Pruning Berries

As I get more varieties of berries in my garden, it becomes harder to remember how each variety should be pruned, so I decided to document what I knew, add more detail, and ask others with expertise in this area for input and feedback. Here is the result.

When is the best time to prune berry bushes?

Traditionally berries were pruned in early winter after they had lost their leaves.  If you are new to pruning berries, that may still be the best time to prune them, because you can clearly see the structure of each bush.

However, the thinking now is that pruning-wounds heal better when the plant is not yet dormant. It is recommended that bushes are pruned after fruiting has finished, and before they lose their leaves and go dormant.

Pruning berries in late winter, when buds have begun to swell, is not recommended because you risk snapping off swelling buds.

How old is this branch?

Some people find pruning a scary business because you could be cutting the very branches that would have given you berries next season if you had not cut them away.

So let's look at a few simple ways of recognising how old a berry branch is, and then you will lose the fear of cutting away too much.

In most berry varieties young canes have a light brown colour. A good example is the side-branch in the photo below. 

A light-brown first year cane growing out of an older darker cane.

This side-branch comes out of an older darker branch. Older canes have a dark or silver colour.

Examine the bark of the six raspberry canes in the photo above. The three canes on the left are alive. The three on the right are dead.

How do you quickly ascertain whether a branch is alive when standing in front of it? Push and slightly bend the cane, left to right. If the cane snaps, it is dead, and can be cut off.

Pruning is not just cutting away dead branches, but the rules for pruning berries are not difficult.

General rules for pruning berries

• Open up the centre of the bush to air and sunlight by removing branches that grow inwards
• Open up the centre of the bush by pinching/rubbing off inward-facing buds.
• If two branches cross and touch, or are likely to touch when it is windy, cut away or divert one of them - they may damage each other and this may cause disease.
• Cut away low branches that touch the ground.
• Cut away branches that are clearly thinner and therefore weaker than other ones.
• Remove canes that break. They will be dead in most cases.
• Do not treat pruning wounds. Exposure to air is all the bush needs to heal itself.

If you have not pruned a bush for many years, do not prune it too radically in one pruning session. Take its size back over more than one season, so it does not suffer ‘pruning shock’.

Pruning tips specific to the most common berry varieties

If you follow the rules above you can't go far wrong with whatever berry variety you prune, but not all berry varieties produce fruit in exactly the same way, so here are some tips and hints that are specific to the most common berry varieties.

Blackberries

New branches come up straight out of the ground, or grow from buds at the base of older branches (‘basal buds’), or grow further along older branches as side shoots. These first year branches are lighter coloured and do not bear fruit. It is best to tie them up if there is a chance they will sprawl over the ground.

Fruit is produced on second year branches. At the end of that second season these branches are often recognizable by the spent flowerhead. Their colour has now become darker and many of them die.

Prune bushes so you have just 6 or 8 branches left.  These are preferably strong first season branches, but they can also be older branches with strong first season side shoots. Tie them to a trellis or wires and then shorten them to 2 – 2.5 metres long.

Some people first select the 6 or 8 branches they are going to keep, tie them together to one side of the wire or trellis, and then cut off the rest at the base.  The following year they then tie the next lot to the other side of the trellis or wire, so they grow in the opposite direction. That makes it easy to know which ones to cut.

Shorten side shoots on vigorous canes to about 4 buds.

The same pruning method is used for other Brambles such as the Boysenberry, Loganberry, Silvanberry and Youngberry.

Blackcurrants

New light-brown branches come up straight out of the ground, or grow from buds (experts call these ‘basal buds’) at the base of older branches , or grow further along older branches as smaller side shoots.

On Blackcurrants first year branches are the ones that bear fruit.

Second year and older branches are darker. Cut these down to a promising, ideally outward facing bud, or to just above ground level if there are no promising buds.

In a recent discussion about pruning blackcurrants on our group's Food Gardeners Tasmania Facebook page FGG member Margaret M. commented that she prunes away branches that have ripe blackcurrants on them right at the base. She prunes at the time of picking fruit. In fact, she picks fruit and prunes at the same time. 

This simple way of pruning blackcurrant bushes is justified if you read again the first two paragraphs of this section. If you follow this method you drastically revitalise your blackcurrant bush at the end of each season and avoid problems with Currant Borer Moths (see below), but you miss out on side shoots that will develop along older branches and produce fruit.

You may find that some Blackcurrant branches have black hollow centres (see photo below). The black centres are made by grubs of the Currant Borer Moth. 

black centres caused by Currant Borer Moth

If you inspect a branch with a black centre you will find that somewhere it has a hole (see photo below). This is where the grub of the Currant Borer Moth emerged.  It dug and ate its way through the centre of this branch, probably both up and down from the hole.

 a hole made by a Currant Borer Moth grub

The branch will be very much weakened, especially above the hole, and not produce any fruit. Cut away a branch like this completely, or cut it off just above a promising bud further down. If after cutting, the centre of the remaining branch is still black or hollow, remove more of the branch. You may have to cut the whole branch off just above ground level.

Blackcurrant bushes need constant renewal to ensure heavy crops, so don’t be afraid to give them a rigorous pruning.

a Blackcurrant bush before pruning

the same bush after pruning

Blueberries

Blueberries belong to the same plant family as azaleas and rhododendrons. Blueberry varieties for sale in Australia are nothing like the small bushes I picked berries from in forested areas in the Netherlands when I was a child.  Some of the varieties for sale in Australia do not lose their leaves in winter.

Blueberries fruit on one year old wood, in other words on branches that formed last year.

The best time to prune them is after harvesting has finished, but pruning in early winter is fine too.

Blueberries have a shallow, spreading root system and suckers can appear above ground some distance away. Remove these to prevent the bush becoming too spread out.

Next consider taking out older canes to encourage new ones.  Take them out, either at ground level, or by cutting back to a vigorous-looking young side-shoot.

If a young cane looks weak, either take it out entirely or cut it back to a more vigorous side branch.

If a young cane rapidly grows skywards into a long branch, prune it back to about half its length. This will encourage the development of fruit-producing side-branches.

Boysenberries

The Boysenberry is a member of the Bramble family.  Pruning is the same as for the Blackberry, a prominent member of this family, so follow the notes outlined there.

Gooseberries

Gooseberries can be pruned just like Blackcurrants, so see Blackcurrants.  Pay some special attention to the shape of the bush and picking fruit will become a lot less painful.

Over time many Gooseberry bushes become 'heavily-armed' and not easy to pick without hurting yourself.  

Picking can be made easier by cutting off at ground level all but one single main trunk, keeping the centre open and allowing the bush to spread widely via side branches off that main trunk.  If you do this for a few years, the bush will have a bowl shape.  Most Gooseberries will hang down freely and will be much easier to pick.

Jostaberries

Jostaberries are a cross between a Blackcurrent and a Gooseberry. Pruning is the same as for Blackcurrants, so follow the notes outlined there.

a Jostaberry before pruning

the same bush after pruning

Loganberries

The Loganberry is a member of the Bramble family.  Pruning is the same as for the Blackberry, a prominent member of this family, so follow the notes outlined there.

Raspberries

There are two types of Raspberries and how you prune them depends on what type you have. Ask yourself: do my raspberries have their main crop in early summer, with some more later in the season (summer-fruiting varieties) or do they have their main crop in Autumn (Autumn-fruiting varieties)?

• Summer-fruiting varieties fruit on second year branches. Just snip off tips of unruly branches. Canes that have produced fruit in their second year are darker and brittle and will snap when shaken. Cut these canes off at the base.

• Autumn-fruiting varieties fruit on first year branches. At the end of each season simply cut all canes at the base. Next spring new canes will appear. Let them grow for two months, and then cut their tips off to promote more fruiting laterals.

Red Currants

Red Currants are different from many other berries in that they fruit for some years on permanent spurs (short side branches) coming off sturdy shoots that grow out of the main stem at their base.

With this in mind work in the first two years of the life of the bush towards a framework of between 8 and 12 well spaced, sturdy shoots off its main stem at the base. Do this by removing spindly branches that come up from the base.

It is recommended that you shorten the main leads in early summer so they don't become any longer than 45 centimetres. This is because the wood at the point where the main lead joins the base is not overly strong.  Windy conditions may see a main lead ripped off the main stem at the base.

After fruiting, prune Red Currants according to the general pruning rules outlined above. When, after some years, fruiting on a main leader stops happening, remove the whole branch, so new growth is encouraged. 

Silvanberries

The Silvanberry is a member of the Bramble family.  Pruning is the same as for the Blackberry, a prominent member of this family, so follow the notes outlined there.

Strawberries

Strawberries are not a woody berry, but they do need pruning.

Pruning strawberries is done in mid winter. You can be pretty ruthless here, except that you should not cut away anything from the crown, that is the middle bit. Cut away most leaves at the base of their stalk, leaving only one or two healthy looking ones on each bush. In spring new leaves will emerge from the crown.

a strawberry bush before pruning

the same bush after pruning

Strawberry bushes do not last as long as many other berries. In most cases bushes will be productive for two years (that is including the year you got them as little plants – ‘runners’). If they are still vigorous at the end of the second year, you can keep them for a third year.

By the end of that third season, at the latest, you need to pull the whole bush out and replace it by a new runner, if you want to get the most out of your strawberry patch.

White currants

White Currants are a group of cultivars of the Red Currant. White Currants should be pruned the same way as Red Currants.

Youngberries

The Youngberry is a member of the Bramble family.  Pruning is the same as for the Blackberry, a prominent member of this family, so follow the notes outlined there.

Getting the best out of your pruning tools

You need a pair of secateurs for thin branches, a lopper for thicker ones, and a pruning saw to cut older really thick wood.

It is good practice to dip secateurs in bleach for a few seconds after each bush, or clean them with a piece of cloth you dip in bleach, so a disease that is affecting one bush is not transferred to another one.

Before doing any pruning, check whether your secateurs and lopper are ready for the job. Try them on a few branches. You need to be able to make clean cuts with blades that snap back into a closed position. If your secateurs do this, you can skip the rest of this section on secateurs.

Your secateurs may be dirty or even rusty. If this is the case, take them apart (this can be done easily with good quality secateurs), wash the parts in warm soapy water, and then remove remaining dirt and oil with fine sandpaper or an abrasive pad.

When all parts are dry, sharpen its blade with a sharpening stone. This is not complicated. Applying some pressure rub the stone along the edge of the blade, at slight angle so the edge becomes slightly more pronounced. You are succeeding if silver-coloured steel becomes visible at the very edge of the blade (see photo below). Touch the edge lightly with your finger to see whether the blade has some sharpness.  It does not have to be raiser-sharp to make a clean cut.

When finished, oil the part of each blade that will touch the other blade with vegetable oil or household oil. The spring may also need oiling. Now put it all together again, then open and close the secateurs a number of times to spread the oil. The secateurs should now close by themselves. That little movement of the secateurs closing by themselves saves so much time and irritation while pruning, that it is really worth the time you have given it.

Wipe off any excess oil with a piece of cloth.

Many thanks Max K, for contributing your expertise and checking this blog post for accuracy.

Thanks also to Margaret W, for your valuable knowledge on insects and other useful feedback.

If you would like to know more about growing berries or growing fruit in general, you can do no better than get the excellent The Complete Book of Fruit Growing in Australia by Louis Glowinski (Lothian Books).