Hello, squash growers. If you received any of the Cucurbita squash mixes from Going to Seed, we’ll be sending you a series of emails that offer information and guidance for growing these crops. While we hope that the suggestions we offer are helpful, it would be great if those of you who do things differently or have overcome a problem can share your methods (and climate/soil conditions) here because it may help someone in a similar environment. Questions about growing squash can also be posted here.
Thanks for being a part of this community. Looking forward to learning from all of you.
I have successfully grown summer squash from starts for years, but have often struggled with direct seeding winter squash in my cool spring soil. I know one of the reasons for adaptation gardening is often to push the boundaries of what species are capable of, but for more experienced squash growers, what signs or conditions are you looking for in your garden that indicate it’s time to plant your squash? Soil temperature? Weather patterns? Growth patterns of perennials or earlier season crops? Or do you just plant out lots of seed at a specific time and then thin as needed?
Personally it’s the other way around, similarly my direct sown seem to out perfom the ones that my neighbors plant (as I don’t transplant that much anymore). Over here advantage is that there is quite clear difference as to when summer starts and possible set packs usually don’t last long (even if our summer might be just set pack after other compared to some other places). Direct seeded usually tolerate those the best as well. Could be too wet in your case more than just the temperature. If you have really long transition period between spring and summer it might be quite hard to adapt cucurbits to take advantage of the whole period. Squash generally needs ground to be +15C/59F (15-20cm depth) so which month you have daily averages close to that might be when it’s likely they will survive. Over here june is just slightly under that. As a rule weather forecast tells me enough last week of may that I know if I can sow then or if I wait a week or so more. Before that changes are that the weather will still change one more time, even if it’s been good weather for them grow. Probably there you have also some date before which it’s most years just too early, but when you can also see forecast long enough to judge if it’s gonna stay good enough to get to summer weather. I remember long time ago when I was a beginner trying to plant squash way too early and year after year failing. There are some barriers that are just too far and it’s just matter of trying out what might be realistic pushing the limits in your climate.
Like Jesse, I check the weather forecast for consistently warm temperatures to decide the best time to direct sow squash seeds. I have put seeds out earlier, assuming that they will germinate when it’s best for them, and potentially find ones that germinate in cooler soil. But I’ll also put out seeds later when the soil is warmer so there’s less chance of the seedling stalling its growth due to a cold spell. In this case, I think this selects for plants that can reach maturity in a shorter time.
Thank you for reminding me that not everyone can order seeds from Going to Seed. Below is the first email (Apologies to those who are already well past their last frost date. We’ll try to do better next year.) I would very much appreciate comments and criticisms to improve the information presented. Thank you!
I would say 10-15 days is the sweet spot for transplants. Bigger very fast loose the advantage of longer time because of transplant shock, but also with 10-15 days there is some room for delays. Especially for beginners it’s easy to be unaware of year to year variance of their climate and get in trouble once that year comes.
This ofcourse depends on where you are as to how consistently warm weather you can wait. I would define more in term of when historically it’s unlikely that plants will die whether it’s frosts or several weeks of rain with highs in 10-15C/50-59F range. Can’t avoid cold periods here, but can avoid mostly frosts and have the cold spels be under a week. With the exception of moschata, squashes seem quite fine with cool dryish weather in short periods. In my own moschata I have also have had clearly improved early cold tolerance, but also have had staple varieties that at same time didn’t want to germinate and perished in first turn to colder. So if conditions are reasonable (average monthly around 15C/59F) it’s probable that there are some that will survive that in any squash species.
If you’re sowing seeds outdoors, wait until the soil is consistently above 18°C (65°F). Lower tempeatures slow and decrease germination.
Lowest acceptable air night temperature for seedlings is 10°C (50°F). Below this, squash seedlings may suffer from stunted growth, leaf yellowing, and increased vulnerability to disease.
Critical minimum air temperature (danger zone) is 5°C (41°F) and below. Even short exposure can kill seedlings or severely damage tissue, especially if they are recently transplanted or not hardened off, or planted in a windy zone.
I typically direct seed, Arizona zone 10a and sandy soil, and deeply 4-6 inches deep for seeding. I did build the soil with horse manure and composted wood chips a few years back, always organic, never chemicals. I also released red wiggler earthworms into the soil.
Even with direct seeding early, like the last week of February to the end of March, sprouts diddnt appear until the soil warmed up, it still feels cool to the touch but not uncomfortable. I succession plant until the end of April, every week for 5 weeks. The plants that sprout when its cool do stall, grow super slow and take off when temps get to be in the 80’s and higher. There is always basil and dill, some mix of herbs planted as companion plants to be enjoyed in teas or cooking as the season grows out.
I have also started seed in plug trays and planted out as transplants, also succession planted. Once the seedlings get true leaves, I start transplanting. But I only transplant 10-15 seedlings each week, until all are planted over a 5 week period. The seedlings are protected inside a greenhouse from a late random frost. They all eventually catch up to each other and produce like crazy. Ive had volunteers pop up to from a rotten squash left on the ground from the previous year, dried up from summer heat, but somehow the seeds remain viable whilst sitting on the ground.
For me, I have to plant something in both the ground and the trays. The seedlings from the trays can also be dotted in wherever another plant has failed. Something always grows, I watch them carefully to try to determine what is working.
They do better in direct sunlight for the entire day. At the end of the season I chop and drop old plants and let them compost into the growing soil.
Just keep planting. Plant as much as you can, the GTS seed and another 2 packets of different squash seeds. Even if they are the same variety, start with something in your soil.
The soil I planted in with earthworms does the best. The soil with compost also does really well even though I stoped adding compost. But starting that way allowed something to start growing, let me save seed, and grow again for another season.
I wouldn’t pay attention to just sort of “snap shot” of temperature but instead look at the whole picture. How hig does it get during day, how long the nights are, is it raining, has there been cool temperatures for long that would lower the ground temperature and thus go even lower with another cold night etc. Couple years ago we had a late, very light frost that damaged leaves of different species, including squash, but with no significant amount of casulties. Lows generally in june are under 10C and often under 5C. They definetely grow slower, than if it was a warm june, but I would say it’s more about temperatures generally being lower than just night lows. It can easily be 5C at night and over 25C during day or it’s 10C during night and 15C during day. The latter is way worse.
Thanks for all the detailed responses. This is getting at the heart of the matter. In May, we often have daytime highs around 15C, but can also have days where it’s much warmer, up to ~25C. Nighttime lows are consistently between 9-13 C, only occasionally colder and never frosting. Our coldest nights tend to be when skies are clear and days are warm, but overcast/cloudy nights (most common) lead to long cool damp and foggy mornings with less sun exposure. A confusing time for squash. I will try to take the whole picture into account.
I looked at the weather statistics for your area and it seems like spring/early summer months are just as warm, just one month earlier. Lower latitude and proximity to sea makes some differences, but I would think it’s rainfall that is the most significant difference when it comes to growing squash. Over here winter and spring are driest periods. Colder winter does conserve more of the moisture, but I would still think it can dry up more here by the time it’s time to sow squash. If it rains similarly to your avarages in may it’s really a problem. No-dig might help in that, but if you get a lot more than your average combined with coolish weather it’s definetely bad for squash. If I here can sow late may/early june, in your place probably 1 month earlier as averages would suggest might be a little early. Some years yes, but mid may or later might be more realistic. Squash seem to be fairly though when it comes to temperature, but not so much with excess moisture.
With enough seeds it’s possible to take even high casualties. Like last year for me with melons and watermelons. June was a little cool for them, but still I had some 1% that survived (excluding survivors that were too weak to ever fruit) which was enough from thousands of seeds. Since you still have fairly long season for squash, you could do several sowings to have change of extreme selection, but at the same time make sure that some have a good change.
Looks like we are comparing apples to oranges and delving into details, while the original document is meant to give a universal advice that fits the majority of the new growers. That is why I have given the most universal (IMHO) information on temperatures, rather than discussing my local conditions.
For me, killing night frost that comes first week of June makes average daily temperatures not very useful recently in the beginning of the season.
If I were to go by these numbers, I’d never sow squash. At no point in my season do I reach and maintain these temps reliably. Maybe for one day or two.
The ideal is for me to plant my squash around mid-April, right after our average last frost date. Sometimes I’m a bit of a, well, um, procrastinator, and don’t get them in till later . . . sometimes much later! Last year, I only got some of the moschatas in in early August, which meant they had only two months to try to mature a fruit before the first frost in mid-October. Two of them just barely managed it! Boy, did I save those seeds.
Understood, but you are on the edge of squash growing range. I have assumed that people who will be using those instructions are in majority closer to the middle. Anyway, it was just a suggestion.
That’s why I would use averages as they are the most universal you can get. What you use as an example probably reflects what the average temperatures are when you usually have those low temperatures. Other places average might be same, but lows never get there or other way around. Long term average of 15C/59F without danger of frost (although it seems like 0.x C frost is survivable) seems the most universal you can get. It’s not perfect and my intution is that the futher south (long nights), cloudier and wetter climate you are, the more that should be (maybe 16-18C/61-65F) and inversely lower is enough the futher north you go and the drier it gets. Daily averages also have the advantage that it doesn’t make people too careful about temperatures that obviously aren’t even deadly, but rather look at the whole picture. It’s easy to make assumptions that are maybe only half correct. Like over here people tend to blame failures to cold summer whether it actually is cold summer or, like recently, even fairly hot in our standards.
I have lots of my own seeds, so I just plant whenever the weather allows. If it turns cold and they don’t sprout or if they do sprout and then get frosted, I just get out some more seeds and replant. I have had volunteer acorn squash and zucchini sprout and later survive a light frost, but ones I’ve planted early never have.
Last year, I only got some of the moschatas in in early August, which meant they had only two months to try to mature a fruit before the first frost in mid-October. Two of them just barely managed it! Boy, did I save those seeds. 