How Much Neem Khali and Sarso Khali Does a Pot Need?

A 10 to 12 inch pot takes 100 g of neem khali or sarso khali, mixed into the topsoil and watered in, repeated every 30 to 45 days. At garden-pack prices in India today, roughly ₹222 to ₹254 per kg, that is about ₹22 to ₹25 per pot per feed.

Neem khali is neem seed cake. Sarso khali is mustard oil cake. They are the two oil cakes Indian terrace gardeners use, and they cannot be swapped for each other. Dose, interval and price differ enough that using one in place of the other wastes both.

Dose, method and repeat schedule for each container size

One hundred grams, or about one cup, per 10 to 12 inch pot dug into the first 3 to 5 cm of soil. Smaller pots need 25 to 30 g. Ground beds need about 25 g per square metre. Fresh potting mix takes 10 to 20 g per kilogram of mix.

A 12 inch pot holds roughly 8 to 10 kg of mix, so 100 g lands near 10 to 12 g per kg, the low end of the 10 to 40 g per kg range used in published soil-amendment trials. The bed figure follows ICAR extension guidance putting neem cake at 250 kg per hectare before sowing, which is 25 g per square metre.

How often should you re-apply?

Re-apply every 30 to 45 days through the growing season. Oil cakes work only as fast as the soil microbes breaking them down, which is why their effect fades over that same window.

One soil study found neem cake's biological activity diminished by 15 days after amendment and had gone by 30. A trial on neem materials as nitrification inhibitors found the effect lasted about 40 days, which is why its authors recommended neem seed material for short-duration crops such as vegetables.

For a fast crop like methi or palak, one dose at sowing is enough. For tomato, chilli, brinjal or roses, plan three to five feeds a season.

Mix it in or sprinkle on top?

Incorporate it into the mix. Both cakes need soil contact and moisture before microbes can do anything with them, and a dry layer on the surface mostly just smells. Fork the powder into the top 3 to 5 cm, keep it 5 cm clear of the stem, then water well.

A liquid version is available. Soak 1 part powder in 15 parts water for 24 hours, then use it to water your plants. It works faster and smells less, but treat it as a top-up, since most of the slow-release value stays in the solids.

What does neem khali cost per kg in India?

Expect roughly ₹200 to ₹260 per kg in retail garden packs, with larger packs cheaper per kilogram. SatRas prices its 900 g pack of neem khali at ₹229, down from ₹300, and its 1.8 kg pack at ₹399, down from ₹599. That is ₹254 and ₹222 per kg. Sarso khali is priced the same.

In pot economics, a 100 g feed costs ₹22 to ₹25. One 900 g pack covers nine feeds of a 10 to 12 inch pot, while a 1.8 kg pack covers eighteen. Ten pots on a 45 day cycle use about 1 kg per round, roughly ₹222 at the larger pack rate, or near ₹150 a month.

Bulk 50 kg sacks are cheaper per kilogram but are milled for field use and arrive coarser.

SatRas mills its neem khali from the whole dried neem seed, the nimboli, rather than kernel residue alone. Its sarso khali is cold-pressed mustard oil cake powder.

Neem khali or sarso khali: which does what?

Neem khali is the pest-management and slow-nitrogen input, while sarso khali is the faster nitrogen input and soil conditioner. If you are buying only one, pick sarso khali for vegetative growth and neem khali for soil where plants keep dying.

Mustard oil cake has about twice as much protein as neem seed cake, and protein is where the nitrogen sits. Feedipedia, produced by INRAE, CIRAD, AFZ and FAO, lists mechanically pressed mustard oil meal at 34.9% crude protein against 16.7% for neem seed cake. At the standard 6.25 factor, that is about 5.6% nitrogen against 2.7%. Mustard cake also carries more phosphorus, 11.1 g per kg against 5.4 g.

The importance of neem is not its nitrogen content. Azadirachtin, the main compound behind neem's performance against soil pests, sits in the seed at 3.92 mg per gram against 0.03 mg per gram in the leaves, roughly eighty times more.

Neem also slows the conversion of ammonium to nitrate, keeping nitrogen in the root zone instead of letting it drain away. The same trial recorded roughly a 60% reduction of nitrate leaching.

Will it burn roots, and does it smell?

Both cakes can burn roots when they accumulate round the stem or are heavily applied to a container of young plants. Oilseed cakes give off ammonia as they decompose. Maintain a distance of 5 cm from the stem, blend instead of pile, water in properly, and wait a week or two before sowing seed into freshly amended mix.

Sarso khali needs a little more care. When mustard cake gets wet, the enzyme myrosinase acts on the glucoside sinigrin and releases a volatile, very irritating oil. That is the reason mustard is pungent, and near germinating seed it is a real risk.

On smell, yes, for two to four days, strongest in the first 24 hours. Mixing it in and topping with dry soil or cocopeat handles most of it. The same step cuts fungus gnats, which breed in damp organic matter left exposed.

What neem khali and sarso khali will not do

Neither neem khali nor sarso khali is a complete fertiliser. Both are nitrogen-first amendments carrying little potassium, so flowering and fruiting plants still need a potassium source. Neem khali is not a knockdown spray, it works in the soil, not on leaves. And results arrive in weeks, not days.

For potassium, pair either cake with wood ash, or run a general plant growth promoter once plants are flowering and fruiting.

On pest control, neem khali acts on soil-dwelling organisms, not on aphids on a leaf. In one potted trial a defatted seed meal at 40 g per kg of soil cut root-knot nematode counts from 4,710 to 19 eggs and juveniles per mL of soil. That is one organism at a research rate, not a general pesticide.

On timing, nutrients release only as microbes break the cake down, so give it two to four weeks before judging anything. Across the rest of the terrace garden range, change one variable at a time.

Frequently asked questions

What is neem khali, and what is it called in English?

Neem khali is the solid cake left after oil is pressed from neem seed. In English it is called neem cake or neem seed cake. It is sold as a powder or as coarse granules and used as an organic soil amendment in pots, grow bags and beds, not as a foliar spray.

How is neem khali made?

Neem fruit is collected and dried, the seed is separated out, and the oil is pressed from it. The solid residue that remains is neem khali. Cold-pressed cake keeps more of the seed's residual oil and active compounds than solvent-extracted cake. Some products are milled from the whole dried seed rather than kernel residue alone.

Is mustard oil cake good fertiliser for plants?

Mustard oil cake is a good fertiliser for pots, mainly as a nitrogen source. Mechanically extracted mustard oil meal averages about 34.9% crude protein, roughly twice that of neem seed cake, which translates into a higher nitrogen content. It also supplies phosphorus and organic matter. It is low in potassium, so it works best alongside a potassium source.

Can neem khali be used for all plants?

Neem khali suits most vegetables, herbs, flowering plants and fruit trees grown in pots and beds. Use lower rates around seedlings and young transplants, since decomposing oil cake releases ammonia that can scorch fine roots. Keep the powder away from stems, mix it into the topsoil, and water thoroughly after applying.

How do you use neem khali powder in pots?

Use roughly 100 g of neem khali powder for a 10 to 12 inch pot, worked into the top 3 to 5 cm of soil. Keep it about 5 cm clear of the stem, then water thoroughly. Repeat every 30 to 45 days. Pots of 6 to 8 inches take 25 to 30 g.