I’m amazed by the number of questions I receive on how to grow less common fruits and vegetables, especially tropical and eastern herbs and spices.
Now unless you have a huge heated greenhouse some crops are going to be difficult. Indeed even if you could grow them some would not have a good flavour and this applies especially to those that need careful preparation after harvest. For example you might be able to grow a vanilla orchid, you might be able to get it to flower, even possibly pollinated but could you ferment the pods to just the right degree or would they go mouldy instead? Difficult. As with wine, it’s not just growing the grapes but the soil and climate and then the processing that make a top rate product.
Black and White Pepper are whole or naked fruits of a climbing vine that takes about three years of humid tropical heat to start cropping, fresh seed is not often available and the curing can be a little tricky. So despite it’s immense economic value pepper has seldom been grown away from it’s original area with any success. There are similar difficulties with nutmeg and mace (both on the same tree), allspice /aka pimento, cloves, and cinnamon. These are not only trees a tad large to fit under cover but get their exquisite flavour from their growing conditions. So although you might be able to grow these the quality would probably be much poorer than the cheapest commercial offering. Furthermore these are all somewhat difficult to find viable seed for, the items sold in commerce are either too old or have been treated so they will not germinate. Star Anise has allegedly long been boiled to protect the growers’ monopoly.
Many seeds such as in fresh Cardomom capsules and in Tamarind pods can be started but cardomoms, although herbaceous perennials, reach three or four metres high, and Tamarinds are huge trees -simply too tall. Still cardomoms are just within the range of possibility. Please don’t let my remarks stop you from trying anything; but some other spices are somewhat easier, in particular those that come from more compact growing plants.
Probably the most gratifying, and valuable is ginger. This is not difficult providing you give it a little bottom heat throughout it’s life as grown ‘cold’ it tends to be miserable. Get a fresh supermarket root early in the year- look for one with intact greenish rounded buds showing as these are often grated off to improve the shelf life. Ideally choose a many fingered root with a bud to each finger, detach these fingers and allow the cut end to dry for a day or so. Then pot them up in free draining moist gritty compost and keep somewhere really warm. The buds break and tall somewhat grass like shoots emerge. Liking it moist and warm; ginger does not like dry bright conditions and does better in amongst other plants, and as I said, with a little bottom heat. However given moist warmth and regular potting up, eventually to bucket size containers, it can grow really well and reaches about waist height. Sometimes flowers are formed but these never set. Keep the soil just moist never wet and feed regularly for the largest crop. If you harvest the root before the leaves wither in autumn it is succulent and it can be crystallised as stem ginger (not difficult but a somewhat tedious process). If left till the leaves wither then let the compost dry out, the stem bases will toughen and the lot becomes fresh root ginger which may keep for a few months. Root ginger does tend to either wither or rot though so is best used fairly promptly once evicted from the dried off compost or oven dried and ground to a powder.
Galangal and turmeric are similar spices to ginger and similar in habit and cultural needs -though turmeric has much broader more canna like leaves. As with ginger the seed is effectively unknown, sadly fresh viable roots of these are harder to source. The turmeric in particular has usually been scalded to stop shooting in storage. Once obtained just grow like ginger.
At the other end of the scale is Lemon-grass. I cannot believe any gardeners are still buying this as there’s no crop easier to grow. It’s a weed of both wet and dry land and not even particularly tender. Any piece from the supermarket will probably root and those with the shoot base still attached are the easiest. This can be in water but preferably in moist gritty compost. Once a piece has started rooting, grow on, feed and water and harvest shoots as you require. The plants can even go outdoors for the summer. Each time you cut a shoot for use detach it with a piece of the base which you can root and grow on separately. Be careful with the leaves as like pampas grass they are razor edged.
Although many now grow pak-choi for stir fries few grow Shungi-ku, the edible chrysanthemum that goes with it for an authentic flavour. This is also a good companion for this and other cabbages, the strongly flavoured leaves are added to stir fries as are the distinctive yellow and white petals. A very easy to grow annual, and handy for cut flowers.
True Limes are amongst the more demanding of the citrus family, tropical in cultivation and decidedly tender. However like other citrus, limes are not at all difficult and stay conveniently compact. Best bought as grafted plants as citrus are very slow to crop from seed (my Ortanique took twenty three years!). There are several lime impersonators and lime/lemon hybrids often substituted for the real lime in commerce (even unripe lemons have been sold as limes) so sowing seed is especially risky. They like to be outside in summer and cool, bright and frost free in winter. A well drained semi-ericaceous gritty compost, regular feeding in summer and rain water and they are content.
As easy to grow as citrus and not much more tender are Guavas, these produce wonderfully scented fruits. And they can also be grown for their dried foliage and pruned wood which when damped and burnt impart the perfect Caribean aroma to jerked and barbecued meats. The fresh fruits are sometimes sold and contain viable seed, these bushy shrubs are quick to grow under cover -and easy to control as you keep trimming them.
Also very similar in habit and cultural requirements to citrus and worth growing from seed (you are unlikely to find plants) is the Curry Leaf used to give a curry flavour. This is not the grey leaved border perennial Curry Plant Helichrysum angustifolium but a tropical woody perennial shrub /small tree. Unfortunately I found it possible to get substituted seed of the very similar Murraya exotica than of the curry leaf M. koenigii; be warned. Anyway as we’re after the leaves not the fruits then once true seed is got this should be easy to grow, M exotica thrives for me –it’s retained for it’s edible berries and perfumed jasmine like blooms.
However the common curry flavour is from Cumin seed. Now this is a doddle. You can find the seed in some catalogues and sometimes the kitchen sort is not past germinating. It does not like transplanting and is best under cover yet as it’s fairly dwarf it will fit under cloches. Sow in late spring early summer and harvest in autumn- simply collect the dried seed heads, sieve and clean. (To finish the seeds shake them mixed with dried peas then sieve these out after.)
Coriander is equally simple, the fresh leaf is used for salsa and other dishes but the dried seed is almost essential in countless more. Again this is a straightforward easy crop, though taller than cumin it’s not difficult in the open in a good summer, better under cover.
Although needed as much for European as Eastern cuisine Caraway, Mustard, Nigella (N. sativa) and Poppy (Papaver somniferum) seeds are other easy tasty seed crops, the caraway is a tad more trouble than the others, as it’s biennial so needs growing this year to crop next.
Sesame is not a difficult seed crop to grow though it struggles outdoors and needs to be under cover, but as it’s waist high and you need a great number of plants to give any amount of seed it’s barely worth the trouble.
Fenugreek is another marginal case, easy enough to grow outdoors when used as a summer green manure. However if it’s the seeds not the leaf (both are consumed) then it really needs to be under cover where it barely earns it’s keep.
Okra is likewise a poor return. Though not strictly a spice more a texturising agent employed for it’s gooiness, essential in gumbo and in many Indian dishes - in order to get enough pods at a time you need a large number of plants so must dedicate your entire greenhouse to them.
However there’s a close relative of Okra, also from the tropics, that you really should be growing. You only need a few plants as it’s the highly scented flowers of Sorrel or Roselle you’re after. This is an annual crop that needs sowing early in the year on heat and growing on, if you can get seed when catalogues have it. Hibiscus sabdariffa var. sabdariffa has foliage you can eat like spinach, seeds you can toast and eat, with dark red flowers of which the fresh or dried sepals give the most delicious clove, allspice and cinnamon flavour to teas, puddings, trifles and alcoholic beverages. Indeed this one really is a case of grow your Christmas.