Many gardeners have experienced the disappointment of harvesting tiny squash from plants they’ve spent months growing and caring for. Luckily, there are ways to ensure that your plants produce larger squash.
Squash doesn’t reach their full potential size when grown in compacted, slow-draining, nutrient-poor soil and when they don’t receive adequate amounts of heat, sunlight, water, and nutrients. The size of squash can also be limited by fungal disease and soft-bodied insect pests.
Knowing why your squash is disappointingly small is the first step to growing larger squash next time around. Let us look in more detail at the reasons that prevent squash from growing as big as they could potentially grow.
Why Is Your Squash So Small?
Squash is a gourd vegetable from a genus of herbaceous vines called Cucurbita. The five most commonly grown species of Cucurbita come from South and Central America. Most squash plants have a sprawling growth habit, though several modern bush varieties are also available.
Squash is typically divided into two categories: winter squash and summer squash.
Summer squash is harvested in the middle of the summer growing season when the fruits are young, and their skin, flesh, and seeds are still tender and edible. Commonly-grown types of summer squash include:
• zucchini
• patty-pan
• crookneck
Winter squash is harvested in late summer or early autumn when the fruits have fully matured, and their skin and seeds have become hardened and largely inedible.
Some common types of winter squash include varieties such as:
• butternut
• buttercup
• Hubbard squash
| Type of squash plant | Harvest time | Average size (length) of squash fruit |
| Summer squash | 7 to 8 weeks from planting outside (early to mid-summer) | zucchini = 4 – 7 inchespatty pan = 2 -5 inchescrookneck = 5-10 inches |
| Winter squash | 3 to 4 months after planting (late summer to early autumn | butternut = 8 -12 inchesbuttercup =4 – 8 inchesHubbard = 25 -30 inches |
Squash plants are relatively easy to grow, but unfavorable growing conditions and incorrect methods can result in a large squash plant producing small fruit (or none whatsoever).
Aside from early harvesting, the several main reasons why squash doesn’t grow to its full potential size include:
• cold temperatures
• nutrient-poor soil or lack of fertilization
• compacted, slow-draining soil
• unbalanced soil pH level
• insufficient soil moisture level
• inadequate exposure to direct sunlight
• pest and disease pressure
To produce large squash, the plants need warm temperatures and fertile, fast-draining soil. They also need a minimum of six to eight hours of direct sunlight, and they need regular hydration to maintain adequate moisture in the soil.
Taking measures to prevent or mitigate damage from pests and disease is also vital for growing large squash. Squash plants struggle to produce large fruit when attacked by pests like snails, slugs, and caterpillars and by fungal diseases like powdery mildew, downy mildew, and blossom-end-rot (which prevents fruits from forming at all).
This is all well and good, but success depends on having a more detailed, in-depth understanding of the factors that result in small or non-existent squash. To help you on your way, here are seven major reasons that prevent squash plants from producing large fruit.
Reason #1: Planting Squash When It’s Too Cold
When growing large squash, it is tempting to plant squash out in the garden as soon as spring appears. However, squash plants need warmer temperatures to grow well – ideally 18 degrees Celsius (64 degrees Fahrenheit) and above. Their growth slows considerably below this temperature, and squash plants are easily damaged or killed by frost.
While it can be beneficial to start squash plants indoors early in the spring, especially in areas with short growing seasons, the plants shouldn’t be transplanted outside until the chance of frost has passed.
Even in areas with longer growing seasons that do not experience frost, it is not advisable to plant squash plants outside until temperatures are consistently at 18 degrees Celsius (64 degrees Fahrenheit) or above.
Reason #2: Poor Soil Conditions
Squash won’t grow to their full potential size if the soil conditions aren’t favorable. Soil structure, nutritional content, as well as moisture, and pH levels are key factors that determine squash size.
Heavy Soil Structure
Dense or ‘heavy’ clay soils and compacted soils tend to result in unhappy squash plants that produce small fruit. The dense structure of these soils means they are slow-draining and easily water-logged.
While squash plants need relatively high amounts of water, they don’t grow well or produce large fruit if their roots are saturated with water for extended periods.
Instead, squash plants prefer loose, airy soils that drain quickly.
Soils with high amounts of organic matter help to ensure a favorable soil structure while slowing the loss of moisture during drier periods.
Nutrient-Poor Soil
Squash plants grow large and fast, so they need soil that is relatively rich in nutrients. Squash plants produce small fruit when grown in soil that lacks adequate nutrition.
While fertilizers can be applied to compensate for nutrient-poor soil, enriching the soil before transplanting the squash plants is more effective and efficient.
Adding compost to increase the percentage of organic matter in the soil can provide the necessary nutrition.
Unbalanced Soil PH
When soil pH levels are either too high or too low, squash plants will be unlikely to produce large fruit. Squash plants grow best in a pH range between 6 and 7.
They are particularly sensitive to acidic soil, so a pH of 6 or below can significantly reduce their ability to produce large fruit. This is partly because squash plants will struggle to take up phosphorous, magnesium, and manganese, which are all important for fruit development.
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Reason #3: Incorrect Application Of Fertilizer
As noted above, squash plants have relatively high nutrient requirements. They won’t produce large fruit if they don’t receive adequate amounts of nitrogen during vegetative growth.
During fruiting, squash plants will produce small fruit if they don’t receive enough phosphorous, potassium, and minor nutrients like calcium, magnesium, manganese, and sulfur.
Recommended fertilizer applications vary depending on the nutrient profile of your soil. The following table gives a general idea of the major or ‘macro’ nutrients that squash plants need to produce large fruit.
| Nutrients | Application rate (in ounces per square foot) |
| Nitrogen | 5 to 9 |
| Phosphorous | 4 to 7.5 |
| Potassium | 0 to 150 |
The easiest, most effective way to give your squash plants the nutrients they need to yield large fruits is to incorporate organic matter into your soil. Top-dressing with compost is the best way to do this.
The table below gives one a sense of how good organic matter in the soil meets the nutrient requirements of squash plants. Put simply, more organic matter in the soil means that less fertilizer is required to produce larger squash.
| Percentage of soil organic matter | Nitrogen (pounds per acre) | Phosphorous (pounds per acre) | Potassium (pounds per acre) |
| less than 2% | 100 | 50 | 110 |
| 2% to 4% | 80 | – | – |
| 5% to 10% | 60 | – | – |
| more than 10% | 40 | – | – |
When fertilizer is used, it should contain nutrients in ratios appropriate for the specific stage of plant growth.
Excessive amounts of nitrogen when the plants enter the fruiting stage will encourage the growth of large green foliage, but it will also result in small, under-develop squash. Applying lower amounts of nitrogen relative to phosphorous and potassium is advised during fruiting.
Reason #4: Incorrect Watering Practices
While squash plants are heat-loving summer crops, they won’t produce large fruit if they do not receive enough water throughout the growing season.
Squash plants prefer the soil to be relatively moist. They can tolerate drier soil conditions for brief periods, but they won’t fruit well if the soil is excessively moist or water-logged.
Growing large squash, therefore, requires diligent watering. It is important to ensure that the plants have consistent access to adequate moisture in the soil while avoiding over-watering.
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Over-head watering is another incorrect practice that can be as problematic as giving the plants too little or too much water. Watering squash plants from above makes the foliage and fruit wet, dramatically increasing the risk of fungal disease (see Reason #5 below).
To grow large squash successfully, it is thus best to avoid wetting the foliage. Water should be applied directly into the soil without splashing the leaves, stems, or fruit. Drip irrigation is highly effective for this task.
Adding mulch around your squash plants can help with even water retention as well as keeping soil from splashing on the plants.
Reason #5: Insect Pests
Soft-bodied insect pests can cause significant damage to squash plants, reducing their ability to grow properly and produce full-sized fruit. The greatest harm is caused when pests attack young squash plants early in the season. Some pests cause physical damage to the plants, while others act as vectors for harmful plant viruses.
Insect pests that can cause problems for squash plants include:
• snails
• slugs
• aphids
• whitefly
• wireworms
If squash plants aren’t checked regularly for pests, infestations can decimate the crop in days. Performing regular pest inspection is important for identifying pest pressure early enough to intervene and prevent damage to the plants.
If larger crawling pests are found on plants or in the growing area, they can be removed by hand. Smaller crawling insects like aphids can be removed from the plants by spraying them with water.
While removing insects by hand is effective for pest control, it can be time-consuming. Using hand-removal in combination with insect traps can be an easier way to control pests. Deploying insect traps that target flying insects can be particularly useful because these pests can’t be effectively removed or controlled by hand.
Reason #6: Fungal Diseases
Fungal diseases can also cause squash plants to yield fruit that is not as big as it should be. Squash plants are prone to a range of fungal diseases that affect the roots, stems, leaves, and fruit.
Pathogenic fungi tend to attack squash plants when there is excessive moisture in the air, on plant surfaces, or in the soil.
Some common fungal diseases that attack squash plants and prevent them from developing large fruit are as follows:
• black mold
• fusarium
• root rot
As noted earlier, squash plants should be watered carefully because the likelihood of fungal disease is significantly increased when wetting the plant foliage or applying excessive amounts of water to the soil.
Powdery mildew is especially common on squash plants and can be treated with organic methods.
Reason #7: Too Many Squash Blossoms
Squash plants grow small fruit when there are too many blossoms. Plants have a fixed amount of resources to allocate to flower and fruit development, so if too many blossoms are allowed to form, each squash will have less water and nutrition to grow.
Fewer blossoms usually equate to larger squash because the plants can allocate more resources to each fruit. To ensure that your squash reaches its full potential size, removing excess blossoms before they start transforming into fruit is recommended.
The ideal number of squash blossoms per plant depends on the variety of squash and the individual plant’s size in question.
In most cases, larger squash varieties should have a low number of blossoms than smaller varieties. The typical number of blossoms per plant for common squash varieties is as follows:
| Squash variety | Blossoms per plant for growing large fruit |
| pumpkin | 1 to 2 |
| butternut | 2 to 5 |
| acorn | 2 to 5 |
| zucchini | 5 to 15 |
| patty-pan | 15 to 30 |
Conclusion
You should now have a better understanding of seven possible reasons why your squash is so small. Taking proactive measures to avoid as many of these problems as possible will greatly increase your chances of avoiding the disappointment of growing squash that is not as big as you’d hoped.
While you may not be able to avoid all the causes that lead to a squash producing small fruit, you will certainly be better equipped to avoid a good many of these seven causes.
References
https://www.almanac.com/plant/squash-and-zucchini
https://datcp.wi.gov/Documents/mk_fc_81web.pdf
https://escholarship.org/content/qt1cg4k6v2/qt1cg4k6v2.pdf
https://ucanr.edu/sites/nm/files/76628.pdf
