This calendar’s monthly planting guidelines are based on USDA zone 9, but they are adaptable to most zones. To find your zone, go to the National Gardening Association’s website. If your zone is 7, 8, or 9, you can safely use this guide. If your zone is 4, 5, or 6, then add a month before beginning your spring tasks and start your fall tasks a month earlier. If your zone is 10 or 11, subtract a month to your spring tasks. Your fall and winter tasks should remain the same as the original guide if you are in zones 10 or 11. These are all general guidelines. Your specific microclimate, which depends on distance to a large body of water (like gigantic lakes or oceans) and elevation, will make your zone fluctuate. Consult your local county extension office to get more detailed zone and planting guide information.
Tasks for April:
- Seedling selection
- Hardening off
April and May are the prime months for planting out your tomatoes. Depending on where you live, May is a better planting month for those in Zones 1 through 7. But Zones 8 and above can usually plant in April. Always check your local extension office for specific information for your microclimate.
Many of you will be purchasing your tomato seedlings from nurseries or local pop-up sales. There are a few caveats to note when selecting plants. Of course, you should understand the difference in fruit size so you can grow as many pounds as possible. The different sizes of fruit dictate whether you can grow them in your specific garden space. A lot of it is sunlight availability and daily/nightly temperature swings. The larger the expected fruit size, the more sunlight the plant needs. Also, if you have a tough growing condition, stick to small- to medium-sized fruiters. You’ll get more bang for your buck that way. Check out the growing guide for December for more information on how to choose the best varieties for your garden.
Be sure to bring a jeweler’s loupe (a small pocket magnifying glass) of at least 20x when you go shopping for seedlings. Always inspect the leaves thoroughly on your selected plants to ensure you’re not bringing home pernicious pests that can thoroughly ruin your garden for years to come. Many of these pests are hard to see with the naked eye: thrips, russet mites, spider mites, psyllids. Google images of these pests to know what you’re looking for. Other pests that can easily be seen—and that are often seen on nursery plants—are aphids and whiteflies. In short, steer clear of anything that looks suspicious.
Another problem to avoid is purchasing a plant that’s too old. Yes, tomatoes can and do become stunted if left too long in their small containers. Clues that they are too “old” are: stiff, brittle leaves and stem, or the plant is starting to flower. Plants going into a reproductive stage via initial flowering means they’re getting too old for their pots and need either immediate potting up or planting out.
Tomatoes that are too old for their pot size do have an amazing ability to recover and grow. However, best practice dictates that the tomato should have been potted up before the hampering of its ability to grow as it wants. Use the good ol’ root-bound test by popping the pot off the bottom and seeing if the roots are circling around and around; however, the brittle leaf test and the flowering test are better indicators of advanced age in a seedling.
Another deal-breaker for you should be spotted or wilted leaves. This indicates the plant may be stressed and/or diseased. Wilting could be merely an indication of inadequate watering, but it can also spell trouble.
Whether you have purchase seedlings or have grown them yourself, they may need to be hardened off before planting. “Hardening off” means that the plant has been getting used to natural, full, direct sunlight, wind, and nighttime temperatures. If your seedlings have never spent a full day in all-day strong sunlight, or if they’ve not spent a night outdoors, it’s best to gently introduce them to these new stressors.
For sunlight: Don’t assume that purchased seedlings have been hardened off. Lots of seedlings are grown in semi-shaded greenhouses that then go directly into a sunny garden. This can cause a serious case of sunburn: necrotic, white patches on leaves due to intense sunlight. In some cases, it can kill a seedling. Even your own homegrown seedlings may need hardening off if they’ve spent all their time indoors.
Start putting your seedlings out in direct sunlight every day before your planting date. The process to get them used to all-day sun is—you guessed it—a bit at a time. If they haven’t spent any time outside, put them in the direct sunlight for two hours, then put them (still outside) in dappled sunlight. That could be under a shade cloth, lattice, or a bit of a shady tree (not full shade, though). Then, later that night, bring them inside again. Follow this procedure every day, gradually increasing the length of time they spend in full sun for four or five days. They are also acclimating to natural wind movement as well.
For temperature: Leave them out later and later in the evening before bringing them back inside at night. They need to start getting used to falling temperatures at night. You may need to put a timer on your phone to remind you to bring your babies in after dark. Do this for another few nights, extending the time bit by bit. When you do bring them in, put them in an unheated space, like a garage. When you are finally ready to plant, your seedlings, whether store-bought or grown yourself, will have acclimated to outdoor conditions sufficient to give them the best start possible.
Once you’ve checked your seedlings for bugs and age, and you’ve hardened them off properly, then it’s time to plant. Do one last check of your weather report. Delay planting if frost, cold rain, or heavy winds are forecasted; wait until those pass before planting out.
There are as many methods of planting as there are gardeners. However, the main elements of any good planting method are:
- Space plants apart properly
- Add amendments to the soil
- Plant them deep
- Initial watering
Tomatoes need space. Each plant should have at least two feet of space all the way around it; three feet is even better. Many people get excited about their fantasy tomato garden and want a huge amount of tomatoes. However, 20 squished-together plants will actually give you fewer tomatoes than eight properly spaced and cared-for tomatoes will. In this case, more is not always better.
Plan where you’ll be putting your tomatoes so they get maximum sunlight and good spacing both from each other and other plants. Two feet is a minimum. Of course, if you are growing dwarf varieties, then you can put them closer together.
Sometimes tomatoes are grown in highly controlled greenhouse environments where they’re spaced a foot apart. However, one of the many “controls” going on in those greenhouses is the tomatoes are pruned down to a single stem, which manages the plant growth. Also, these greenhouse plants are heavily leaf-pruned, allowing sunlight to reach the critical growing areas of the plant. And lastly, they are staked appropriately, often reaching heights of 20 feet. These conditions are for commercial greenhouse growers and difficult for home gardeners to emulate. Best to stick to what works.
If any of your tomatoes are determinate (short-statured plants), then make sure these are put on the south side of your indeterminate ones (tall tomatoes). If you don’t know which are which, do a Google search to inform yourself about the growing aspect of each of your tomatoes. If you plant your determinates intermixed with your indeterminates, the latter will quickly grow and start to shade your shorter, bush-like tomatoes. Once they are shaded, it’s very hard for them to produce fruit.
Another thing to be mindful of when planting out is the size of the tomato fruit for each of your cultivars. The bigger fruiters should have the maximum amount of sunlight. Again, the plants on the south side will shade those behind them. If you have determinants, those go on the extreme south. Then the largest beefsteaks go right behind those, then medium-sized fruiters behind those, and finally small fruiters behind everything else. That’s not to say that the small fruit-size plants want shade; it’s just that they tolerate the shadier locations better than beefsteaks do. And all indeterminates will get tall and start shading each other, so plan accordingly for the highest yield.
Planting hole amendments:
- Fish head or fish meal
- Bone meal
- All-purpose dry fertilizer
- Worm castings
- Mycorrhizae fungi
In March, you amended your plant beds. That’s all fine and good, but tomatoes sometimes need even more “oomph” when you plant them. Tomatoes are heavy, greedy feeders and need proper, consistent nutrition. Get some food underneath them when planting. This means dig a big, deep hole, throw some fertilizers down there, add some more soil to the top of the hole, then plant your tomato.
Here’s how to do that in more detail: After you’ve added clear plastic to the top of your raised beds, then cut a large X in the plastic where you plan to place each tomato plant. Fold open the plastic flaps and dig a nice, deep hole to accommodate all your amendments; the exact depth depends on how tall the seedling is that you start with. It should end up being halfway below the soil. In other words, submerge both the root ball and the lower half of the stem inside the hole, to be covered with soil. Plan accordingly for the depth; an average is around two feet deep. This is particularly important if you plan on using fish heads. You can either buy a whole fish, cut off its head, and use that (you can save them up in your freezer over the course of a year, if need be), or try to get fish heads free from a good butcher, fishmonger, or even local restaurant. If you’re reticent to put the fish head in the hole or simply can’t get your mitts on any, you can use two handfuls of fish meal as a substitute.
The next thing that goes into the hole are a couple of aspirin tablets. The aspirin helps jump-start the plant’s immune system. Put three or four crushed egg shells into the hole as well. The eggs supply a nice calcium boost, which will help prevent blossom end rot, that nasty brown patch on the bottom of tomatoes that lack calcium (the fish head bones and bone meal also help with that).
Bone meal is the next to go into the hole. Put in a heaping handful of bone meal (about a half a cup). This is a nice organic phosphorus source, which is essential for blossom production. More blossoms equal more fruit. Bone meal also increases calcium availability for the tomato.
Throw two handfuls (or about a half a cup) of an all-purpose organic fertilizer that contains the essential macronutrients of nitrogen, phosphorus, and potassium into the hole as well. Consider getting a mixture of 4-6-3 of those nutrients. This means 4 percent nitrogen, 6 percent phosphorus, and 3 percent potassium. Any organic mixture that is close to these numbers and dry (not only dry in the box but also meant to be used dry rather than mixed with water) works. Also, put a handful of pure worm castings in the bottom of the hole.
All of the above should be two feet below the surface if you’re using a fish head. If not, then the hole should be at least deep enough to accommodate a few inches of added soil and then half of the tomato plant. Put an inch or two of soil on top of the amendments in the hole. Then check the depth of your planting hole. Put the seedling, still in its pot, into the hole. Half of it (only) should be sticking up above the outside soil surface. If it looks like it will be buried deeper than halfway, add some more soil to the hole. If it looks like more than half will remain uncovered, remove some of the soil from the bottom of the hole that you added earlier, when you covered the amendments.
Once your hole is the correct depth, ease the plant out of the pot, and placing it in the hole, sprinkle a third of a cup or more of mycorrhizae fungi on the root ball. Several manufacturers sell this product, which is a naturally occurring substance out there in the plant world. This fungus has a symbiotic relationship with plants: It attaches to the roots, growing as the root ball grows and protecting the plant from diseases such as Verticillium and Fusarium wilts. It also creates a spongy mass around the root ball, increasing the plant’s ability to uptake nutrients and hold on to water. Try to sprinkle the mycorrhizae fungi on a wet root ball. This just means watering your seedling before planting, which is generally good practice anyway. Sprinkle the dry fungi on the root ball right over the planting hole. Anything that doesn’t stick will fall into the hole, and you’ll then be placing the root ball directly onto any fallen fungi debris.
You’re now ready to add the remaining soil. Backfill GENTLY—only one quasi-firm push settles the soil around the plant. Do not manhandle the soil around the plant by stomping on it or pressing too hard. That’s not necessary and it expels all the air out of the soil. Believe it or not, the roots need oxygen down there just as much as they need nutrients and water. A temporary well is then made around the plant base to catch the first watering.
The first watering is the most critical. Do it multiple times. Water it once, twice, and three times at least. Wait a few minutes to allow the water to drain through. If you have a deep hole—likely way more than 12 inches deep—you will be amazed at how much water it will take to wet the root ball a foot or more under the ground. So don’t be stingy with the water the first day. Thereafter, you’ll back off from the watering. Hand-water the tomatoes immediately after planting, particularly if it’s a warm or sunny day. Don’t rely on drip irrigation for this first day, as it’s often not fast enough to satisfy the tomato seedlings for their initial watering.
Thereafter, you won’t be watering your tomatoes on a schedule. It’ll depend on rainfall, temperature, whether your tomatoes are being grown on plastic. The next time you water your tomatoes after their initial planting will be when the underground soil starts to dry out. You won’t know that unless you dig down around the stem and check for dryness. The rule is if it’s moist two or three inches below the surface, then the tomatoes do not need watering.
Your newly planted tomatoes will benefit greatly from being protected at night for their first couple of weeks. The easiest way to do that is by using large plastic nursery containers or plastic buckets or rectangle plastic bins. Even cardboard boxes will do (as long as it’s not raining).
Invert your protectors, whether cardboard box or plastic receptacle, over each plant at dusk. Make sure the receptacle is large enough not to squish the top of the plant. These must all be removed each morning before or as soon as the sun touches them. If you don’t remove them each morning, the sun will be too much for them inside their bin or box. And, of course, no photosynthesis is happening, and proper ventilation isn’t either. So the bins go on top of each plant at dusk and are removed each morning.
Do this for the first two weeks, and your plants will reward you with rapid, robust growth. Be mindful that the tomatoes are not growing so rapidly that they touch the interior ceiling of your bin. If so, get a bigger receptacle to put over them. If your tomatoes are getting too tall (more than a foot high) during this initial two-week babying procedure, you may need to pop a small cage over them, or at least push a short bamboo stick in the ground and tie the tomato to the stick. Still, see if you can invert something over them at night during their first two weeks, regardless of their growth rate. You’ll be amazed at how fast they grow.