A bowl chipped into solid rock is a bathtub with no drain. Every hole needs a channel cut out of its low side. That single cut matters more than how deep you dig.
Sections
Mark the row
Nine plants, 4.5 ft apart, 36 ft end to end. Which species goes on which end, and why the slope decides it.
Step 2Dig and plant
How deep, how wide, how much rock to chip, and what to backfill with. Wide and shallow beats deep and narrow.
Step 3Water
One drip line for the whole job. Where the drippers go, and the run times for the rest of this season.
Step 4Mulch
Wood chips, how deep, how much to order, and why nothing else gets planted underneath for three years.
Step 5The raspberry patch
Two rows with a walking path between. Trellis first, and the two root barriers that do different jobs.
ReferenceWhat kills them
Seven mistakes, most of which look reasonable at the time. Worth one read before you start.
1 · Mark the row
All nine go in one straight line running across the hill rather than up and down it.
The ground also falls slightly along that line, about 2 degrees, which works out to roughly 15 in of drop from the left end to the right end. That is enough to matter.
- Nine plants,
4.5 ftapart, making the row36 ftlong end to end. - Do not try to level it. Chipping 15 inches off the high end of solid rock buys you nothing that the planting order below already handles for free.
- Keep the whole row well clear of the septic drainfield.
Why that order
Water travels sideways along the top of the rock toward the low end, so that end stays wettest all season.
- Gooseberries high. They are the fussiest of the three about wet roots. Being on an end also keeps you from reaching past their thorns to pick everything else.
- Honeyberries low. They came from boggy ground and will not mind the damp. They also have to sit next to each other or they will not make fruit at all.
- Currants in the middle, which suits them either way.
2 · Dig and plant
These bushes keep almost all their roots in the top foot and a half of soil, and they spread sideways rather than down.
So you want wide and shallow, never deep and narrow. A deep narrow pocket chipped into rock is the worst possible shape.
The hole
- Aim for
18 inof soil between the rock and the surface.12 inis the least you can get away with. - You only need that full depth in a circle about
2 to 3 ftacross. Past that,8 to 12 inof soil spread out to roughly4 ftis plenty, and it can sit right on top of the rock with no chipping at all. - Chip about
8 indown into the rock and stop. Make up the rest of the depth by mounding soil above ground level. Every inch you mound is an inch you do not have to chip. - Cut a channel out of each rock bowl so water can leave. Aim it at the lowest corner, angled a little toward the right end of the row, not straight downhill.
- Backfill with about half bought topsoil and half the native dirt and rock fines you dug out. Straight bagged topsoil against rock settles and traps water right where the roots are.
Setting the plant
- Slide it out of the pot. The clump of roots and dirt is only about
6 inacross, so it does not need much room on day one. The depth is for three years from now. - Set it so the top of that clump sits level with the finished soil surface, not buried below it.
- If the roots are wound in tight circles from the pot, tease the outer ones loose with your fingers so they grow outward instead of continuing to circle.
- Backfill, press it down firmly by hand, and soak it once with a hose to settle out air pockets.
3 · Water
Short and frequent, never long and deep. A long soak just runs off sideways along the rock and is wasted.
Run a black poly tube the length of the row, sitting on the soil about a foot above the plants on the uphill side. The little red drippers punch into it.
Setting it up
- At the faucet you need a filter and a pressure reducer, both of which screw on.
150 meshfilter,25 psireducer. Skipping these is how drip systems die. 2 drippersper plant, not three. Yours put out 2 gallons an hour each, which is already more than this thin soil can take in.- Put them
8 inout from the stem, one on each side, roughly12 inapart from each other. Both slightly on the uphill side so water travels down through the roots. - Do not bunch them together. One saturated spot runs off sideways along the rock and only wets half the plant.
- Tube goes under the mulch, directly on the soil. Not buried, not on top.
- Drain the whole thing before the first hard freeze.
Everything runs off one line and one timer. No second zone, no extra valve. Total draw is 54 GPH once the raspberries are on it, against a limit of about 200 GPH for half inch tubing, so you have plenty of room.
Schedule
| When | How often | Each time |
|---|---|---|
| Rest of August | Every other day, daily in a heat wave | 8 min, wait an hour, 8 min again |
| September | Twice a week | Same |
| After leaves drop | One deep soak before the ground freezes, then drain the lines | 30 min straight |
Splitting each watering into two short runs an hour apart is what lets it soak in instead of sheeting off the rock.
Next spring, move the drippers out to about 15 inches from each stem and add the third one.
4 · Mulch
Wood chips from a tree service, the rough kind with leaves and twigs mixed in.
They lock together so they stay put on a slope, and as they break down they build the soil layer you are short on.
- Spread a thin layer of compost first, then
3 to 4 inof chips on top. The chips hold the compost from washing downhill. - Cover a continuous band about
5 ftwide down the whole row, not circles around each plant. You need roughly2.5 cu ydtotal. - Keep the chips
3 inback from every stem so the base of the plant stays dry. - Chips go on the finished surface only. Never in the bottom of the hole, never mixed into the soil.
- Leave the grass growing above and around the band. It is the best thing you have holding that slope.
5 · The raspberry patch
Two short rows stacked one above the other, below the berry row and off to the right.
The soil there is deeper with less rock, which is good news for drainage and bad news for containment. Runners travel farther and faster in loose soil.
- Set the trellis posts before you plant the golden row. Driving posts through an established root system later is far worse than doing it into open ground, and the trellis is the only thing that makes 4 foot spacing work.
- Keep both rows pruned to about
15 inwide on the wire. That leaves a33 inpath you can walk. Let them sprawl to 3 feet and the path closes to a foot and you are shoving through thorns. - Mulch the path with
4 inof chips and top it up yearly, since a walked path packs down. - Keep the path at ground level. Do not dig it out. A path cut below grade on a slope stops being a path and becomes a ditch that drains both rows into it.
The two root barriers
Raspberries spread by sending runners underground and popping up somewhere new. You need two barriers, and they are not doing the same job.
- Down the middle of the path,
18 indeep. This keeps the reds out of the golds. Reds spread harder, and once they take that row over you cannot tell the two apart until they fruit. Walking the path handles anything coming up in the path, but does nothing about a runner travelling underneath it. - Between the raspberries and the berry row, full depth. Raspberry canes coming up underneath a thorny gooseberry are miserable to dig out. This one runs up and down the slope, alongside the way water moves, so it blocks nothing.
- Wherever you hit rock, stop the barrier
3 to 4 inshort of it. Runners stay in the top 6 to 12 inches so you still catch nearly all of them, and water can pass underneath instead of ponding behind a sealed wall.
Water and pruning
- Snake one tube up one row and back along the other. No tee, no fittings.
5 dripperson the 6 ft red row,4on the 4 ft golden row, spaced every18 inalong the row rather than clustered at plants. They fill in as a solid hedge, so there are no individual plants to water. - Same timer, same schedule as the bushes. Short and frequent is safe here because the soil drains. The reverse is not true, so set the timer by the bushes on rock and let the raspberries ride along.
What kills them
Most of these look perfectly reasonable at the time you do them.
| Mistake | Why it kills |
|---|---|
| A sealed rock bowl | No drainage channel means the roots sit in standing water until they rot. |
| Gravel or chips in the bottom of the hole | A coarse layer under finer soil holds water above it instead of letting it drain. It makes the bathtub worse, not better. |
| A barrier sealed down to bedrock across the slope | Same dam, different material. Leave a gap at the bottom wherever the soil is shallow. |
| A continuous ridge of soil across the row | Dams the runoff coming down the hill and backs it up against all nine plants. Let the downhill edge taper out flat. |
| Raspberries where water collects | Root rot from wet feet kills more raspberries than every other cause combined. Mound them rather than digging them in. |
| Mulch piled against the stems | Voles nest there under the snow and chew the bark off all the way around, which kills the whole bush. |
| Landscape fabric | These roots want to grow up into the mulch layer, and fabric stops that. |