[shokkyy]

I'm trying to get away from buying the expensive packs of various feeds and go more towards using straights. I do have a good local garden centre that sells all that stuff by the kilo, and it works out way cheaper than buying the brand name packs.

One thing that does cost quite a lot each year is buying the liquid tomato feed. If you've got quite a few tomato, pepper, chile, aubergine, courgette and cucumber plants and they all need a potash feed, it takes no time to get through a bottle. So I'm thinking about just buying a few kilos of straight potash from my garden centre instead. The downside of buying loose is you don't get a packet with instructions on it, and not having used straight potash before I'm hoping somebody can help me with a couple of questions I have.

If I just sprinkle loose potash on the soil around the plant, do I need to be careful about not getting it on leaves? The chap at the garden centre told me I can dissolve the potash in water, to be used as a liquid feed. But what concentration should I use? Again, is it safe to use as a foliar feed? And should I feed once a week once fruit is showing, same as a tomato feed?

As an aside, is there any benefit in adding a bit of lime to the planting hole with these types of plants?

[mumofstig]

tomato feed isn't just potash though, so would you add a different fertiliser for the N & P parts missing from your straight potash?

Lime? I always dig in a little calcified seaweed to provide the lime plus trace elements

[shokkyy]

All my beds had a dressing of seaweed meal and rock dust last autumn, so they shouldn't be short on any trace elements. And I always use chicken manure pellets and BFB as general purpose fertilisers on all beds as well. So really the potash is just there to address the additional needs of the swelling fruit.

[solway cropper]

There are plenty of organic sources of potash: comfrey, wood ash and seaweed being the most popular. The problem with using straight chemical fertilizers is that it is very easy to overdose the plants, something almost impossible with organics.

I'm not an ecofreak but I'm pretty sure that with a healthy soil/compost you shouldn't really need chemical fertilizers.

[someoneorother]

Need, probably not. Benefit from? Almost certainly, at least to some degree.

[shokkyy]

There are plenty of organic sources of potash: comfrey, wood ash and seaweed being the most popular. The problem with using straight chemical fertilizers is that it is very easy to overdose the plants, something almost impossible with organics.

I'm not an ecofreak but I'm pretty sure that with a healthy soil/compost you shouldn't really need chemical fertilizers.

Well yes, and most of the fertilisers I use are organic. But Levingtons Tomorite is not organic, and that's what I would be substituting with the potash. Whether to use chemical or organic fertilisers really is a personal choice, not a question of how good or bad your soil is. I'm aware it's possible to overdose plants with any fertiliser, and that's why I was asking for advice on dosage

[Salmo]

Presumably you are talking about sulphate of potash. The analysis is 50% potash so you do not need much.

If you want to work something out, as a comparison growmore is 7% potash. The application rate of growmore for a crop like potatoes is 4 ounces per square yard. So you would need just over half an ounce of sulphate of potash to achieve the same.

Probably the potash requirement of tomatoes is similar. That amount is for the whole season so if you want to apply it every week the amout would be minute. Perhaps that is why most growers are willing to pay for balanced tomato feeds?

[shokkyy]

Thanks, Salmo. I'm not sure I understand that logic though. I wouldn't have thought spuds required a high potash feed since they're not grown for flowers or fruit, so why would they need the same amount of potash as something like tomatoes? Looking at the Tomorite label, it's 8% potash and you're supposed to give 20ml per two plants weekly, which I would assume equates to 20g in powder/granular form. So presumably a straight potash would feed 12 plants for the same amount - does that sound about right?

[Salmo]

Potato fertilizers are high in potash.

                                                                Nitrogen  Phosphate  Potash 

Tomorite                                                        4               2.8           6.6
Vitax organic potato fertilizer                        4                2.5           8

It could be that it would be cheaper to use potato fertilizer on tomatoes rather than looking at straights. Tomorite does have some magnesium but you can easily spray with epsom salts.

Potash is very difficult to provide organically. The pee element of cow manure and bonfire ash are two. What others are there?

[shokkyy]

I use Vitax spud fertiliser as well but I'd never looked at the constituents on the label. I guess a potato plant must grow spuds more like fruit than root. I have also used the Vitax Organic Tomato, Chilli & Pepper fertiliser, which is also in granular form and is 5:2:8. You have to wonder whether that little bit of difference in nitrogen and phosphate really warrants buying two products, don't you. For this, they say you should apply on planting and then reapply at monthly intervals.

They also sell a liquid tomato feed like Tomorite, which is 4:4:8 and not organic and has to be applied at weekly intervals. Is it really necessary to be using a monthly granular fertiliser as well as a weekly liquid feed or is this just marketing? It does seem like overkill. If the granular monthly application was sufficient without the weekly liquid feed, it would be a whole lot cheaper and easier.

It's about £3.95 for 1L of Vitax liquid tomato feed, about the same as Tomorite. That 1L bottle will do 132 plant feeds, which isn't a lot when you've got 54 tomato, aubergine, pepper and chilli plants, plus cucumbers, squash, courgette, melon on top of that. If I did a weekly liquid feed for all my fruiting plants as per their recommendations, it adds up to a tidy sum by the end of the season, as well as taking quite a lot of time and effort. The organic seaweed tomato feeds seem to be even more expensive.

It's not that I'm tied into the idea of using straights, inorganic or organic, or anything else. I'm just trying to find a better way of keeping my fruiting plants well fed without spending a small fortune and taking a lot of time and effort.

[mumofstig]

as well as taking quite a lot of time and effort.

You still have to water them whether it's got feed in or not, so it won't save time and effort will it 

[shokkyy]

In pots, yes, but not necessarily in beds, depending on weather and soil in that bed. And I wouldn't normally put a third to a half of a watering can for each plant, but you have to if you're following the manufacturer's instructions on the dosage rate, which is loadsa trips to the tap.

[solway cropper]

Need, probably not. Benefit from? Almost certainly, at least to some degree.

What would be the benefit?

If sufficient nutrients are present in the soil/compost adding more would make no difference. The plants take what they need and no more. Far too many people keep bunging stuff in their soil without ever considering what the soil might actually need. If you are concerned buy a soil test kit and see what nutrients are actually present.

[shokkyy]

If anyone's interested, I emailed Vitax and asked them if it was necessary to use a liquid high potash feed on fruiting crops as well as their organic slow release fertiliser and they said no, it isn't. Their organic tomato, chilli & pepper fertiliser is designed to release slowly over a 4 to 6 week period and therefore supplies all the potash needs of fruiting crops.

Glad I asked, that's going to save me an awful lot of time and money

[gremlin]

If you are concerned buy a soil test kit and see what nutrients are actually present.

I agree with that. I spent £10 on a commercial lab soil  test and found that I already have twice the amount of potash and three times the amount of phosphorous and magnesium that are needed for Market Gardens.   I have saved several tubs of Growmore as a result.