My grapefruit tree won't flower, When I bought the tree from a nursery it had 3 grapefruits on it. When I brought it indoors due to the weather, part of it died, I pruned it back , it started to grow now it has beautiful leaves and strong stems but no flowers. I fertilized it, and still no flowers, it's about 2 years old. What can I do to make it flower? brownssn
Welcome to the forum. Exposure to several weeks of cool temperatures during winter will encourage development of flower buds. Do you have a sheltered location where the tree can be over-wintered? For example an attached, unheated balcony or garage where the temperature is moderated by heat leaking from the main structure. If temperatures there remain below 13C/55F the tree will go dormant. In that case the tree should be kept in the dark with irrigation kept to a bare minimum. What fertilizer are you using? More detail: Flowerbud Induction Overview and Advisory - UF/IFAS Extension: Solutions for Your Life
In the winter I keep my plants inside in the basement in a small greenhouse with grow lights. I use organic citrus-tone fertilizer for my plants. My lemon plant will flower during the winter months, indoors but not the grapefruit and the small fruit will fall off the lemon plant even after they are brought out side in the spring. Here is a photo of my green house.
Lemons are classified as everbearing, not so with grapefruit. Perhaps that accounts for the difference. Does the lemon bloom heavily or sparsely? In any case, cooler temperatures would likely increase the number of flower buds. I'm not familiar with the fertilizer you are using but one with an NPK ratio of 5-1-3 and which contains micronutrients is recommended for containerized citrus.
The lemon blooms sparsely. Is there a certain brand with that ratio or any fertilizer with that ration will do? The fertilizer that I use has the ration of 5-2-6 and the brand is made by Espoma
The one with that exact ratio that I know of is 25-5-15 High Performance-Jack's Professional - J. R. Peters Inc.. I wouldn't be too hung up on the ratio as long as it's close. Does your basement have cool temperatures? If so, perhaps you can grow the trees without the greenhouse, which would likely trap and retain heat from the lights.
Yes, in the winter my basement is cool and sometimes it's kinda of chilly. Before I got the greenhouse and the plants where just in the open basement all the leaves fell off. This time when they were in the greenhouse none of the leaves fell, the grapefruit plant grow so tall with no flowers, I had to cut in down some in order to get it out. Also when I brought them out for spring I didn't lose any leaves. I really don't know what I'm doing wrong.
I suggest you get a thermometer down there to see what you're working with. It would be best if you get one of those digital ones that record the maximum and minimum temperatures as well as the relative humidity. It shouldn't cost much these days. I mentioned earlier that citrus go dormant at temperatures below 13C/55F. A tree in that condition, exposed to bright light, will drop its leaves as it's roots are unable to provide the moisture necessary for photosynthesis. Perhaps that is what happened to you. (If indeed that is the case, you could then opt to keep your trees in the basement and in complete darkness until conditions are more favorable.) You may want to place the containers on some insulating material to get them off the cold floor, which appears to be tile. I think you've got something to work with; I'd rather have a cool room than a warm one - it's more natural for the tree. Knowing the conditions that are necessary to induce flower buds, it's just a matter of tweaking things until you get it just right.
Thank you, for all your suggestion and information. It never hurt to try something new. I will try your suggestions when I bring them in for the winter. Since the plants are outside now and looking healthy and the weather is in the 90's is there any way I could get them to maybe flower before they have to come in for the winter or will I just have to wait until next year.
I'm don't know the answer to that. The lemon could flower again since it's an everbearer. Perhaps there's a simpler explanation for the lack of flowers in the grapefruit. From the UF/IFAS link above, Do you think this might apply in your case? You would probably like more opinions unfortunately there's very little activity in this forum. Therefore you may want to post your question elsewhere. There are a number of knowledgeable enthusiasts in the citrus forum at Tropical Fruit Forum - International Tropical Fruit Growers - Index. You could make an inquiry there.
