GU7 vs GU8 vs GC Clones: Which Eucalyptus Clone for Your Site
GU = E. grandis × E. urophylla. GC = E. grandis × E. camaldulensis. Broadly: GU for good, well-watered sites; GC for drier or more marginal ground.
The number is a catalogue reference, not a quality grade. GU8 is not "better than" GU7 — it is a different selected individual that may suit different conditions. Anyone selling you a clone on the basis that the number is higher is not a clonal nursery.
What the Codes Mean
| Code | Cross | Bred for | Best fit in Uganda |
|---|---|---|---|
| GU (GU7, GU8…) | grandis × urophylla | Vigorous growth with broader site tolerance than pure grandis; generally better disease and pest tolerance | Lake Victoria crescent, central plateau, Bunyoro — good to moderate sites |
| GC (GC540, GC796…) | grandis × camaldulensis | Grandis growth with camaldulensis drought tolerance | Drier ridges, northern districts, marginal ground |
| The number | — | Identifies one specific selected individual, propagated vegetatively so every plant is a genetic copy | A reference, not a ranking |
Two clones of the same cross can behave very differently — in growth rate, in form, and particularly in gall wasp tolerance. That is why the specific clone matters more than the cross.
Matching a Clone to Your Site
The rule that matters
- A clone matched to its site outperforms seedling stock, sometimes substantially.
- A clone mismatched to its site can underperform ordinary seedlings. Clones are precision instruments and precision cuts both ways.
- Which means: assess the site first, then choose the clone. Choosing a clone because it is popular, or because the nursery has it in stock, inverts the decision.
- If your site has not been assessed, quality seedling stock is the better risk-adjusted buy. See clonal vs seedling.
What to ask a nursery, in this order:
- "Which clones do you have, and what are their trial results in this region?" Tolerance and growth data are regional. A clone that performed in another country's trials may not here.
- "What is this clone's gall wasp record locally?" A real clonal operation tracks this.
- "What rainfall and soil depth does it want?" If the answer is vague, so is the stock.
- Verify current recommendations with NARO / NaFORRI or your district forestry officer before a large order. Recommendations shift as pest populations change.
We inspect clonal nurseries on behalf of growers before large orders.
Four Questions That Expose Fake Clonal Stock
Mislabelled clonal material is a genuine problem in the East African market. You pay a premium specifically for genetic identity, and you do not find out for two or three years.
- "Where did your mother stock come from?" A legitimate clonal nursery names the source of its stock plants. An evasive answer is the answer.
- "Do you propagate here, or buy in?" Both can be fine. Buying in without knowing the upstream source is not.
- "Can I see the bed this batch came from?" True clonal stock is visibly even — same height, same leaf, same vigour. Marked variation in a bed labelled as one clone means it is not one clone.
- "What is your rooting percentage?" Operations that actually propagate know this number. Resellers do not.
Do Not Plant One Clone Across the Whole Block
A monoclonal planting shares a single vulnerability. If that clone turns out to be susceptible to a pest that arrives or intensifies, the entire block is exposed at once.
- On larger holdings, plant two or three clones in separate compartments.
- Or retain some seedling-grown material in the mix for genetic diversity.
- It costs almost nothing and spreads the risk meaningfully.
Full species context in the eucalyptus species and clone guide.
Frequently Asked Questions
What is GU7 eucalyptus?
GU7 is a specific clone of the Eucalyptus grandis × Eucalyptus urophylla hybrid. GU identifies the cross; 7 identifies the particular selected individual, propagated vegetatively so every plant is genetically identical.
The number is a catalogue reference, not a quality ranking.
Is GU8 better than GU7?
No — that is not what the numbers mean. They are different selections that may suit different sites, rainfall and pest pressure.
Anyone selling you a clone on the basis that the number is higher is not running a clonal operation.
What is the difference between GU and GC clones?
GU is grandis crossed with urophylla, bred for vigorous growth with broader site tolerance and generally better disease tolerance. GC is grandis crossed with camaldulensis, combining grandis growth with camaldulensis drought tolerance.
Broadly: GU for good, well-watered sites; GC for drier or more marginal ground.
Which clone is best for Uganda?
There is no single best clone, only a best match for your site. Assess soil depth, drainage and rainfall zone first, then choose.
Ask the nursery for local trial results and gall-wasp tolerance in your region, and verify current recommendations with NARO or your district forestry officer before a large order.
How do I know I am getting the clone I paid for?
Ask where the mother stock came from, whether they propagate on site or buy in, to see the bed the batch came from, and what their rooting percentage is. Genuine operations answer all four immediately.
True clonal stock is visibly uniform. Marked variation in a bed labelled as one clone means it is not one clone.
Should I plant only one clone?
Not across a large block. A monoclonal planting shares one vulnerability, and if that clone proves susceptible to a pest the whole block is exposed at once.
Plant two or three clones in separate compartments, or keep some seedling-grown material in the mix. It costs almost nothing.
Match the Clone to the Site, Not the Stock List
We assess the ground first, then tell you which clonal material suits it and which nursery can actually supply what it claims.
Over a decade establishing, measuring and managing eucalyptus, pine and indigenous plantations across Uganda. Based in Wakiso, Kampala. Reviewed and updated September 6, 2026.
