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I planted 15 small (6" tall) blackberry plants from pots (9 Triple Crown Thornless and 6 Prime-Jim) in late April in southwestern Pennsylvania (USDA zone 5).

All of the plants look very healthy in color and shape, but after 6 weeks the Triple Crown hasn't moved more than an inch, and the Prime-Jim has grown at most 2 or 3 inches.

The native soil does have a lot of clay, but we added a bunch of compost and topsoil. There is definitely enough rainfall (maybe too much?). And while it's not full sun, it's not far from full sun, and there are healthy tall weeds growing nearby.

I read that the Triple Crown won't fruit during the first year, and growth should be moderate, but at this rate they don't look like they'll be much taller than a foot by the end of the season. What should my expectations for blackberry growth be during the first year?

I haven't done a pH test yet, it's a new property. But I did apply this blackberry fertilizer.

  • 2
    Heh. I shudder at the thought of planting blackberries. I yank them out by the handful! No idea what a cultivated blackberry should do, but wild blackberries easily shoot up to several feet in a year. What's your soil pH? They want it slightly acidic. – bstpierre Jun 9 '11 at 1:51
  • There's a technical term for what happened to your blackberries. It's called "dead". Note that even dead blackberries can take months before the leaves fall off even if you soak them in systemic weedkiller, so they are just fooling you into thinking they are still alive! If you do figure out what you did to kill them, you could make a fortune from marketing it - but they may have been dead when you bought them, of course. If they are not growing at least 6 feet a year in any soil conditions, there is something very wrong. Really aggressive "wild" species can grow 6 feet in a couple of weeks. – alephzero Aug 28 '17 at 19:58
  • The idea of actually buying special fertilizer for them seems completely bizarre to me (but them I'm in the UK not the USA). They will grow in anything - even a heap of brick rubble with no "soil" at all. – alephzero Aug 28 '17 at 20:01
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@keith - @bstpierre's pH test is a good suggestion. Since you already amended the soil and it seems to be raining enough. Sounds like you're getting enough sun.

One other thing worth looking at is your ratio of compost to the original clay soil. Clay tends to be very compact...which means that it doesn't drain well. It can prevent nutrients from getting to your roots as easily when you fertilize. Also, it can make it hard for the roots to expand. You need to make sure you allow enough buffer for the roots to grow below and around the original root ball. I usually try to allow a minimum of 6-8 inches; 12-16 would be better.

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Once they have become established in their new home, blackberry plants (particularly the varieties with thorns) usually grow quickly and aggressively - mine are so invasive that I have to be very vigilant to keep them under control! However, I see that your question dates back to 9 June, and you planted yours towards the end of April, which means that they had only had about six weeks in the ground when you posted, and that time would normally have been spent settling in. You were probably expecting too much of them.

By now, they should be growing vigorously, in preparation for fruiting next year (they don't normally fruit during their first year). Blackberries are not too fussy about soil quality, provided it is free-draining, and yours appear to be getting enough sunshine and water. However, if they have still not grown much, I would suggest, in addition to the sound advice already given:

  • adding plenty of well-rotted horse manure to the plot where they are planted; this will open up the pore structure of your clayey soil and improve drainage and aeration, making it easier for your plants' roots to spread and absorb nutrients. Keep the manure away from the stems, to prevent collar rot, and avoid using cattle manure, which is more suitable for light soils and would have the opposite effect: it would make your soil even heavier and less porous.

The following articles should prove useful:

Growing Berries

Growing Blackberries

I hope you enjoy a good crop next year.

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I think it depends a lot on your climate and soil. If you live somewhere temperate like near the coast in Washington where blackberries commonly grow wild, I'm guessing they'll grow like weeds right away. I could be wrong about them growing like weeds right away in those areas, but that's the impression I get.

In my garden, which has a more clay-type soil, lots of summer heat, lots of sun, and a semi-arid climate, blackberries are prone to looking stunted for the first year or two after the transplant, and then they take off and grow plenty of fruit thereafter. It seems like it takes them a while to get used to the heat, the semi-ardidity, and/or the clay-type soil—but, get used to it they do. They can be hard to get rid of once they're established.

I doubt your blackberries are dead, especially if they look healthy, although it is possible. Transplant success rates with blackberries aren't 100%, from what I've seen.

You might try looking for more heat tolerant varieties, which possibly might be less likely to be stunted in heat the first couple years. I've heard of a couple varieties that do particularly well in the heat.

I'm not sure what southwestern Pennsylvania is like with heat, but the clay in the soil might be the issue if the heat and drought aren't (sounds like drought isn't the issue). Like others, though, I do recommend a soil test. We haven't had ours tested, yet; so, it could just have pH issues or something. However, if you're patient, you can likely still grow blackberries in it without doing anything too special.

I can tell you that there does seem to be zinc deficiency in at least some of our soil, though. Zinc deficiency can stunt plants, as can other deficiencies.

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    Once you have one blackberry, you don't need to transplant them. Seeds that get moved to a new location in bird poo will germinate anywhere - and usually where you don't want blackberries. As for "soil deficiencies," I've had them growing (and producing runners several feet long in a single season) rooted in a quarter-inch-wide crack between a solid concrete driveway and the foundation of a brick wall. No soil at all, no direct rainfall to the roots, no nothin' - but they are still pretty hard to kill off! – alephzero Aug 29 '17 at 20:02
  • @alephzero I think it's quite a bit different in a desert or steppe climate in compact soil (e.g. clay). I'm not saying that's what the questioner has, but I've never seen a single blackberry seed sprout anywhere on our property from birds (or anywhere else in my region). Black raspberries are another story here (they readily reseed, it seems). I've seen foliar symptoms of nutritional deficiency on a blackberry before, too. So, whether or not it happened with your plants and the plant in a crack, it certainly can happen. I don't mean to undermine your experience, though; it's pretty cool. – Shule Aug 30 '17 at 8:40
  • @alephzero Have you had this experience with purchased blackberries or do you grow wild ones? I'm not sure that there are any wild ones here. Well, I might have seen some on a ravine by a creek once (I guess it's possible that they came from birds), but just once, and it was a very unexpected sight. Anyway, it's possible that domesticated ones may not behave the same, or be as hardy as wild ones (which are probably fully acclimated to your area). Plants with at least one or two non-cloned ancestors that were grown in similar conditions seem to reseed a lot easier in my experience. – Shule Aug 30 '17 at 9:00
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When we Bought an apartment in Dubai we just had a small space to grow Balcony. Though it takes two years after planting to produce berries, blackberry plants can live up to 15 years in your garden.I would like to share a small tip which my My Indoor Garderns team(Sijigreenhouse) advised me that to prolong the life of your blackberry plants, avoid spreading viruses by not planting them near raspberries, (Rubus idaeus) hardy in USDA zones 3 through 10.

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