onion seedlings have yellow tips and have stopped growing

Asked April 15, 2019, 10:23 PM EDT

I planted Red Wing and Patterson onion seeds indoors in Feb. using fresh seed from Pinetree Seeds. For the first time, I used mostly Burpee Coir seedling mixture, fresh bag. I may have also added some peat moss and some compost, but not much. The seeds germinated okay and grew okay for about a month or maybe less. I cut them back only once. The tips then turned yellow and the plants have stopped growing, completely. They are quite short, about 2-3 inches. They have been this way for months. I thought perhaps there was low nitrogen so gave them a very diluted dose of 7-7-7 liquid fertilizer. But no change. A few people online have had this same problem, but no answers were given, even with a university extension replying. (they suggested low nitrogen or over watering). The plants have been given pretty good sun, either via window or grow lights, depending on the weather. Somthing is not right and I'm afraid I'm going to lose my entire crop. (I rely on onions extensively). Am concerned that the plants have a disease. To the naked eye the roots and small bulbs look okay. There is just NO leaf growth. I also noticed that the lettuce I grew indoors in a pot, using similar soil was also quite pale, though it did grow. Am wondering if the coir is not a good medium, or if there were pathogens in the compost. I had no real dampening off problems. I've used Pine Tree onion seed before without problems. I suspect the soil is "off" in some way. Any suggestions are appreciated. thank you.

Stearns County Minnesota

3 Responses

Many people, including Minnesota master gardeners, have reported problems with the product you mentioned. Unfortunately, so far as we know, no one has determined what accounts for this.

This is what we learned from one affected Minnesota master gardener:

"Master gardeners all over Minnesota had difficulty with this product going back about three years. I had thought maybe it was product shipped to a certain area, but this was not the case. I was attracted to the product by the word organic and the fact that coir was used, a renewable resource. I doubt if coir was the problem as it is used in many other gardening products. I had no success in four communications with Burpee and only one response where I was asked where I purchased the product. In that response they stated that there is some variation depending upon the area."

According to most respondents, performance of the affected seedlings did not improve. They did not "grow out of it."

Although we can't recommend a remedy, you may be able to salvage your onion crop by purchasing seedlings still available from many sources. Unfortunately, this is a costly alternative to growing your own from seed.

Thank you for replying and confirming that the product is most likely the cause. I'm wondering if the coir simply has a toxic level of salt, but I don't know. I removed each tiny, stunted onion plant, rinsed off the soil and replanted in a different mix, but this may be a longshot.
I returned the product to Menards and explained my experience. I was the only person to return the product, they said, but they will ship it back to Burpee.
Am awaiting a response from Burpee. I'm shying away from coir and plan to go back to peat moss. I don't use very much of it. Thanks again.

Your attempt to remedy the problem must be tedious, but perhaps worth the effort if it makes a difference. Good luck.