Friday, 2 November 2012

Determinate and Indeterminate Vegetables

I write a fair bit about individual varieties of vegetables, but as I sit and plan next springs' garden it occurs to me that I should write a bit about some of the criteria I use to select the varieties I do. This is part of the series on seed-saving, but it's about seed selection on the macro scale: what seeds to you choose to grow in the first place? One of the things I need to know about a variety before I plant it is whether it is determinate or indeterminate.

What do determinate and indeterminate mean?:

Simply, whether the variety of vegetable will grow to a given size, produce all of its crop within a short period of time, then die down (determinate), or whether it will begin to produce slowly, continuing to grow as a plant and  to provide the edible part of the plant over a prolongued (indeterminate) period of time.

Usually, the vegetables that are described as determinate or indeterminate are the ones where the fruit is the edible part of the plant; tomatoes, peppers, peas and beans and perhaps cucumbers or melons being the vegetables where you are most likely to see the term used. However, it is also applicable to potatoes. They are generally described as short season, medium season, or long season rather than determinate or indeterminate. However, short season potatoes set a certain quantity of potatoes, then they die down. Long season potatoes will, if you continue to hill them up at a judicious rate, continue to form tubers until cut short by cold weather. Mid season potatoes will continue to set potatoes for a while, but die down naturally before long season varieties would. As so often is the case, determinate and indeterminate describe the more extreme ends of the phenomenon, but many varieties will fall somewhere in the middle.

So which should you grow?:

Well, I don't know! It depends on what you are looking for. Like most things in life, there are advantages and disadvantages to each growth strategy.

Determinate varieties:

One advantage of determinate varieties is that they are often the earliest producing plants. If you want early peas, you almost certainly need to grow a determinate variety such as Misty, or Strike. Carol Deppe, in her book The Resilient Gardener, points out that when gardens are stressed by unpredictable and fluctuating weather, or by an inability of the gardener to give them full their full attention, determinate varieties make a lot of sense. For instance, I can often get a batch of Envol potatoes in and out of the ground before the potato beetles even show up for the season. Determinate varieties are also generally more compact than indeterminate varieties, making them more suitable for container gardening and other gardens without a lot of available space. They are also good in gardens which lack shelter - the larger indeterminate varieties are much more likely to be damaged by wind and weather. Determinate varieties may also mean multiple crops from one space. For instance, we like to grow Bellestar tomatoes for their early determinate crop of canning tomatoes. (Although I find determinate fresh eating tomatoes just annoying.) We pull them out and put our fall-planted garlic in their spot. You can follow early peas with bush beans very easily in our 150 day season, say Dual, followed by Provider. Finally, determinates are practically the only varieties grown by commercial vegetable growers because they are the ones that are suited to mechanical harvesting, or harvesting by seasonal labour crews. If you are growing your vegetables to freeze or can, having your harvest come in within a short period of time is very helpful -  you can do it all in a few batches, rather than in dribs and drabs.

Of course, there are also disadvantages. If you don't want to freeze or can your vegetables, but to cut and come again over a long season, these are very annoying - one week you are awash in more vegetables than you can manage, and the next week they are gone. Furthermore, I have found that determinate varieties have less disease tolerance in general than indeterminate varieties. Of course, tolerance varies between different determinate varieties, but in general they can't evade molds, fungi or viruses (or even nibbling pests) by simply outgrowing them the way indeterminate varieties often can. There is also a definite relationship between the amount of foliage a plant produces and the flavour of the parts used as vegetables. For instance, many people believe - and I am certainly one of them - that pole beans and peas (almost always indeterminate) almost always have better flavour than bush peas and beans (almost always determinate).

Indeterminate varieties:

The advantages and disadvantages of indeterminate varieties are, of course, pretty much the reverse of the above.

You will wait longer for your indeterminate vegetables to start producing (usually), and that means more time for something to go wrong. You will generally need more space for indeterminate varieties, and they will usually need much more in the way of structural support than determinate varieties. You had better like them, because they will keep coming... and coming... The fact that they are indeterminate doesn't mean you don't have to pick peas and beans every day - you do!

Still, there are a number of indeterminate tomato varieties where I am happy to eat every one as they come available, at a very reasonable pace. Their flavour is superb, the product of time and the support of a strong plant. They ignore, if not shake off, the growth of some diseases while the Bellestars mentioned above, on the other hand, are almost certainly in a race to produce something before all their leaves die and fall off. (That dratted septoria spot!)They are often much easier to pick, assuming you have supported them properly, and are often cleaner and in better condition because they haven't been draggling on the ground.

So what do we grow?:

As we become more experienced gardeners, we find we are using a combination of indeterminate and determinate vegetables so that we can have the best of both possibilities. No reason to stick to just one or the other - it's all about what works in your garden.

If you find a determinate variety you really like, but you lament how quickly it is over, you can plant several batches, timed to give you a harvest over the period you want. At least, that's the theory and what is usually recommended by garden writers. It works with some things; other times, whatever it is just sits there, regardless of when planted, and then when they decide the conditions are ideal they all take off together.

That has certainly been my experience with lettuce, which is marginal for us at best anyway. Spinach, too. Radishes work reasonably well. Peas? It all depends on the weather although peas planted for the fall - in theory a great idea - always seem to get mildew and fail to get really enthusiastic about spitting out the peas. Somewhat counterintuitively, I think it is best to plant indeterminate peas for the fall - they may out grow the mildew, unlike shorter determinates, although they need to be able to start in a relatively low number of days. Snap peas such as Amish Snap and Sugar Magnolia, seem very amenable to staggered plantings. Beans have proven reasonably amenable to staggered plantings. I don't have any data on cucumbers or melons, or tomatoes either for that matter. Onions etc have such a long growing season in general, and around here tend to be sensitive to day length anyway, that they are not particularly flexible in their planting times. On the other hand, we put some Russet Burbank potatoes in very, very late this summer (beginning of August!!!) and they still produced a respectable, if diminished crop. (We kept them going as long as we could under a hoop-house.)

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