SJCJ
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squash seedlings turning yellow

I have had squash, zucchini, and cantaloupe seedlings growing for about 4 - 6 weeks in 3 inch net cups. The bottom leaves are turning yellow / brown. The plants look a bit yellowish rather than bright green. They are bottom watered about every other day sometimes daily when needed.. I am using 5000 K lights for 16 hours per day. The soil is fertilized. Plants are continuing to grow and producing flowers. I need suggestions as to how to solve this.

I will be planting them outside in about 2 - 3 weeks. Should I remove the blossoms since they will still be inside for a while yet?

imafan26
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Re: squash seedlings turning yellow

Is the soil constantly damp or do you let the soil dry out a little bit before watering. It sounds like they are getting too much water or staying constantly wet.
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applestar
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Re: squash seedlings turning yellow

I'm thinking they are getting too big. 3" is way too small for flowering cucurbits. It's best to plant them out just when their roots are touching but not yet circling the sides of the container for minimum root disturbance. So the trick is to figure out what is the best timing to start them inside.

You may want to start backup seeds now if you still have as much as 3 weeks to go. I could see the ones you have already started filling 2 qt to 1 gallon containers in that time if you want try uppotting, but it will be difficult to manipulate and handle them once they start vining.

I haven't started mine yet but plan on getting them started by this weekend. I pre-germinate then plant in recycled 1 pt to 18 oz containers and plant them out with 3-4 true leaves.
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imafan26
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Re: squash seedlings turning yellow

You may be right Apple, I just reread the thread and he said the plants continue to grow and flower. If the seedlings are flowering they are probably already stunted.
Happy gardening in Hawaii. Gardens are where people grow.

SJCJ
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Re: squash seedlings turning yellow

I let the soil dry before watering again. The squash are flowering but not the cantaloupe or zucchini so I wonder if the size is an issue for them. Squash plants are only 4 inches tall. Is it still likely they are too large for the pots?

How would I determine if they are overwatered? I look at appearance of soil and if it looks dry and feels dry to touch about 1 inch down I water. Correct?

Are the 5K bulbs ok to use? I searched around and they seemed to be in the recommended spectrum.

Thanks for answering and the welcome! I'm really looking forward to learning so much from you all and having a great garden this year!

imafan26
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Re: squash seedlings turning yellow

Usually seedlings are kept in their starter pots until the true leaves appear. After that they need to be potted up or transplanted out to the garden. If their growth gets checked they will be stunted turn yellow and flower when they are still very small. Sometimes they perk up transplanted to the garden but they usually do not reach their full potential.

These are approximate planting dates for different crops. You can put in a specific location if you like.

https://www.almanac.com/gardening/planti ... iladelphia
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SJCJ
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Location: Pennsylvania USA zone 6B

Re: squash seedlings turning yellow

Thanks Green Thumb. Are there any guidelines to determine pot size for seedlings? I think you are correct about my problem but I'm unsure how large a pot different plants require.

Also, would it be worth a shot to see if existing plants do ok outside or if better to start fresh? You mentioned they may not be at their full potential and I assume you mean they may not produce well. Are there any guidelines to determine potential veggie production?

imafan26
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Re: squash seedlings turning yellow

Pretty much anything that causes set back in vegetables weakens them they need to keep growing throughout their lives. Once they start flowering, they don't do much more growing.
Usually I pot up seedlings when they have their first set of true leaves into 4 inch pots. They will stay in 4 inch pots maybe 3 more weeks before they are transplanted into their permanent pots or locations. The size of the pot depends on the plant. Peppers go into one gallons for a year then up to 5 gallon pots. Large plants eggplant, tomatoes, sugar baby watermelons go into 18 gallon tubs. Squash goes into 18 gallon tubs or the ground, they require a lot of space for their leaves to spread out about 3 ft in diameter.

Green thumb is a designation, I am Imafan26
Happy gardening in Hawaii. Gardens are where people grow.

SJCJ
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Re: squash seedlings turning yellow

I just wanted to follow up with some info. I discovered. I added some Miracle Grow fertilizer to my seedlings 2 tsp. per gallon of water and they are now thriving. I was reluctant to try this since the soil was fertilized and a name brand soil so I did not think this could be the issue . Be ware that some veggie potting mixes may require additional nutrients.

imafan26
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Re: squash seedlings turning yellow

Thanks for coming back with an update.

Seeds don't need any fertilizer in the starter mix. In fact if there is too much nitrogen in the starter, the seeds may fail to germinate. The seeds contain all the nutrients the plants need to get by the first couple of weeks after germination.

I do add osmocote to my starter mix. It is slow release so even it does not put out a lot of nitrogen at one time and if I am slow in potting up, it buys me a little more time, being potbound becomes more of an issue then.

If you do not have a starter fertilizer you need to pot up to a mix with fertilizer or supplement after a couple of weeks and the true leaves come in.

To keep the plant from stunting, it is best to pot up or transplant out before they become pot bound, which will also turn them yellow and the leaves will be small.
Happy gardening in Hawaii. Gardens are where people grow.

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