It's a couple of months since I introduced you to the black tomato I'm trialling this year, so I've put aside my salad leaves this month to bring you a full report on how they're doing.
'Indigo Rose' hails from Oregon State University in the USA and has been available there for a couple of years. We had a spontaneous exchange of experiences on the coach on the last day of the Portland Fling, so I'm not alone in the observations I'm about to tell you about.
This tomato was bred as a healthier option by crossing cultivated tomatoes with wild species from Chile and the Galapagos Islands. It's higher in anthocyanin (hence the purple/black colour), which are naturally occurring antioxidants in plants which may help to protect our nervous system, plus they may have have anti-cancer, antidepressant and pain killing properties.
|Anthocyanins aren't confined to the fruit, they're in the leaves and stems too. This picture also shows the |
tendency of the leaves to curl slightly. Unlike other tomatoes this isn't usually a sign of a problem.
|Flowers and fruit - fairly large trusses of medium sized fruit are produced. You can also see |
the fruit's tendency to stay green underneath where they're not getting sufficient light.
However, I think this may have been too early as the tomato was almost tasteless. The university's website says the fruit take around 90 days to ripen (which is fairly slow) and I've found that leaving the tomatoes as long as possible before eating does give them a better flavour.
Part of the problem is knowing when the tomatoes are actually ripe as there aren't the usual visual clues. A completely black tomato doesn't necessarily mean it's ripe. I've found if the fruit also has a slight give where it joins the stem, then it's time to pick. You also need to eat them quickly at this point, or if they've gone the colour shown in the picture as they don't keep that well.
Some do go completely red (and will be ripe) like the usual tomato. This is probably due to the anthocyanins varying in colour with pH. In the lab they're green-yellow in alkaline, purple in neutral and pink in acidic conditions. I've also noticed the red or browny-red tomatoes are much juicier than their more fleshy, black cousins.
|NB the tomato size on this plate isn't representative - they're not cherry tomatoes.|
Most 'Indigo Rose' are 2-4 times the size of 'Sungold'
Inevitably some tomatoes do fall off before they're ripe. These take a long time to ripen compared to their pictured 'Sungold' relatives. Note that 'Indigo Rose' is an open pollinated variety, so it's possible to save their seed. The jury is still out on blight resistance; I haven't had blight yet on any of my tomatoes, but then we've had a pretty dry summer thus far.*
* = and I'm also trying blight prevention using an aspirin spray which James Wong mentioned earlier this year.
The stems are more brittle than the other tomatoes I'm growing this year (Sungold and Moneymaker). When the remains of Hurricane 'Bertha' swept through the garden a couple of weeks ago, all my tomato plants fell like ninepins and some of the 'Indigo Rose' stems snapped (the other varieties just bent over). I've put the stems in vase on the patio making the most unusual bouquet I've ever had and to give the tomatoes a chance to ripen.
My final verdict?
Early to flower, yet longer to ripen; sturdy yet brittle plants; attractive fruit, yet difficult to know when ripe, this is a tomato with good and bad points which scores strongly on novelty value.
So far as a salad tomato it's rather lacking in flavour, though it has been improving with age. Perhaps late season is when it comes into its own? However, its fleshier fruiting habit means I've had a tastier success with salsa and sauce making, so perhaps this is where this tomato's true forte lies.
I've also heard there are further developments in this breeding line which are an improvement in the flavour department. So watch this space!