Growing squash from seed is one of the most rewarding garden tasks out there. Whether you’re growing prolific summer squash or massive winter squash, you’re sure to see results. Squash seedlings are easy to start but can be somewhat delicate. The best way to take care of them well is to understand their early stages so that you can reap a successful harvest.
Starting squash from seeds is an easy and rewarding way to grow your own fresh produce. Squash vines produce abundant yields of tasty fruits that can be eaten fresh, cooked canned frozen or stored over winter. With some planning and preparation, you can grow a productive squash patch right in your own backyard garden. This detailed guide covers everything a beginner needs to know about sowing, growing and caring for squash started from seed.
When to Plant Squash Seeds
The timing of planting squash seeds depends on whether you live in a warm or cool climate and your chosen planting method
If Starting Indoors
In cooler regions with a short growing season, start seeds indoors 3-4 weeks prior to your area’s last expected spring frost date. This gives seedlings a head start on growth so they will be ready to transplant outdoors once the soil has warmed up sufficiently. To determine your indoor planting date, check your local long-range weather forecast for frost dates and count backwards from the expected last frost.
For example, if your season’s final frost is projected for May 15th, start seeds around April 15th-22nd. Choose containers like cell packs, peat pots or trays. Provide strong light from a sunny window or grow lights. Maintain warm temperatures around 70°F.
If Direct Sowing Outdoors
In warm climates with long summers seeds can be sown directly in the garden 2-3 weeks after the last spring frost once soil temperatures reach at least 65°F. Delaying protects tender seedlings from cold damage. Check soil temperature at planting depth using a thermometer before sowing.
Using the example above with a May 15th frost, optimal sowing outdoors would be around May 29th-June 5th. Monitor weather and soil temps daily as planting time nears.
Selecting Squash Varieties
Summer squash and winter squash come in diverse shapes, flavors and colors. Consider available space, intended use and personal preference when choosing varieties to grow.
Popular Summer Squash Types
- Zucchini – Prolific yields, great for slicing, baking, grilling.
- Yellow Crookneck – Sweet, tender fruits on compact bushy vines.
- Patty Pan – Cute scalloped UFO-shaped fruits, best harvested young.
- Straightneck – Smooth, slim fruits excellent for sautéing and steaming.
Recommended Winter Squash Varieties
- Acorn – Small round fruits with sweet orange flesh perfect for stuffing.
- Butternut – Iconic pear-shaped winter squash, ideal for soups, baking and puréeing.
- Spaghetti – Oblong yellow fruits with tasty noodle-like strands when cooked.
- Kabocha – Stocky green squash with dense, nutty sweet flesh.
- Pumpkins – Large, round orange fruits perfect for fall decorating and baking.
How to Start Squash Seeds Indoors
While direct sowing is simpler, starting seeds indoors provides warmer conditions and a head start on the season. Here’s a step-by-step guide:
Supplies Needed
- Seed starting mix
- Containers like cells packs, pots or trays
- Watering can, mister bottle or spray bottle
- Domes or mini greenhouse (optional)
- Grow lights (optional)
Steps
- Fill chosen containers with moistened seed starting mix, leaving 1 inch headspace.
- Sow 2-3 seeds per cell or pot at the recommended planting depth, usually 1⁄2-1 inch.
- Gently water until the soil is evenly moist but not saturated.
- Optional: Cover with plastic domes to retain moisture.
- Place in a warm (65-75°F) spot with 14-16 hours of daily light.
- Keep soil consistently moist until sprouting in 5-10 days.
- Once sprouted, remove domes if using. Provide supplemental lighting if needed.
- Harden off seedlings for 7-10 days before transplanting into the garden after all danger of frost.
How to Direct Sow Squash Outdoors
For those desiring a simpler approach, seeds can be sown directly in warm garden soil. Follow these steps for success:
Supplies Needed
- Squash seeds
- Row cover or cloche (optional)
Steps
- Prepare soil by mixing in compost and fertilizer if needed. Smooth and rake beds.
- Sow seeds 1-2 inches deep in groups of 4-6 seeds (hills) spaced 3-4 feet apart down rows 4-6 feet apart.
- Cover lightly with soil, gently firming and watering. Consider using row covers for extra frost and pest protection.
- Once sprouted, thin to 2-3 plants per hill.
- Water weekly, applying 1-2 inches. Use mulch to retain moisture.
- Fertilize with a balanced product once fruits begin forming.
Caring for Squash Seedlings
Proper growing conditions and attentive care are vital for nurturing healthy, vigorous seedlings and productive vines.
Indoors
- Provide 14-16 hours of bright light and temperatures of 65-75°F daily.
- Water when the top inch of soil dries out. Avoid overhead watering.
- Fertilize weekly with diluted liquid fertilizer starting at 2 weeks old.
- Harden off for 7-10 days before transplanting outside.
Outdoors
- Thin overcrowded patches to improve air circulation.
- Water new seedlings daily until established. Soak soil 6-8 inches deep.
- Side dress with compost or fertilizer when vines begin spreading.
- Use row covers or cloches to boost warmth and growth.
- Weed regularly to prevent competition for water and nutrients.
Transplanting Squash Starts
When moving indoor-started squash seedlings to the garden, focus on preventing shock and providing ideal growing conditions immediately.
Tips for Success
- Harden off seedlings for 7-10 days first.
- Wait until outdoor soil reaches 65°F and air temps are mild (60-75°F).
- Space plants 18-36 inches apart down rows spaced 4-6 feet apart.
- Dig holes matching root ball depth. Carefully remove from pots.
- Backfill holes gently but firmly to eliminate air pockets.
- Water transplants immediately with starter fertilizer solution.
- Provide shade for 1-2 days while plants establish.
- Use row covers if desired to boost warmth and growth.
- Mulch once settled to conserve moisture and reduce weeds.
Troubleshooting Common Problems
Squash can be prone to a few issues in those first critical weeks. Here’s how to troubleshoot common challenges:
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Seeds fail to sprout – Likely caused by cool soil, planting too deep, poor seed contact or inadequate moisture. Resow when soils have warmed.
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Weak, yellowed seedlings – Insufficient light, irregular watering, or improper temperatures leads to stunted growth. Improve conditions quickly.
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Damping off or rotting – Fungal disease induced by excessive moisture and poor air flow. Allow soil to dry between waterings and space plants properly.
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Leaf chewing – Insect pests like cucumber beetles, slugs, snails. Use row covers until larger and hand pick pests.
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Wilting transplants – Disturbed roots, inadequate watering, or too much sun/heat. Carefully replant, water deeply, provide shade.
With the right timing and care, starting squash from seed can yield an abundant harvest. Monitor those first few weeks closely and you’ll reap prolific vines and bountiful fruits throughout the entire growing season.
The Anatomy of Squash Seedlings
Like most vegetable seedlings, squashes are dicots, meaning they have two cotyledons. Cotyledons are the “seed leafs.” They are what exists inside the seed and pop out first upon germination. These leaves are photosynthetic and help get the plant started until it’s strong enough to produce its first “true leaves.”
The seed is the embryonic stage of the plant life cycle. Squash seeds, like most seeds, contain three main parts: the embryo, the endosperm, and the seed coat. The embryo is the fertilized part of the seed, or the part that actually becomes a plant. The endosperm is made up of starches, oils, and proteins and is what feeds the embryo once it sprouts, but before it’s able to take up nutrients from the environment. The seed coat is the protective outer layer of the seed.
When a squash seed comes into contact with moisture, the seed will start to take up water through the seed coat. It will then swell, which breaks the seed coat open from the inside. The embryo, made up of a small shoot and small root, will emerge root first, anchoring the seed to the soil. Then the shoot will emerge and you’ll see the cotyledons.
Common Challenges and Solutions
There are a number of issues you can run into with squash seedlings, but they’re easy enough to avoid with understanding and a few preventative measures.
Damping off is a fungal issue that can be exacerbated by certain environmental factors. The fungus can cause seeds to decay without germination or affect seedlings. Typically the stem at the soil surface will turn brown and the seedling will fall over, killing it.
Once damping off begins, there is no turning it around, however there are some steps you can take to mitigate the effects of this fungus or stop it entirely! Damping off is exacerbated by cold, wet conditions. This means that overwatering coupled with a lack of a heat mat can make things worse. Airflow can also affect damping off. We recommend keeping a fan running in the room where your seedlings are growing. Keeping air moving around the room can help to mitigate all fungal issues!
“Legginess,” as we call it, refers to a seedling with an oddly long stem. Often leggy seedlings will be leaning one way as if reaching for something, and this something is most often a light source. If you notice your seedlings getting leggy, you’ll want to give them more light by either moving your existing grow lights closer to the plants or giving them more time outside in the sun (while watching for cold weather, of course).
There are any number of nutrient deficiencies that could be affecting your squash seedlings. If you are growing your seedlings in a high quality, nutrient-dense seedling planting mix, you should not run into any issues with this. If you’re growing them in low quality potting soil or something similar, you will likely find that your seedlings may “fail to thrive.” They may get to a certain height and stop growing entirely. The best way to tackle this is to ensure that you’re planting in a high quality mix — something that is dense in nutrients and micronutrients, but not too high in nitrogen, which can burn seedlings. You can find high quality soil mixes at your local nurseries, hardware stores, or even make one yourself!
Too much water fills in all the air pockets in the soil, which robs the roots of oxygen that’s needed for proper root growth and development. You may see molding on the surface of the soil or on the plants themselves. This can also result in a failure to thrive and limit development significantly. We recommend adequately moistening your soil at planting time — to the point that when you squeeze a ball of it in your hand, the soil holds its shape, but doesn’t squeeze out water — and then misting the surface of your soil twice a day or watering from below. Remember, overwatering can also exacerbate damping off, so keep an eye on that soil temperature and airflow as well.
Unsurprisingly, underwatering can also cause problems. Insufficient watering can cause the leaves to turn yellow and eventually drop. You’ll see the leaves wilting as well.
As discussed earlier, damping off is an incredibly common seedlings issue, but there are other things to watch out for as your squash seedlings are developing! Pest infestations can cause major problems before you’re able to harvest.
Aphids can be a common problem for seedlings, particularly if you put your homegrown seedlings near ones you purchased from a nursery without quarantining them first. If aphids infect your seedlings, gently clean them off with a damp cloth. Make sure you’re getting as many as you can or perhaps check and wipe them daily. If your infestation is really severe, you can always apply neem oil which should take care of the problem.
Squash bugs are likely to be found on your seedlings in the garden if you’ve direct seeded or after you’ve transplanted. This is particularly true if you’re succession planting and growing squash later in the season. While squash bugs aren’t actually all that harmful to an established plant, they can wreak havoc on young squash seedlings. Try to catch them early, killing the rust colored eggs. If the population has matured you can also remove them by hand and drop them in a bucket of soapy water.
Squash vine borers can be a problem for squash plants of all ages but are especially harmful if they attack your plants early. They do exactly what the name indicates. They bore into the stem of the plant, usually close to soil level, and feed through the center of the stems, hollowing them out and blocking the flow of water from the roots to the rest of the plant. This can quickly decimate an entire crop. Prevention is the best tool! The moths that lay the eggs at the stems of your plant are attracted to yellow. Some growers use yellow sticky traps and others use yellow bowls filled with soap and water to trap them, which can stop them from laying their eggs. Further, a physical barrier will help as well. Consider using row cover, before your seedlings are flowering, so that eggs cannot be laid. And if your squash seedlings do get attacked, there are still steps you can take. Monitor your plants closely for signs of wilting or boring. If you notice issues, take a clean sharp knife and cut a slit into the affected stem. Slice carefully until you find the borers and remove or kill them. Once you’ve done this, pack moist soil around the cut area and keep it watered well. More roots may sprout at the sight and you might be able to save the affected plant!
Like other cucurbits, squash seedlings can be prone to transplant shock. This doesn’t mean it’s explicitly not recommended or can’t be done, but it’s something to consider when deciding what seeds to start indoors and what to direct seed.
How to Grow Squash | Basic Tips for Incredible Success
FAQ
How do you germinate squash seeds quickly?
Direct sow or transplant in late spring once the soil is warm. For transplants, start seeds indoors during the first two weeks of May. Optimal soil temperature: 25-35°C (77-95°F). Seeds should germinate in 7-14 days.
How to start squash seeds indoors?
Do you have to soak squash seeds before planting?
You can soak your squash seeds before planting to encourage faster germination. Put them in clean water and let them sit for a few hours before planting. However, this is not required as long as the growing medium is moist and warm, the squash seeds should germinate well.
Can you grow squash from seeds?
Growing squash from seeds is one of the easiest and most rewarding gardening projects for beginners. Squash vines produce an abundance of tasty fruit that can be enjoyed fresh, cooked or preserved. With just a little planning, you can have a productive squash patch that provides food all season long.
How do you start squash seeds indoors?
Before you begin, gather all the materials you’ll need for starting squash seeds indoors. This includes seed starting trays or pots, seed starting mix, and either grow lights or a sunny window for proper lighting. Next, fill your trays or pots with the seed starting mix. Follow the recommended depth on the seed packet for sowing the squash seeds.
How to germinate squash seeds?
When germinating squash seeds, it is crucial to prepare the planting medium properly. One key aspect is choosing the right soil. Opt for a well-draining mix to prevent waterlogged roots and promote healthy seed growth. To further enhance the soil’s quality, it’s recommended to incorporate organic matter.
How long does it take to grow a squash?
This is an incredibly easy vegetable to grow, but because it can take 120 days to mature it is best to start your seeds indoors if you have a short gardening season. This type of squash takes up a large space in your garden and is ready to be harvested when the skin turns hard. This type of squash also produces the most vegetable per plant.
When should I start growing squash from seed?
When learning how to grow squash from seed you should always start indoors. This will help minimize the risk of weather, pests, and disease. When learning how to grow squash from seed you will want to start your seeds inside approximately 8 weeks before you plan on moving your squash into your garden or moving your planter outside.
How long does it take for squash to germinate?
The indoor temperature should be 66°F to 85°F (18-29°C) until germination. Sow seed ½ to 1 inch (1.3-2.5 cm) deep. Seeds germinate in 4 to 10 days at 85°F (29°C) or warmer. Transplant squash into the garden after the soil has warmed to at least 70°F (21°C). Space plants in the garden 12 to 18 inches (30-45 cm) apart in all directions.