pulls fine particles together. Crust:

• Hinders seed germination—young shoots cannot break through the hard film (Pantielev, 1986);
• Blocks air access to roots, weakening them;
• Increases evaporation of moisture from deeper layers, as capillaries in the crust act like a wick.

What to do:

• Fight crust before emergence. If heavy rain has fallen after sowing and a crust has formed, break it by light harrowing with a rake across the rows or by light watering (80–90 m³/ha)—water softens the crust and allows seedlings to emerge (Pantielev, 1986).
• During active growth — regular loosening (see above) prevents crust formation. Ideally, loosen the soil every 5–7 days after each wetting.
• Prevention: mulching (see below) almost completely solves the crust problem, because the mulch absorbs the impact of raindrops and prevents surface compaction.

Mulching — Your Best Ally

Mulching is covering the soil with organic or synthetic materials. For zucchini, mulch offers several advantages at once:

1. Retains moisture — evaporation from the surface is reduced by 30–50%, which is especially valuable in hot summers. Roots receive water more evenly, without stress fluctuations.

2. Suppresses weeds — light does not reach weed seeds, and they do not germinate. This reduces manual weeding many times over.

3. Prevents crust formation — soil under mulch remains loose and structural.

4. Protects fruits from rot — zucchinis do not lie on bare wet soil but come into contact with dry mulch or film, reducing the risk of bacterial and fungal diseases (Nonnecke, 1989).

5. Improves thermal regime — black mulch (film or dark material) absorbs solar heat and warms the soil, accelerating plant development in cool weather (Wehner et al., 2020).

Types of mulch and their features:

• Black polyethylene film — the most popular option for commercial growing and serious gardeners. It warms the soil well, completely suppresses weeds, and retains moisture. Drawback: the film must be laid before planting (or holes cut for seeds/seedlings), and in autumn it must be removed. Also, under the film, the soil can overheat in hot regions—then it is better to use reflective or perforated film (Wehner et al., 2020).
• Straw, hay, grass — excellent organic matter that gradually decomposes and fertilises the soil. The layer should be at least 5–8 cm to effectively suppress weeds. Important: do not use freshly cut grass with seeds—otherwise you will get not mulch but a weed nursery. Pre‑wilted, slightly dried grass is preferable.
• Compost, well‑rotted manure — this is both mulch and fertiliser. A 3–5 cm layer around plants feeds, retains moisture, and improves soil structure.
• Sawdust, wood chips — good for between rows but not for the stem circle, as they can acidify the soil during decomposition. Use only well‑rotted sawdust.

Practical tip: in the Non‑Black Earth region with its cool climate, black film gives the best results for early harvests. In southern regions, where temperatures often exceed 30 °C, it is better to use light mulch (straw, hay) to avoid overheating the roots.

Weed Control: Strategy and Tactics

Zucchini, especially in the first 3–4 weeks after emergence, grows slowly and cannot compete with fast‑growing weeds. If you do not control them from the start, weeds will “suffocate” the crop, stealing light, moisture, and nutrients. At the same time, herbicides are rarely used for zucchini—the crop is sensitive to them (Autko et al., 2012; Wehner et al., 2020). Therefore, the main emphasis is on agronomic methods.

Main techniques:

1. Mechanical weeding — loosening between rows with a cultivator or hoe (by hand in the rows). The first weeding is combined with thinning the seedlings, leaving one, strongest plant per nest (Lebedeva, 1987). The second—after 10–14 days. By the time the leaves close (after 40–50 days), the zucchini already suppresses weeds with its own shade.

2. “Clean sowing” (provocation method) — 10–15 days before sowing zucchini, water the plot and allow weeds to emerge. Then carefully cut them off with a flat cutter at a depth of 2–3 cm, without turning the sod. Sow crop seeds into this prepared, weed‑cleared soil. Weeds that emerge later will not be so numerous and can be easily removed with the first loosenings (Nonnecke, 1989).

3. Mulching — we have already mentioned this. This is the most reliable and low‑cost way to keep the bed clean.

4. Manual weeding in rows — is essential, because between plants in a row (especially if sown with 50–70 cm spacing), weeds can break through that the hoe cannot reach. Remove them while they are small—adult weeds are pulled out with their roots and can damage the zucchini root system.

Important: if you use herbicides (e.g., trifluralin—approved for zucchini in some countries), strictly follow the instructions and never apply them after emergence or on plants intended for consumption with young skin. In a home garden, it is better to abandon chemicals altogether in favour of mulch and manual weeding.

Removing Old and Diseased Leaves

Zucchini ages from the bottom up: the first leaves, formed right at the ground, turn yellow, lose turgor, and after 30–40 days become useless for photosynthesis (Karataev and Sovetkina, 1984). They not only do not work but also hinder:

• They shade the soil, creating dampness and provoking fungal diseases;
• They touch wet ground and quickly rot;
• They prevent ventilation of the lower tier, where powdery mildew and grey mould most often begin.

What and how to remove:

• Remove all leaves that have turned yellow, become spotted, dried out, or are simply lying on the ground and beginning to rot.
• Cut leaves with a sharp knife or secateurs at the very base, leaving a stump of no more than 1–2 cm—do not tear them off by hand, so as not to damage the stem (Wehner et al., 2020).
• During the season, carry out sanitary pruning once every 1–2 weeks, especially after rains when humidity is high. In hot, dry weather, this can be done less often.
• Remove no more than 2–3 lower leaves at a time, so as not to weaken the plant abruptly. Step‑by‑step removal is less stressful.

As a result, the lower part of the bush becomes “aerated,” sunlight penetrates deeper, warming the soil, and access to the ovaries for bees improves. According to Autko et al. (2012), regular removal of lower leaves in greenhouses and tunnels reduces the incidence of grey mould by 30–50%.

Thinning Dense Bushes

In zucchini, especially old ones or those planted too close together, many side shoots and leaves develop, overlapping each other. Overcrowding leads to:

• Reduced photosynthesis (each leaf receives less light);
• Poorer pollination (bees cannot reach flowers in dense foliage);
• Increased humidity inside the bush—ideal conditions for powdery mildew and anthracnose (Nonnecke, 1989).

How to thin:

• In bush varieties (most modern zucchinis are bush types), remove side shoots if there are too many. Leave 3–4 of the strongest, cut out the rest.
• Also remove leaves that grow inward, cross, or rub against each other—they receive no light and serve only as shelter for pests.
• Leave at least 70 cm between plants (for bush types) and 1–1.5 m (for trailing types)—this is basic prevention of overcrowding (Welbaum, 2015).

Sanitary Pruning: Removing Everything Unnecessary

In addition to old leaves, remove:

• Flowers that have not set fruit (especially male flowers after flowering)—they only consume resources.
• Damaged or misshapen ovaries—they will not grow to marketable condition but will slow the formation of new ones (Kotov and Adritskaya, 2016).
• Tendrils and side shoots in varieties that produce them, if they are not needed for shaping the bush (bush varieties have almost no tendrils).

Regular sanitary pruning not only improves plant health but also redirects nutrients to the ovaries and young fruits, increasing their size and number.

Care Features for Bush and Trailing Varieties

Most modern zucchini varieties are bush‑type—compact, with short internodes, ideal for small plots. However, trailing forms also exist (e.g., the old variety “Gribovskie”), as well as zucchini‑type varieties with semi‑trailing habits.

Bush varieties:

• No shaping is needed—they grow as dense bushes on their own.
• The main task is to remove lower old leaves and ensure the bush does not become too dense.
• If overcrowded, a few central leaves can be removed to allow light to reach the ovaries.

Trailing varieties and zucchinis:

• If a variety produces long vines (more than 1.5 m), they can be directed along the bed, pinned to the ground in several places for rooting—this gives additional roots and increases nutrition (Lebedeva, 1987).
• When the vine reaches 2–3 metres, pinch the growing point—this stimulates the growth of side shoots, which produce more female flowers (Karataev and Sovetkina, 1984).
• Trailing forms are best grown on trellises or nets to save space and improve light exposure.

Using Supports and Vertical Growing

Although zucchini traditionally sprawls on the ground, vertical growing on supports offers several advantages, especially for long‑vined varieties and small plots:

• Fruits do not touch the ground, eliminating rotting and slug damage.
• Ventilation and lighting improve, reducing the risk of powdery mildew.
• Space is saved—vines can be run up a trellis 1.5–2 m high (Wehner et al., 2020).
• Harvesting is easier—all fruits are visible, without having to push leaves aside.

How to set up vertical growing:

• Install sturdy supports (wooden stakes, metal poles, or wire mesh) along the row.
• As the vine grows, tie it to the support with soft twine (not too tight, so as not to constrict the stem).
• Remove side shoots, leaving 2–3 main ones so as not to overload the support.
• For bush varieties, vertical growing is not suitable—they do not climb and have rigid upright stems that may break under the weight of the fruit.

Important: fruits on vertically grown zucchinis may stretch under their own weight, but for most varieties this is not critical. The main thing is to tie up the stem, not the fruit itself, so that the load is distributed evenly.

Why Regular Harvesting Stimulates New Ovaries

At the heart of this is the principle of dominance of “strong sinks.” In zucchini, as in other cucurbits, nutrients (assimilates) are distributed among growing fruits by competition. The largest fruit becomes the main “sink”: it draws the bulk of sugars, minerals, and water that could have gone to the formation of new ovaries (Nonnecke, 1989). The plant “invests” in the fruits that have already set and temporarily slows the formation of new flowers and ovaries.

This is an evolutionary mechanism: the seeds in the maturing fruit must receive maximum resources for survival. But for the gardener, this means that if you leave an overgrown zucchini on the bush, new fruits will not set, or will be small and misshapen. Conversely, removing the fruit removes dominance, and the plant immediately directs the freed resources to the formation of new flowers and ovaries.

How this works in practice:

• At the start of fruiting (the first wave), usually 2–3 fruits set. They should be harvested as soon as they reach picking size.
• After that, the plant “switches on” a second wave of flowering, and the process repeats.
• With regular harvesting, zucchini fruits continuously until the first frosts (Lebedeva, 1987).

What Happens When Fruits Overgrow

An overgrown zucchini is not just a loss of eating quality. It is a signal to the plant to “complete its mission” and switch to seed maturation. As soon as the fruit reaches biological maturity (skin hardens, seeds become large), the plant begins to slow the formation of new flowers and then stops flowering altogether.

Moreover, overgrown fruits:

• Divert nutrients that could have gone to new ovaries;
• Increase the load on the root system and leaf apparatus, accelerating bush ageing;
• Begin to rot with prolonged contact with the soil, becoming a source of infection.

Therefore, never leave fruits on the bush that have outgrown marketable size, even if you do not plan to eat them—it is better to cut them off and put them in compost (or use them for animal feed if large). This is prevention of fruiting stagnation.

Optimum Harvesting Frequency

At the peak of fruiting (July–August), zucchinis should be harvested at least once every 2–3 days (Welbaum, 2015). In hot weather, fruits fill faster, and the interval may shorten to 1–2 days. With less frequent picking, you risk:

• losing part of the harvest due to over‑ripening;
• reducing the overall productivity of the bush.

Approximate harvest times for different purposes:

In most cases, for everyday use, it is best to harvest zucchinis 15–20 cm long—they have not yet lost tenderness but have already gained sufficient weight (Karataev and Sovetkina, 1984).

Practical tip: cut the fruit together with its stalk (leave 2–3 cm) so as not to damage the plant itself. Do not break off the fruit—this can injure the stem and open the door to infection.

Growing for Young vs. Mature Fruits

For continuous production of young zucchinis (green fruits) — follow the rule of regular harvesting and do not allow over‑ripening. If you notice a fruit starting to turn yellow or the skin becoming hard, remove it, even if it is not fit to eat.

For producing mature fruits (for winter storage or seed):

• Do not leave more than 2–3 fruits per bush to mature—otherwise they will be small.
• Remove all other ovaries so that nutrition goes only to these fruits.
• Maturation time is 30–40 days after pollination. Sign of readiness: the skin becomes hard (cannot be pressed with a fingernail), and the stalk begins to dry (Nonnecke, 1989).

Note: zucchinis grown for mature fruits are usually of winter varieties (e.g., ‘Spaghetti’, ‘Bush Orange’). Most summer varieties are not intended for storage—they should be used fresh.

Summary: Manage Fruiting Through Harvesting

Fruiting management is a simple and effective tool. The main rules:

1. Harvest fruits every 2–3 days.

2. Do not allow over‑ripening—cut off and remove overgrown fruits from the bed.

3. Cut fruits with part of the stalk, without breaking.

4. For winter storage, leave no more than 2–3 fruits per bush and allow them to fully ripen.

Following these simple rules guarantees that your zucchini will fruit until the cold weather, and fresh fruits will delight you all summer and autumn.

Protection from Overheating

At temperatures above 30–32 °C, zucchini begins to experience serious problems:

• Pollen becomes sterile — pollination fails, ovaries drop (Welbaum, 2015).
• Stomata close — photosynthesis slows, the plant switches to survival mode.
• Leaves lose turgor even when the soil is moist—roots cannot supply water fast enough because of high transpiration.
• Fruits become smaller and over‑ripen faster.

How to protect from overheating:

1. Light‑coloured mulch. In hot regions, use straw, hay, light grass, or white non‑woven fabric. Dark film overheats the soil, which can harm roots. Light mulch reflects sunlight and keeps the soil cool.

2. Shading during the hottest hours. If you have a prolonged period with temperatures above 35 °C, install a light covering material (agrotextile, gauze, fine netting) over the bed at a height of 0.5–1 m. It should provide shade but not complete darkness—30–50% shading is enough to reduce the temperature by a few degrees and protect flowers from sterility (Wehner et al., 2020).

3. Watering in the morning. If you water zucchinis during the day in heat, water can burn the leaves (lens effect). Morning watering allows plants to stock up on moisture before noon and tolerate high temperatures better.

4. Removing lower leaves to improve air circulation (as we already discussed in Chapter 3). Stagnant hot air inside the bush is even more dangerous than just heat.

Protection from Cold Nights

Zucchini does not tolerate temperatures below 10 °C well. During prolonged cold spells:

• Root growth slows — they stop efficiently absorbing water and nutrients.
• Formation of female flowers is suppressed — only male flowers form on the plant, reducing yield (Kotov and Adritskaya, 2016).
• Young ovaries may die from cold stress.

How to protect from cold nights:

1. Temporary covers. Early in the season, when return frosts are still possible, use film tunnels or non‑woven fabric covers. On cold nights, cover the plants in the evening and remove in the morning when the temperature rises above 15 °C. On especially cold nights, you can add a second layer (spunbond + film), but be careful not to overheat under the sun during the day.

2. Hot beds. If you plant zucchinis on a bed filled with well‑rotted manure or compost (layer 20–30 cm), biological heat will warm the roots even when air temperatures are low. This is especially relevant for regions with cool summers (Lebedeva, 1987).

3. Choosing varieties. In regions with short, cool summers, prefer cold‑hardy varieties (e.g., ‘Aeronaut’, ‘Beloplodny’)—they are less sensitive to cold.

4. South‑facing slopes and wind protection. Planting on a south‑facing slope or against a house wall provides additional heat from solar warming. Protection from cold northerly winds (windbreak plantings of corn or sunflower) also helps retain heat (Nonnecke, 1989).

Effect of Air Humidity

For zucchinis, especially during flowering and fruit set, air humidity is crucial:

• At high humidity (over 80%), pollen clumps together and is poorly carried by wind and insects, making pollination ineffective. In addition, high humidity creates ideal conditions for powdery mildew, grey mould, and anthracnose (Welbaum, 2015).
• At low humidity (below 50%), pollen dries out on the flowers before bees can transfer it. Ovaries may fail to form, and already set fruits stop growing.

What to do:

• Water at the root, without splashing water on the leaves. Overhead watering increases air humidity and can provoke disease. Use drip irrigation or a watering can without a sprayer, directing water strictly to the soil.
• In very dry weather (humidity below 40%), you can slightly moisten the air around the plants by watering the paths or placing open containers of water near the beds. But this should be done only in hot, dry weather when fungal diseases are not threatened by dampness.
• In rainy periods, when humidity is high, the priority is ventilation (see below). Regularly remove lower leaves to allow air to circulate freely.

Ensuring Good Ventilation of Plantings

Stagnant, humid air is the main enemy of zucchinis. Even without rain, if there is no air movement in dense foliage, condensation forms in the morning and evening, which is a launching pad for fungal infections. Powdery mildew appears precisely in such conditions (Nonnecke, 1989).

Practical techniques for improving ventilation:

1. Correct planting distance. For bush varieties—70×70 cm or 70×100 cm; for trailing types—at least 140×140 cm (Welbaum, 2015). Do not skimp on space—crowded plantings are poorly ventilated.

2. Regular removal of lower old leaves (see Chapter 3). This is the most effective way to open access for air to the root zone.

3. Removing excess side shoots on trailing varieties. Leave 2–3 main shoots, remove the rest.

4. Growing on trellises (for trailing forms) or on ridges that are well blown by the wind. Do not place zucchinis in low spots where air stagnates.

5. Ventilating covers. If you use film tunnels or greenhouses, be sure to leave access for air—open the ends or make ventilation holes. In sunny weather without ventilation, the temperature inside the cover can rise to 40–45 °C, which is fatal for plants (Karataev and Sovetkina, 1984).

Brief Summary on Microclimate

• Heat above 30 °C: shade, mulch with light materials, water in the morning.
• Cold below 10 °C: use covers, hot beds, and choose south‑facing slopes.
• High humidity: water at the root, remove excess leaves, ensure ventilation.
• Low humidity: slightly moisten the air in extreme heat, but do not overdo it.
• Ventilation: correct planting, removal of old leaves, and ventilating covers are the keys to health.

1. Growth Rate and Overall Dynamics

Zucchini is one of the fastest‑growing vegetables. Under favourable conditions, the increase in new leaves and fruits is noticeable in just a day or two. If you notice that:

• Growth has slowed — leaves become smaller, new shoots do not appear, fruits do not increase in size for a long time—this is the first signal of stress. Causes may be different: lack of moisture, nutrition, overheating, stagnant air, onset of disease. You need to check all the other items on this list.
• The plant looks wilted even in the morning — possibly the roots are damaged (e.g., waterlogging or soil pests). In heat, slight wilting at noon is normal, but if it persists until evening and repeats in the morning—it is a problem (Welbaum, 2015).

2. Leaf Colour as a Nutrition Indicator

The colour and condition of leaves are the most obvious indicators of plant health. Different changes in colour indicate different problems:

• Dark green, “fat” leaves with excessive growth — excess nitrogen. This promotes vegetative mass at the expense of flowering and fruiting. Reduce nitrogen fertilisation, add phosphorus and potassium (Wehner et al., 2020).
• Light green, pale leaves, especially lower ones — nitrogen deficiency. Apply a compound fertiliser with nitrogen or organic matter (manure slurry, herbal tea).
• Yellowing leaf margins (marginal chlorosis) — often indicates potassium deficiency. Especially critical for fruiting plants. Apply potassium fertiliser (potassium sulphate, wood ash).
• Yellowing between veins (upper leaves) — lack of magnesium or iron. Spray leaves with a weak solution of magnesium sulphate or iron chelate.
• Brown, dry edges and spots — can be sunburn (if the leaf was wet under direct rays) or a sign of bacterial or fungal infection. Examine the spots: if they are vague, with a yellow border—most likely disease (Nonnecke, 1989).

Important: natural yellowing and dieback of lower old leaves is a normal ageing process. However, if young leaves turn yellow or yellowing spreads rapidly upwards—that is an alarm signal.

3. Flowering and Ovary Formation

Flowering is the basis of the future harvest. At each inspection, assess:

1. Ratio of male to female flowers. At the beginning of the season, in most varieties, male flowers appear first, then females. If, several weeks after flowering begins, the plant still has only male flowers, stress may be the cause (cold, heat, lack of nutrition). Sometimes a top‑dressing with potassium and phosphorus or treatment with fruit‑set stimulants helps (Kotov and Adritskaya, 2016).

2. Ovary drop. If ovaries turn yellow and dry up without growing, there may be several reasons:

• Insufficient pollination (no bees, or too hot/damp for normal pollination). You can hand‑pollinate—pick a male flower, remove the petals, and touch the anthers to the stigma of the female flower (Welbaum, 2015).
• Overloading the plant with fruit—if there are already large fruits on the bush, new ovaries may drop. Regular harvesting helps (see Chapter 4).
• Lack of nutrients, especially potassium.
• Pest or disease damage (e.g., aphids on flower stalks).

4. Fruit Development

When inspecting, evaluate fruits not only by size but also by appearance:

• Correct shape. If fruits are twisted, with a thickened end or conversely a thin “nose”—this often indicates pollination problems (uneven pollen distribution) or nutrient deficiency (especially boron and potassium). In hot weather, such defects are more common (Nonnecke, 1989).
• Hollowness (internal cavities) — sometimes appears with excess nitrogen or lack of moisture during rapid fruit growth (Wehner et al., 2020).
• Blossom‑end rot (dark tip) — a dark spot at the fruit tip that enlarges and becomes soft. This is not an infection but a physiological disorder caused by calcium deficiency against a background of uneven watering or excess nitrogen. Adjust watering and apply calcium (e.g., calcium nitrate in fertilisation).

5. Signs of Disease

Zucchini diseases mostly appear on leaves, less often on fruits and stems. The most common (Nonnecke, 1989; Autko et al., 2012):

• Powdery mildew. White or greyish coating on the upper side of leaves, easily wiped off with a finger. Over time, leaves turn brown and dry. Most often affects in mid‑ to late summer with high humidity and crowded plantings. At an early stage, remove affected leaves and spray with garlic infusion, whey, or biological products. If widespread—use approved fungicides (but for a home garden, it is better to rely on agronomic measures: leaf removal, improved ventilation).
• Downy mildew (peronospora). Yellow angular spots on the upper side of leaves, and a grey‑purple coating underneath. Unlike true powdery mildew, the coating does not wipe off. The disease is dangerous and progresses quickly. At the first signs, remove affected leaves, spray with copper‑containing preparations (Bordeaux mixture) or biological products.
• Anthracnose. Brown or yellowish spots with a dark border, often with cracks in the centre. Can also affect fruits—they develop sunken, weeping spots. Remove affected parts, ensure ventilation, avoid overhead watering.
• Grey mould. Brown weeping spots on stems and fruits, especially where fruits touch the soil. Remove rotten fruits, place boards or mulch under the rest so they do not lie on the ground.
• Bacteriosis (angular leaf spot). Oily, later browning spots on leaves, often limited by veins. If severe, remove leaves, avoid overhead watering.

At any suspicion of disease, first remove all affected parts (leaves, ovaries, fruits) and burn them (not in compost!). Improve planting ventilation, stop watering on leaves. At an early stage, this often stops development.

6. Signs of Pests

• Aphids. Small green or black insects, usually on the undersides of young leaves and on ovaries. Leaves curl, become covered with sticky honeydew. Can be washed off with a strong jet of water or sprayed with soap solution, ash or garlic infusion. If heavily infested—approved insecticides.
• Spider mites. Very small (almost invisible), but their presence is revealed by fine webbing on the undersides of leaves; leaves turn yellow and dry. Often appear in hot, dry weather. Increasing humidity (spraying with water in the evening) helps, as do acaricides or dandelion/garlic infusion.
• Slugs. Eat young leaves and fruits, leaving a slimy trail. Can be controlled with traps (beer baits, boards), dusting with ash or tobacco dust around plants.
• Cutworm caterpillars and other butterflies. Gnaw stems or eat leaves. Collect by hand; in severe infestations, use biological products (e.g., ‘Lepidoсid’).

7. Weekly Inspection Checklist

Make it a rule to walk through the zucchini beds once a week (at the peak of the season, every 3–4 days) and check according to the following plan:

1. General condition: does the bush look depressed, has growth slowed.

2. Leaves: any yellowing, spots, coating, deformations. Special attention to the lower tier and young leaves.

3. Flowers and ovaries: how many male and female flowers, whether ovaries are dropping, whether bees are present.

4. Fruits: how they are growing, shape correct, no rot, spots or skin damage.

5. Stems and base of the bush: no cracks, rotting, damage.

6. Soil: not too dry, not waterlogged, no cracks or crust.

7. Insects: inspect the underside of leaves and young shoots for aphids, mites, egg masses.

If anything is concerning—do not delay, take action immediately. At an early stage, most problems are solved by simple agronomic techniques: removing affected parts, adjusting watering, improving ventilation, and correcting nutrition.

1. Overcrowded Planting

Mistake: planting zucchinis too close together (less than 50 cm for bush varieties, less than 1 m for trailing) in the hope of getting more yield per unit area.

Why it is bad: crowded plants compete for light, water, and nutrients. They stretch, produce fewer female flowers, and the foliage blocks air access, creating a humid, stagnant microclimate—ideal for powdery mildew and grey mould (Wehner et al., 2020). As a result, the total yield per square metre may be even lower than with proper, spaced placement.

How to avoid:

• For bush varieties, leave at least 70–90 cm between plants in a row and 90–100 cm between rows (Welbaum, 2015).
• For trailing types, at least 120–150 cm between plants.
• If space is limited, choose compact bush varieties rather than trailing ones.
• When growing in containers, use containers of at least 20–30 litres per plant.

2. Irregular Harvesting

Mistake: skipping a harvest for 4–5 days or more, especially at the peak of fruiting. “Let them grow a bit more,” thinks the gardener, and the fruit over‑ripens, becomes tough, and new ovaries stop appearing.

Why it is bad: as we discussed in Chapter 4, an overgrown fruit becomes the main “sink” of nutrients, inhibiting the formation of new ovaries. As a result, the bush produces several overgrown “giants” at once and then stalls for a long time (Nonnecke, 1989).

How to avoid:

• At the peak of fruiting, harvest fruits every 2–3 days.
• Remove even those fruits you do not plan to eat if they have outgrown marketable size (send them to compost).
• Cut fruits carefully, leaving 2–3 cm of stalk.

3. Not Removing Old Leaves

Mistake: leaving all leaves on the bush, even those that have yellowed, dried out, or are lying on the ground. “The plant knows what it needs,” some believe.

Why it is bad: lower old leaves no longer work for photosynthesis, but they create shade and high humidity near the soil surface, provoking fungal diseases. Moreover, they may touch the ground and rot, becoming a source of infection (Autko et al., 2012).

How to avoid:

• Weekly remove all yellowed, dry, spotted, or simply old lower leaves.
• Cut them off at the very base, leaving no long stumps.
• Remove no more than 2–3 leaves at a time, so as not to weaken the plant.

4. Excessive Nitrogen Fertilisation

Mistake: throughout the season, feeding zucchinis only with nitrogen fertilisers (manure slurry, herbal infusion, urea), forgetting about phosphorus and potassium.

Why it is bad: nitrogen stimulates lush foliage growth at the expense of flowering and fruiting. The plant “fats”: leaves are huge, dark green, but there are few flowers, and ovaries drop. In addition, excess nitrogen makes tissues looser, attracting aphids and increasing susceptibility to fungal diseases (Wehner et al., 2020; Welbaum, 2015).

How to avoid:

• At the beginning of growth, apply a balanced fertiliser (NPK roughly 1:1:1).
• From the appearance of the first flowers and during fruiting, emphasise phosphorus‑potassium fertilisers (e.g., potassium sulphate + superphosphate). Nitrogen at this time is minimal.
• Organic fertilisers (manure slurry, herbal tea) are good only in the first half of the growing season.
• If you notice “fatting” (very vigorous dark leaves), stop all nitrogen fertilising for 2–3 weeks.

5. Overhead Watering and Evening Watering

Mistake: watering zucchinis by sprinkling (over the leaves) or late in the evening, when the leaves do not have time to dry before nightfall.

Why it is bad: wet leaves at night are the main cause of powdery mildew, downy mildew, and other fungal diseases. Fungal spores germinate precisely in water droplets on the leaf surface (Nonnecke, 1989). Watering over the leaves also reduces pollination efficiency by washing off pollen.

How to avoid:

• Water zucchinis strictly at the root (drip irrigation, watering can without sprayer, furrows along the row).
• Water in the morning so that the leaves have time to dry by evening.
• In hot weather, you can water during the day (if the water is not cold), but also at the root.

6. Ignoring Sanitary Pruning

Mistake: not removing diseased, damaged, or misshapen ovaries, as well as faded flowers that will no longer set fruit.

Why it is bad: diseased and misshapen ovaries are a source of infection that can spread to healthy fruits and leaves. In addition, they consume nutrition that could have gone to forming quality fruits (Kotov and Adritskaya, 2016).

How to avoid:

• Regularly remove all misshapen, twisted, spotted, or rotting‑looking ovaries.
• Remove faded male flowers (they are no longer needed and begin to rot).
• Ensure that fruits do not come into contact with wet soil (place boards, mulch, or tie them up).

7. Planting on Cold, Waterlogged, or Acidic Soils

Mistake: planting zucchini in a low spot where water stagnates, or on acidic peat soils without liming, or too early when the soil has not yet warmed to 10–12 °C.

Why it is bad: zucchini does not tolerate water stagnation at the roots—they suffocate, and root rot and fusarium quickly kill the plant. On acidic soils (pH below 5.5), plants absorb phosphorus and calcium poorly, leaves turn yellow, fruits become smaller (Karataev and Sovetkina, 1984; Welbaum, 2015).

How to avoid:

• Choose sunny, well‑drained sites (not low spots, not heavy clay).
• If the soil is acidic, apply ash or lime (dolomite flour) in advance, in autumn.
• Do not rush with sowing—wait until the soil at a depth of 10 cm has warmed to 12 °C (in the middle belt, usually the end of May).
• When growing in open ground in cold regions, use hot beds (with biofuel) or covers.

Brief Summary of the Article

Caring for zucchini is a system of regular actions aimed at creating and maintaining optimal conditions for continuous growth and fruiting. The main takeaways:

1. Soil: loosen, mulch, control crust and weeds—this provides roots with air, water, and nutrition.

2. Plant: remove old leaves, thin crowded bushes, ensure ventilation—this extends plant life and reduces disease risk.

3. Fruiting: harvest every 2–3 days, do not allow over‑ripening—this stimulates the formation of new ovaries.

4. Microclimate: protect from heat and cold, water at the root, ensure air circulation.

5. Monitoring: weekly inspection helps to notice problems in time and adjust care.

6. Mistakes: avoid overcrowding, nitrogen over‑feeding, irregular harvesting, and watering over leaves.

Zucchini is a rewarding plant. Put in a little effort, and it will reward you with a harvest of tender, tasty fruits from mid‑summer to late autumn. Happy gardening!