I have two grapefruits that my dad started from grocery bought fruit ruffly 20 years ago. They're pretty big, recently, in the past few years I've been repotting them and pruning them.
Is there a chance that they could finally make fruit? What could I do to help? I haven't repotted this year yet but I will and they're going into slightly larger pots. These pots are pretty big, I don't know how many gallons though.
When should I prune? Should I prune the roots when I repot?
I just took one outside, it's moved into full sun, I have to lug the other one out too. They put on a lot of growth last year after being in the sun.
I also fed with some miracle growth, is there a better food or formula to use like a bloom inducer and superthrive?
It'd be really nice to get some fruit after 20 years!
How to get my grapefruit to fruit?
Hate to tell yu this but some seedling citrus never bloom or set fruit, don't know why but they just don't. All commercial citrus are grafted plants or cutting grown to retain the wanted characteristics. Had a friend that had a 30 year old seedling......she liked the foliage..but never bloomed. :-)
The other bit of bad news is that ungrafted and standard grapefruit trees can get over 30 ft tall, way too big for a pot. How big is your tree? I grow some dwarf citrus trees ( Grafted on to dwarfing rootstock.) in 24" pots, but mostly in 30" fiberglass pots. I like fiberglass because it doesn't get brittle the way plastic does.
Most citrus set flowers and bloom in late winter/early spring. My kumquats bloom later. Bees are the usual pollinators. Usually, home gardeners don't have to prune except to remove crossing branches, damaged ones, to remove suckers or branches that have outgrown the rest of the tree. Commercial growers prune to keep them at the same height to make harvesting easier. You will probably have to prune yours to keep it in bounds and to force more branch growth. If you do that now, maybe you can get a few flowers which would have to be hand pollinated, but don't expect any fruit indoors.
Citrus fertilizer contains 3 micronutrients that citrus need. You can continue to feed it Miracle Grow, but look for a foliar fertilizer that contains chelated iron, zind and manganese. You apply it in early spring.
I like your persistance for having kept those trees alive this long.
If it helps any, my mother-in-law has a grapefruit, grown from seed, that has been producing fruit for years, but then she lives in Houston. Citrus are usually grown along the Gulf Coast, the coast or inland valleys of California & Arizona and along the lower Atlantic Coast. You would have the best chance of getting fruit from a grafted Dwarf Improved Meyer Lemon or grafted kumquats, either Meiwa and Nagami. Of these last two the Meiwa is the most flavorful. Given plenty of sunlight indoors as well as moisture, they should flower for you indoors. If you hand pollinate you might get a fruit or two. If you can't provide the sunlight indoors, the most you can hope for, realistically, is to keep them healthy and alive until you can get them outdoors after all frost is over for the year.
Sorry, I couldn't give you better news!
poor some grapefruit juice on it see if it want help J/K
ely