This week on Ask Gardenerd, Paula asks, “Good morning. I have four tomato plants growing in seven gallon containers on my deck one of the plants has a few blossoms that have dried up. I am concerned there is a problem I should be aware of. All seem to be growing well and fill the containers both vertically and horizontally. Thanks for your help.”
Several other gardenerds have asked about tomato blossoms not fruiting, and we run across this problem here at Gardenerd HQ. So it’s definitely time to address this issue. Let’s take a look at the problem.
Frequent Feeding Makes a Difference
It’s important to remember that containers don’t allow plants to dive deep for nutrients buried deep in the soil, so you have to give them everything they will need for the duration of growing, flowering, and fruiting. That means feeding them more often than you would with tomatoes in the ground. Even if you used the best quality potting soil when planting, tomatoes still need a lil’ sumthin’ sumthin’ along the way. Add compost and worm castings when you fertilize to boost soil microbial activity.
Phosphorus and Potassium are responsible for fruiting, flowering, and overall vigor. It sounds like you’ve got enough Potassium, but are probably lacking phosphorus. We like sea bird guano as a good source of phosphorus. We use it in our home made fertilizer.
Advice from Our Favorite TomatoManiac!
We asked Scott Daigre from TomatoMania about this issue, and he said he was working on a post to answer the same question. Seems you’re not alone, Paula. Here’s what Scott had to say:
“Growing in containers is a terrific way to grow tomatoes. However, it also can be the most inconsistent space in which to grow. The plant wants consistency – there’s the challenge for home gardeners.”
Here are some of Scott’s check points to look at before feeding:
- How big is the pot? 15″ x 15″ or bigger? That’s optimal.
- Did you use all new high quality potting soil (plus amendments) when you planted?
- Where is the pot? On a hot concrete surface? Try to change that or limit reflected heat.
- What’s the pot made of? Black plastic or similar that will heat up intolerably? Wrap the pot with canvas or burlap – or anything. Keep the roots COOL.
- How much sun does it get? 6-8 hours of sun is full sun and all your plants need. Morning sun or searing late heat? Opt for the former. 12 hours of sun a day on a container planting could be considered torture!
- If all those items are dealt with or have been accomplished then you, the gardener, are the wild card.”
Scott suggests fertilizing containers “every ten to fourteen days.” We’ve even started feeding weekly here at Gardenerd HQ to curtail the issue quickly. Once we see improvement, we’ll back off.
Scott also suggests watering “as consistently as possible. Depending on the size of the pot, what the pot is made of and how much sun it’s exposed to you might be watering every day.”
We hope these tips help you achieve a higher fruit set with your container tomato plants, and finally end the issue of tomato blossoms not fruiting. Don’t give up, Paula! We’re all in this together.
This Post Has 22 Comments
I’ve spent this entire summer babying the tomato plants. Watering, feeding, calcium given, shaded when needed with umbrella. Evidently I’m doing everything wrong,,,,,,,we’re in 90 plus degrees for the most part, lots of triple digits as well,,,planted in resin plastic whatever the material is whisky barrels, sitting on slab concrete patio. I’ve watered gazillion gallons of water especially in the triple digit days. To be rewarded with one beef steak tomato that’s the size of a gold ball. Now my orange peppers are producing but stunted growth. Cucumbers produced but all of a sudden they stopped. Thinking I should stick with buying my fresh vegetables at the store.
Hi Bridget, in temperatures over 90 degrees tomato pollen becomes sterile and the blossoms drop instead of setting fruit. It’s not your fault. Consider starting your tomatoes earlier next year so that they have time to set fruit before the high temps arrive.
Try misting the blossoms as I read that a little bit of humidity helps fertilization. My peppers were dropping blossoms as well as baby peppers then I added a bit of bone meal n I got a survivor. Try adding a wee bit of phosphorus n watch for improvement.
It seems you blame it on being in containers, but I have 16 plants in the ground and had a soil test and fertilized according to that, plus added manure before planting and used tomato miracle grow and 10-10-10 fertilize every 14 days. I dont know how my tomatoes isnt burnt up with all ive put on them, but they’re heathly and look great but are 4 or 5 foot tall with only 2 tomatoes. I had problems last year also, just barely getting bloom sets. I think the problem lies elsewhere other than their in containers or your not watering correctly. Any ideas?
Jason, tomato fruit set is also effected by temperature. Temps over 90 degrees F will cause pollen to go sterile and flowers will just drop instead of setting fruit. So if you’re experiencing a lot of hot temperatures where you are, that can be a contributing factor.
A friend told me about “Tomato & Blossom Set” spray. It seems to be helping some, but still have some falling off.
Go flower to flower with a q-tip couple times a week. Ive been doing this for a few yrs, IT WORKS if you dontnhave a lot of bee population. You can also find this method on YouTube along with many other ideas/suggestions. Happy harvesting!!!!
The fix is actually pollination with an electric toothbrush. Look it up on YouTube. Professional greenhouses use this method because bigger heirloom tomatoes can’t really pollinate itself. Humidity also plays a roll, but try the electric toothbrush. That’s what fixed my tomato plants.
Lots of blooms no fruit. Growing in pot like always, this year ?? I’ll truu fertilizer. Thx
Yes, try adding fertilizer. First, test your soil for levels of Phosphorus and Potassium. Containers shed nutrients more quickly than in-ground plantings. Those 2 elements are responsible for fruiting and flowers.
Also, if temperatures are over 90 degrees the blossoms will drop instead of setting fruit. Might be a little early for those temps, but keep that in mind as summer comes on. Good luck!
You need a high “k” number that is potassium, which is for fruit. And bloom set is a hormone supplement that strengthens hybrid plants.
I’ve been having the same problem, tomatoes flowering but little or no fruits
I’m thinking of using cow manure is that good.
Manure is considered very “hot” meaning it can burn your tomatoes. So I suggest using compost and worm castings instead with a little seabird guano (Down To Earth sells a phosphorus-rich product). Once temperatures drop below 90 degrees tomatoes will start setting fruit again. So keep that in mind.
Let you know that tomatoes are fruit and vegetable because I’m growing some right now and starting to sprout it’s should take while I got more vegetables like summer squash and cucumber I water and feed them
All my roma tomatoes flowers are falling off I would have to say it’s due to temperatures in the low 90spast few weeks now it started to cool off and has begun to flower again hope this helps
That sounds about right, Adam. I hope the cooler temps bring successful fruiting.
I live in Oklahoma and a lot of people around here are having the same problem. I have planted in the ground. Virgin ground.
My vines are healthy, about 4 feet. I have a lot of blossoms then they drop off. I am so flustered.
Sorry to hear, Nina. If temperatures are running hotter than 90 degrees that could account for the blossom drop. Not much you can do about that. Pollen goes sterile at that point. Otherwise it’s usually a deficiency of phosphorus and potassium in soils that account for it. I hope these tips help turn things around.
All your advice is amazing. I had no idea so many things could affect the blossom drop on my tomato plants.
Best fertilizer for tomatoes in pots?
We like a number of organic fertilizers on the market. Dr. Earth, EB Stone, Fox Farm, G&B, Down To Earth. Just feed more often than you would in-ground plants, as nutrients wash out with watering.